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Thieme Medical Publishers, Inc. (the “Publisher”) will be pleased to publish your article (the “Work”) entitled Imaging of Cysts and Bursae about the Shoulder in the Seminars in Musculoskeletal Radiology, Volume 18, Number 4, 2014.

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Imaging of Cysts and Bursae about the Shoulder Seema Meraj, MD1

Jenny T. Bencardino, MD1

Lynne Steinbach, MD2

1 Department of Radiology, New York University School of Medicine,

New York, New York 2 Department of Radiology, UCSF Medical Center, San Francisco, California

Address for correspondence Jenny T. Bencardino, MD, NYU Hospital for Joint Diseases, Department of Radiology, 301 East 17th Street - Sixth Floor, New York, NY 10003 (e-mail: [email protected]).

Semin Musculoskelet Radiol 2014;18:436–447.

Abstract Keywords

► ► ► ► ► ►

bursa ganglion cyst shoulder imaging MRI cyst mimics

A variety of fluid and fluid-like containing structures can be seen on routine MR imaging of the shoulder including bursal effusions and cystic lesions often in association with rotator cuff tears and impingement. Given its high soft tissue contrast and multiplanar imaging capabilities, MR imaging is the modality of choice in quantifying size, confirming fluid composition, assessing anatomical relationship to the glenohumeral joint, and determining the presence/absence of accompanying intra-articular abnormalities in association with the bursal and juxta-articular cystic findings.

A variety of fluid and fluid-like containing structures can be seen on routine MR imaging of the shoulder, including bursal effusions and cystic lesions often in association with rotator cuff tears and impingement. In general, bursae are located between closely apposed tissues of dissimilar content, thereby decreasing friction—that is, between tendon and bone or between muscle and bone. The two major types of cysts are ganglion cysts and synovial cysts. Whereas synovial cysts are lined by synovial cells and may communicate with the glenohumeral joint, ganglion cysts are lined by connective tissue and rarely communicate with the joint. Based on the size and location of the cysts, their cause, clinical implication, and treatment options vary significantly. Given its high soft tissue contrast and multiplanar imaging capabilities, MR imaging is the modality of choice in quantifying size, confirming fluid composition, assessing anatomical relationship to the glenohumeral joint, and determining the presence or absence of accompanying intra-articular abnormalities in association with the bursal and juxta-articular cystic findings. This article illustrates the MR appearance of the bursae and cysts about the shoulder and reviews their clinical significance.

Bursae and Synovial Recesses Subacromial-Subdeltoid Bursa The subacromial-subdeltoid bursa is the largest bursa in the body. It is composed of two bursae, the subacromial and the

Issue Theme Advanced Shoulder Imaging; Guest Editor, Jenny T. Bencardino, MD

subdeltoid, which communicate via a band of connective tissue in 95% of people.1 With the shoulder in the neutral position, the subacromial-subdeltoid bursa is bordered superiorly by the deltoid muscle and undersurface of the acromion, anteriorly by the biceps tendon groove, inferomedially by the supraspinatus tendon at its insertion, humeral neck, and the coracoid and part of the supraspinatus fossa, and inferiorly by the muscles and tendons of the rotator cuff2 (►Fig. 1). The subacromial-subdeltoid bursa therefore is separated from the glenohumeral joint by the rotator cuff and serves as a gliding interface between the inferior surface of the deltoid and the rotator cuff as well as the rotator cuff and the coracoacromial arch. Normally, this bursa contains a minimal amount of serous fluid, with the two opposing sides of the bursa separated by no more than 2 mm on MR imaging.3 The inner layers of the bursa are lined by synovium and the outer layers are lined by peribursal fat. Although focal obliteration of the peribursal fat plane has been found in normal, asymptomatic individuals, diffuse obliteration has been shown to be a sensitive indicator of rotator cuff pathology.4,5 Impingement of the subacromial space can result from congenital narrowing in the setting of abnormal acromial shape/orientation and chronic rotator cuff tendinosis and tearing, leading to superior migration of the humeral head and secondary subacromial-subdeltoid bursitis. Acute bursitis presents as a bursal effusion, with small amounts of fluid displacing the peribursal fat plane laterally,

Copyright © 2014 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) 584-4662.

DOI http://dx.doi.org/ 10.1055/s-0034-1384832. ISSN 1089-7860.

Cysts and Bursae about the Shoulder

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Fig. 1 Sagittal oblique graphic depicting the shoulder bursae. Asterisk identifies the subscapularis recess, the triangle identifies the subcoracoid bursa, and the pin identifies the subacromial-subdeltoid bursa Q1.

and larger effusions displacing the inferior margin of the peribursal fat plane lateral to the humeral shaft, resulting in a teardrop configuration.6,7 Patients with acute subacromialsubdeltoid bursitis clinically present with pain and limited range of motion, particularly with abduction and overhead activities, in the absence of history of antecedent trauma. In contrast, chronic subacromial-subdeltoid bursitis presents with a more dull pain and tenderness at the greater tuberosity. Fluid within the subacromial-subdeltoid bursa is a more specific finding of rotator cuff pathology on MR imaging including partial- and full-thickness rotator cuff tears, instability, and subacromial impingement. In the setting of fullthickness rotator cuff tears, fluid from the glenohumeral joint escapes into the subacromial-subdeltoid bursa via the defect (►Fig. 2). Bursal fluid that pools medial to the acromioclavicular joint and anterior to the humerus has a more specific association with rotator cuff tears.3 Complex fluid accumulations in the subacromial-subdeltoid bursa can be seen as a result of infectious (i.e., tuberculosis), inflammatory, and proliferative bursitis such as those associated with rheumatoid arthritis, crystal deposition disease (i.e., hydroxyapatite, calcium pyrophosphate, uric acid crystals), and synovial proliferative disorders (i.e., synovial chondromatosis, pigmented villonodular synovitis, and lipoma arborescens). Space-occupying solid material in the subacromial subdeltoid bursa may be a primary cause of subacromial impingement of the rotator cuff tendon.

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Fig. 2 Subacromial subdeltoid bursa. Coronal oblique T2 fat-suppressed image demonstrating the lateral to medial extension of fluid in the subacromial-subdeltoid bursa (white arrows) under the deltoid muscle and acromion, respectively, in the setting of rotator cuff tear (arrowhead).

and the glenohumeral joint do not normally communicate, and it typically contains little or no fluid. The bursa serves as a gliding interface between the subscapularis and the coracobrachialis and short head of the biceps tendon during rotation of the humeral head. Subcoracoid bursitis is a rare entity, characterized by anterior shoulder pain inferior to the coracoid process. However, prior studies have demonstrated that a natural communication exists between the subcoracoid bursa and the subacromial-subdeltoid bursa in anywhere from 10.7 to 55% of patients.3,8–10 As a result, fluid can be seen filling the subcoracoid bursa in the setting of distention of the subacromial-subdeltoid bursa from rotator cuff tears. Contrast material migrating within the subacromial bursa following subcoracoid injections can also consequently be misdiagnosed as a rotator cuff tear if one is not aware of this normal communication.9 Narrowing of the space between the coracoid process and lesser tuberosity (coracohumeral interval) most commonly occurs in individuals who participate in flexion/internal rotation activities, such as swimming and gymnastics, and results in impingement of the subscapularis tendon and superior and middle glenohumeral ligaments. The normal coracohumeral interval measures between 8.4 and 11.0 mm, with stenosis of this distance defined as < 6 mm, although subcoracoid impingement is primarily a clinical diagnosis11–14 (►Fig. 3). Subcoracoid bursal effusions and tears of the anterior rotator cuff and rotator interval was reported in association with narrowing of the coracohumeral interval.10

Subcoracoid Bursa The subcoracoid bursa is located inferior to the coracoid process, between the anterior aspect of the subscapularis tendon and the conjoined tendon of the coracobrachialis and the short head of the biceps (►Fig. 1). The subcoracoid bursa

Subscapular Recess The subscapular recess is an extension of the glenohumeral joint located between the anterior surface of the scapula and the subscapularis muscle, bordered superiorly by the superior Seminars in Musculoskeletal Radiology

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Fig. 3 Subcoracoid bursitis. (a) Axial proton-density fat-suppressed and (b) sagittal oblique T2 fat-suppressed images in the same patient demonstrating isolated fluid distension of the subcoracoid bursa (arrowhead) and narrowed coracohumeral interval (arrows) correlating with patient’s anterior shoulder pain.

glenohumeral ligament and inferiorly by the inferior glenohumeral ligament (►Fig. 1). The subscapular recess has been likened to a saddlebag when it hangs over the superior margin of the subscapularis tendon and becomes adherent to the anterior surface of the tendon.15 It is often mistaken for the subcoracoid bursa because it can extend anterior to the subscapularis muscle and into the subcoracoid space. However, the subscapular recess is separate from and superior to the subcoracoid bursa. When a large amount of fluid is present within the subscapular recess and subcoracoid bursa, a fibrous septum can be seen separating the two9 (►Fig. 4). The size of the subscapular bursa is inversely proportional to the size of the middle glenohumeral ligament; when the ligament is more diminutive, the recess is larger and vice versa.16 Unlike the subcoracoid bursa, the subscapular recess does not communicate with the subacromial-subdeltoid bursa in normal/asymptomatic people (►Fig. 5). The subscapular

recess can communicate with the glenohumeral joint via the sublabral foramen. The axillary pouch and the biceps tendon sheath also communicate with the glenohumeral joint; therefore, fluid in the subscapular recess is often physiologic and not indicative of pathology. In fact, loose bodies may extrude through a sublabral foramen into the subscapular recess.17,18

Axillary Pouch The axillary pouch (also known as the axillary recess) of the glenohumeral joint is located between the anterior and posterior bands of the inferior glenohumeral ligament, and it extends from the inferior one-third of the humeral head to the inferior two-thirds of the anterior glenoid. The axillary pouch is the primary anterior stabilizer when the joint is placed in abduction and external rotation.19 In the absence of joint distension, it is typically a small contracted structure. When distended with fluid, the axillary

Fig. 4 Subscapular recess and subcoracoid bursa. (a) Sagittal oblique T2-fat suppressed and (b) coronal oblique T2 fat-suppressed images demonstrating a hypointense septum (arrow) between a distended subcoracoid bursa (arrowhead) and subscapular recess (asterisk). Seminars in Musculoskeletal Radiology

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Fig. 5 Subacromial subdeltoid and subcoracoid bursae. Sagittal oblique T2 fat-suppressed image demonstrating fluid both in the subacromial-subdeltoid bursa (white arrow) and the subcoracoid bursa (black arrow) in a patient with a rotator cuff tear (not shown). Note, however, the lack of fluid within the subscapular recess (asterisk) because it does not communicate with the subcoracoid or subacromial-subdeltoid bursae.

pouch assumes a U shape on coronal oblique MR images (►Fig. 6). In the setting of humeral avulsion of the glenohumeral ligament or glenoid avulsion of the ligament, this U shape converts into a J shape, due to inferior displacement of the detached band of the inferior glenohumeral ligament20,21

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Fig. 7 Coronal oblique proton-density fat-suppressed image demonstrating a torn inferior glenohumeral ligament, resulting in a Jshaped configuration to the axillary pouch. Arrowhead identifies the glenoid insertion, asterisk the midportion, and arrow the humeral insertional fibers.

(►Fig. 7). On MR arthrography, contrast can be seen extravasating along the medial aspect of the humeral neck, in keeping with rupture of the inferior glenohumeral ligament. Changes in the axillary pouch on MRI have also been appreciated in the setting of adhesive capsulitis. Thickening of the axillary pouch > 4 mm is one of the defining characteristics of this process22 (►Fig. 8). In the early and subacute phases, the synovium can be hyperintense on T2 weighting and may enhance following intravenous contrast administration.23,24 Normal synovial plications in the axillary recess can be misconstrued as intra-articular debris when imaged in cross section if one is not aware of the presence of these structures.

Biceps Tendon Sheath

Fig. 6 Coronal oblique proton-density fat-suppressed image demonstrating an intact axillary pouch, with a U-shaped configuration. Arrowhead identifies the glenoid insertion, asterisk the midportion, and arrow the humeral insertional fibers.

At the proximal aspect of the intertubercular groove, the biceps tendon is surrounded by a synovial layer that is an extension of the synovial layer of the glenohumeral joint. Distally in the intertubercular groove, this synovial layer reflects back on itself, forming both a superficial and deep synovial layer, resulting in an intra-articular, extrasynovial structure.25 This blind pouch in the intertubercular groove is known as the biceps tendon sheath. A small amount of crescent-shaped fluid can normally be seen within the biceps tendon sheath, but it is considered an abnormal finding when a large amount of fluid distends the biceps tendon sheath in the absence of a glenohumeral joint effusion.26 Bicipital tenosynovitis is diagnosed on imaging when fluid is present within the biceps tendon sheath and/or the tendon itself is abnormal. Primary bicipital tenosynovitis is rare but can be seen in the setting of frictional tendinosis Seminars in Musculoskeletal Radiology

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Fig. 8 Adhesive capsulitis.(a) Coronal oblique T2 fat-suppressed image demonstrating marked axillary pouch thickening and edema (arrow). (b, c) Sagittal oblique T1 and T2 fat-suppressed images demonstrating effacement of the fat within the rotator cuff interval by intermediate and heterogeneous T2 signal related to reactive synovitis (asterisks).

secondary to biceps groove spurs (►Fig. 9). Distension of the sheath is more commonly seen in impingement and anterior rotator cuff tears as the glenohumeral joint communicates with this sheath.25 The intra-articular biceps tendon sheath may contain abnormal fluid and multiple low-signal bands representing synovitis in the setting of inflammatory synovial diseases, such as rheumatoid arthritis or adhesive capsulitis. Care should be taken not to misconstrue normal vessels in the bicipital groove as loose bodies in the tendon sheath. An empty distended tendon sheath can be seen when the intraarticular biceps tendon is torn and retracted27 (►Fig. 10). There may also be anomalies of the biceps tendon sheath itself including separation from the glenohumeral joint and duplication. The duplicated biceps tendon long head appears as a flattened tendon adjacent to the primary tendon within the

Fig. 9 Bicipital tenosynovitis. Axial proton-density fat-suppressed image demonstrating fluid distension of the biceps tendon sheath (arrow) in the absence of glenohumeral joint effusion (asterisk). Fluid outlines thickened internal septae indicative of chronicity. Seminars in Musculoskeletal Radiology

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bicipital groove, and it can be misinterpreted as a longitudinal split tear. A more rare entity is congenital absence of the long head of the biceps tendon within the bicipital groove. This condition has been shown to be in association with additional congenital anomalies (i.e., vertebral, anal, cardiac, tracheal, esophageal, renal, limb [VACTERL]) and on imaging demonstrates a smooth, shallow intertubercular groove.28

Periarticular Cysts Intramuscular Cyst Intramuscular cysts are an ancillary finding commonly seen in the setting of rotator cuff tear. These cysts may be unilocular or multilocular, and they are thought to arise as a result of fluid dissecting into the musculotendinous junction through a delaminating tear in the rotator cuff, with the long axis of the cyst paralleling the muscle fibers.29 Manval et al demonstrated that intramuscular cysts can be seen in equal proportions with full-thickness or partial-thickness rotator cuff tears.30 Because these cysts are typically small and located within the muscle, they are not seen during surgery or arthroscopy, and are not palpable on physical examination. The cysts may occur within the muscle of the torn tendon (►Fig. 11) but have also been shown to propagate from a torn tendon into an adjacent (different) rotator cuff muscle (i.e., from the supraspinatus tendon into the infraspinatus muscle31 (►Fig. 12). The latter finding may reflect the shared insertion of the supraspinatus and infraspinatus tendons onto the anterior facet of the greater tuberosity of the humerus.32,33 On MR imaging, intramuscular cysts typically demonstrate T2 and short tau inversion recovery hyperintense signal, with peripheral thin rim enhancement following intravenous gadolinium administration. The differential diagnosis includes residual intramuscular posttraumatic cysts in the setting of a remote muscle strain/contusion/tear.

Intratendinous Ganglion Intratendinous ganglion cysts of the shoulder are a very rare entity, with only two reported cases of intratendinous


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Fig. 10 Empty biceps sign. (a) AxialQ2 T2 fat-suppressed image with nonvisualization of the biceps tendon within the bicipital tendon sheath and groove. (B) Coronal oblique T2 fat-suppressed image in the same patient demonstrates fluid outlining a thickened and frayed long head biceps tendon stump (asterisk), with retraction to the level of the proximal humeral metaphysis.

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Fig. 11 Intramuscular subscapularis cyst. (a, b) Sagittal oblique T2 fat-suppressed images demonstrating an intramuscular subscapularis cyst (asterisk) in a patient with a subscapularis tendon tear near its insertion (white arrow). (c) Axial proton-density fat-suppressed image shows intratendinous delamination (black arrows) with fluid tracking from the tendon defect to the cyst.

Fig. 12 Intramuscular infraspinatus cyst. (a) Coronal oblique T2 fat-suppressed image demonstrating a high-grade footprint tear of the supraspinatus tendon (arrowhead) associated with (b) a small intramuscular cyst within the infraspinatus (arrow) on a sagittal oblique T2 fat-suppressed image. Seminars in Musculoskeletal Radiology

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Fig. 13 Spinoglenoid notch paralabral cyst. (a) Coronal T2 fat-suppressed and (b) sagittal oblique T2 fa- suppressed images of a patient with a posterosuperior labral tear (not shown) and a large paralabral cyst occupying the spinoglenoid notch (arrows), effacing the suprascapular neurovascular bundle. (c) Sagittal oblique proton-density image in the same patient demonstrates diffuse edema-like denervation change as well as fatty infiltration and atrophy of the infraspinatus muscle (asterisks).

ganglion cysts arising from the long head of the biceps tendon.34,35 The origin of these cysts is not well understood; however, they are believed to be related to acute36 or recurrent trauma37–39 such as rubbing or compression of the tendon against an osseous protuberance. Intratendinous ganglion cysts are commonly associated with tenosynovitis. Mucoid degeneration of the collagen fibers within the tendon and cellular hyperplasia associated with active secretion of mucin are thought to be the primary pathologic pathways that precede their development.39 On MR imaging, intratendinous cysts typically demonstrate low to intermediate signal on T1 and hyperintense signal on T2-weighted images. Intratendinous cysts are often lobulated and may extend into the muscle belly. Intraosseous erosion can also be seen. A stalk connecting the cyst to tendon sheath is the most reliable sign, as is seen with ganglion cysts elsewhere in the body. Postcontrast imaging may demonstrate thin peripheral enhancement of the fibrous wall.

Compression of the suprascapular nerve by a paralabral cyst as it passes through the suprascapular notch toward the supraspinatus fossa results in denervation of the supraspinatus and infraspinatus muscles. A paralabral cyst in the spinoglenoid notch, however, compresses the suprascapular nerve after its branch to the supraspinatus has taken off, resulting in isolated denervation of the infraspinatus muscle (►Fig. 13). In the subacute phase, denervation is characterized by diffuse muscle edema and hyperintense T2 signal.42 With chronic denervation, fatty infiltration of the muscle and/or atrophy develop, manifesting as hyperintense T1 signal (due to fat) and decrease in muscle size.

Paralabral Cyst Paralabral cysts are synovial cysts located in close approximation with a torn glenoid labrum. The mechanism of formation of these cysts is believed to be the result of a one-way valve that propagates fluid from the joint, through labrocapsular tears, and into adjacent pericapsular soft tissue.40,41 The MR appearance of paralabral cysts is quite variable, ranging from subcentimeter unilocular cysts to a large multiloculated, juxta-articular cystic lesion. The most common locations of paralabral cysts are posterior, associated with posterosuperior labral tears, and superior, associated with superior labral tears that extend anterior to posterior to the long head of biceps origin (superior labrum anterior and posterior [SLAP] tears). Small paralabral cysts are often asymptomatic and inconsequential. However, they may have clinical relevance depending on their location and increasing size. Paralabral cysts commonly extend extraarticularly, for example into the suprascapular or spinoglenoid notches in the setting of SLAP and posterosuperior labral tears, respectively. Seminars in Musculoskeletal Radiology

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Fig. 14 MRI geyser sign. Coronal oblique T2 fat-suppressed image demonstrating a chronic massive rotator cuff tear and high-riding humeral head articulating with the acromion and a large complex acromioclavicular joint cyst (asterisk). Note fluid communicating (arrow) from the glenohumeral joint via the acromioclavicular joint.


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allowing for communication between the glenohumeral joint and the acromioclavicular joint.43,44 Fluid then propagates from the glenohumeral joint, through the rotator cuff defect and the subacromial bursa, and into the acromioclavicular joint, resulting in the formation of a synovial cyst along the superior aspect of the acromioclavicular joint (►Fig. 14). With conventional arthrography, contrast material can be seen extending from the glenohumeral joint, through the acromioclavicular joint, and into the acromioclavicular joint cyst, a finding that has been referred to as the “geyser sign.”45 Fluid signal in the same regions on T2-weighted sequences on MR imaging has thus been referred to as the “MRI geyser sign.”46

Unstable Os Acromiale

Fig. 15 Unstable os acromiale. Axial T2 fat-suppressed image demonstrates fluid at the os acromiale synchondrosis (asterisk) with associated extensive subchondral cystic change within the articulating acromial process (arrows).

Paralabral cysts may also be seen in conjunction with inferior labral tears. Extra-articular extension of these cysts into the quadrilateral space can result in compression of the axillary nerve. As a result, the teres minor and/or deltoid muscles can demonstrate MR findings of denervation.

Acromioclavicular Joint Cyst (MRI Geyser Sign) Acromioclavicular joint cysts are rare but typically associated with full-thickness rotator cuff tears.43 With chronic fullthickness rotator cuff tearing, the humeral head subluxes superiorly, closely opposing the undersurface of the acromioclavicular joint, resulting in chronic friction. Over time, the inferior capsule of the acromioclavicular joint is disrupted,

An os acromiale is the result of failure of the acromial apophysis to fuse, most commonly between the meso-acromion and the meta-acromion.47 An unstable os acromiale may result when there is motion at the site of nonunion, resulting in the development of fluid at the unfused acromial ossification center (►Fig. 15). The presence of an unstable os acromiale predisposes patients to impingement syndromes because the un-united distal acromial apophysis is mobile and results in narrowing of the subacromial space due to inferior displacement on the deltoid muscle with shoulder abduction.48 Furthermore, increased mobility at the pseudoarthrosis results in degenerative changes, and degenerative cysts often develop.

Deltoid Dehiscence Open rotator cuff repairs require an incision through the deltoid muscle and detachment of the muscle fibers that insert onto the acromion to access the joint, which are then reattached prior to closing.49 Occasionally, the sutures may fail and fluid may develop within the surgical defect, thereby separating the deltoid muscle fibers. This feared postoperative complication is referred to as deltoid dehiscence (►Fig. 16). Primary deltoid dehiscence can alternatively be seen in the setting of deltoid tendon tears. MR imaging of

Fig. 16 Deltoid dehiscence. (a) Axial T2 fat-suppressed and (b) coronal T2 fat-suppressed images demonstrate a fluid-filled gap within the anterior deltoid (arrows) in the setting of deltoid dehiscence following rotator cuff tear repair (not shown). Seminars in Musculoskeletal Radiology

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Fig. 17 Cystic synovial sarcoma. (a) Coronal T1 and (b) coronal T2 fat-suppressed images demonstrate a mass within the deltoid muscle (asterisks) that follows isointense signal to muscle on T1 and heterogeneous to bright T2 signal. (c) Coronal T1 fat-suppressed postcontrast image shows irregular peripheral enhancement related to cystic synovial sarcoma confirmed on pathology.

individuals with deltoid dehiscence demonstrates fluid intensity signal extending between the deltoid muscle fibers and extending to the acromial attachment.

Intraneural Ganglion Intraneural ganglia are mucinous cysts that form within the epineurium of peripheral nerves. These cysts are a rare entity, particularly in the upper extremity, and are thus poorly understood; the vast majority has been demonstrated in the peroneal nerve. To our knowledge, only a handful of cases of suprascapular intraneural ganglia have been described in

the literature. A unifying articular (synovial) theory has been applied to peroneal intraneural ganglia, whereby fluid propagates from a degenerative synovial joint along an articular branch of the nerve and dissects into the epineurium of the parent nerve, where it forms an intraneural ganglion.50 Although prior literature on suprascapular intraneural ganglion has not found a communication between the glenohumeral joint and the suprascapular nerve on arthroscopy or MR imaging, the findings by Wang et al and Spinner et al separately also support the application of the unifying articular theory to upper extremity intraneural ganglia.51,52

Fig. 18 Axillary neuroma. (a) Coronal T1 and (b) Coronal T2 fat-suppressed images demonstrate a mass isointense to muscle on T1 and light bulb bright T2 signal within axillary space (asterisks), found to be a neuroma on pathology. Seminars in Musculoskeletal Radiology

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Fig. 19 Vascular malformation. (a) Coronal T1, (b) coronal T2 fat-suppressed, and (c) coronal T1 fat-suppressed postcontrast images demonstrate a heterogeneous T1 and T2 signal intensity intermuscular mass (asterisks) located between the trapezius and supraspinatus muscles, with a hypointense focus (arrow) consistent with vascular flow void. The mass heterogeneously enhances following intravenous contrast administration compatible with a vascular malformation.

Differential Diagnosis Synovial Sarcoma Synovial sarcomas are the fourth most common type of primary soft tissue sarcoma and most commonly seen adjacent to joints of adolescents and young adults 15 to 40 years of age.53 They are multilobulated heterogeneous masses of iso/ hyperintense T1 and predominantly hyperintense T2 signal on MR imaging (►Fig. 17). A sensitive but not specific “triple sign” has been described when there is mixed hyperintense, isointense, and hypointense signal reflective of hemorrhage or necrosis, solid cellular elements, and calcification or fibrosis, respectively, within the mass. A “bowl of grapes” appearance has also been described, reflecting areas of hemorrhage and cystic changes with intervening septations. Nonnecrotic solid areas demonstrate avid enhancement on postcontrast imaging.

on spin-echo images may be present within the mass that indicate thrombus or high-flowing vascular channels.56–58 Postcontrast imaging demonstrates avid enhancement, due to their vascular origin.

Hematoma A history of antecedent trauma in a patient with a new soft tissue mass is suggestive of hematoma. On MR imaging, blood products demonstrate varying T1 and T2 signal intensity based on the acuity of the hematoma with adjacent edema. Acute hematomas may present with hypo-isointense T1 and iso-hyperintense T2 signal due to the high concentration of intracellular deoxyhemoglobin59,60 (►Fig. 20). Over time, extracellular methemoglobin concentrations rise, resulting

Nerve Sheath Tumors and Other Tumors There are benign and malignant subtypes of nerve sheath tumors: schwannomas and neurofibromas, which are benign, and malignant peripheral nerve sheath tumors are malignant. On MR imaging, neurofibromas and schwannomas are typically fusiform/dumbbell shaped, and they demonstrate T1 signal hypointensity and T2 signal hyperintensity, with avid enhancement on postcontrast studies (►Fig. 18). Characteristically, these tumors demonstrate a “target sign,” reflecting peripheral high T2 signal and central low T2 signal due to the presence of fibrous tissue centrally and myxoid tissue peripherally.54 Malignant peripheral nerve sheath tumors tend to be larger than their benign counterparts (> 5 cm) and may demonstrate ill-defined margins.55

Varicosities and Vascular Malformations Varicose veins, hemangiomas, and vascular malformations adjacent to the shoulder may also be in the differential of periarticular cystic masses of the shoulder. On MR imaging, these masses are typically ill defined and demonstrate heterogeneous T1 and T2 signal (►Fig. 19). Serpentine flow voids

Fig. 20 Deltoid hematoma. Coronal T1 image demonstrates a large heterogeneous signal intensity mass in the deltoid muscle (asterisk) representing hematoma in a patient status post trauma, on Coumadin. Note is made of associated hemarthrosis (arrow). Seminars in Musculoskeletal Radiology

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in increasing T1 and T2 signal hyperintensity, and there is often subsequent development of a peripheral hypointense signal rim, reflecting hemosiderin deposition.61

Abscess

11 Gerber C, Terrier F, Zehnder R, Ganz R. The subcoracoid space. An

anatomic study. Clin Orthop Relat Res 1987;(215):132–138 12 Friedman RJ, Bonutti PM, Genez B. Cine magnetic resonance

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The differential diagnosis for a cystic mass in the shoulder also includes abscess. Clinically, patients may present with elevated white blood cell counts, elevated erythrocyte sedimentation rate/C-reactive protein, and fevers with a fluctuant mass. MR findings are nonspecific because abscesses are welldefined masses with a thick wall, central T2 signal hyperintensity, and adjacent edema.62 Classically, on postcontrast imaging soft tissue abscesses demonstrate peripheral ring enhancement.

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Cystic lesions are a common finding on MR imaging of the shoulder. These cysts may communicate directly with the adjacent glenohumeral or acromioclavicular joints, may arise from an adjacent bursa, or may arise from the soft tissues themselves. Knowledge of the anatomy of the bursae and other cystic lesions is important to avoid misdiagnosis because the causes and clinical implications of the cysts vary and may require resection or aspiration due to impairment in joint function and/or pain.

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References 1 van Holsbeeck M, Strouse PJ. Sonography of the shoulder: evalua-

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4

5

6

7

8

9 10

tion of the subacromial-subdeltoid bursa. AJR Am J Roentgenol 1993;160(3):561–564 Birnbaum K, Lierse W. Anatomy and function of the bursa subacromialis. Acta Anat (Basel) 1992;145(4):354–363 White EA, Schweitzer ME, Haims AH. Range of normal and abnormal subacromial/subdeltoid bursa fluid. J Comput Assist Tomogr 2006;30(2):316–320 Mitchell MJ, Causey G, Berthoty DP, Sartoris DJ, Resnick D. Peribursal fat plane of the shoulder: anatomic study and clinical experience. Radiology 1988;168(3):699–704 Zlatkin MB, Iannotti JP, Roberts MC, et al. Rotator cuff tears: diagnostic performance of MR imaging. Radiology 1989;172(1): 223–229 Hollister MS, Mack LA, Patten RM, Winter TC III, Matsen FA III, Veith RR. Association of sonographically detected subacromial/ subdeltoid bursal effusion and intraarticular fluid with rotator cuff tear. AJR Am J Roentgenol 1995;165(3):605–608 Vahlensieck M, Resendes M, Lang P, Genant H. Shoulder MRI: the subacromial/subdeltoid bursa fat stripe in healthy and pathologic conditions. Eur J Radiol 1992;14(3):223–227 Horowitz TM, Tocantins LM. An anatomical study of the role of the long thoracic nerve and the related scapular bursae in the pathogenesis of local paralysis of the serratus anterior muscle. Anat Rec 1938;71:375–386 Schraner AB, Major NM. MR imaging of the subcoracoid bursa. AJR Am J Roentgenol 1999;172(6):1567–1571 Grainger AJ, Tirman PF, Elliott JM, Kingzett-Taylor A, Steinbach LS, Genant HK. MR anatomy of the subcoracoid bursa and the association of subcoracoid effusion with tears of the anterior rotator cuff and the rotator interval. AJR Am J Roentgenol 2000;174(5): 1377–1380

Seminars in Musculoskeletal Radiology

Vol. 18

No. 4/2014

23

24

25

26

27

28

29

30

31

imaging of the subcoracoid region. Orthopedics 1998;21(5): 545–548 Lo IK, Burkhart SS. The interval slide in continuity: a method of mobilizing the anterosuperior rotator cuff without disrupting the tear margins. Arthroscopy 2004;20(4):435–441 Nové-Josserand L, Edwards TB, O’Connor DP, Walch G. The acromiohumeral and coracohumeral intervals are abnormal in rotator cuff tears with muscular fatty degeneration. Clin Orthop Relat Res 2005;(433):90–96 HorwitzQ3 MT, Tocantins LM. An anatomical study of the role of the long thoracic nerve and the related scapular bursa in the pathogenesis of local paralysis of the serratus anterior muscle. Anat Ret 1938;71:375–385 Petersilge CA, Witte DH, Sewell BO, Bosch E, Resnick D. Normal regional anatomy of the shoulder. Magn Reson Imaging Clin N Am 1993;1(1):1–18 Kaplan K, Sahajpal DT, Jazrawi L. Loose bodies in a sublabral recess: diagnosis and treatment. Bull Hosp Jt Dis 2006;63(3-4):161–165 Bencardino J, Fitzpatrick D, Shepard T, Hahn M, Jazrawi L. The sublabral foramen as a communicating pathway to the subscapularis recess. Skeletal Radiol 2011;40:485–515 O’Brien SJ, Neves MC, Arnoczky SP, et al. The anatomy and histology of the inferior glenohumeral ligament complex of the shoulder. Am J Sports Med 1990;18(5):449–456 Bui-Mansfield LT, Taylor DC, Uhorchak JM, Tenuta JJ. Humeral avulsions of the glenohumeral ligament: imaging features and a review of the literature. AJR Am J Roentgenol 2002;179(3): 649–655 Stoller DW. MR arthrography of the glenohumeral joint. Radiol Clin North Am 1997;35(1):97–116 Emig EW, Schweitzer ME, Karasick D, Lubowitz J. Adhesive capsulitis of the shoulder: MR diagnosis. AJR Am J Roentgenol 1995; 164(6):1457–1459 Carrillon Y, Noel E, Fantino O, Perrin-Fayolle O, Tran-Minh VA. Magnetic resonance imaging findings in idiopathic adhesive capsulitis of the shoulder. Rev Rhum Engl Ed 1999;66(4): 201–206 Tamai K, Yamato M. Abnormal synovium in the frozen shoulder: a preliminary report with dynamic magnetic resonance imaging. J Shoulder Elbow Surg 1997;6(6):534–543 Gückel C, Nidecker A. MR arthrographic findings in tenosynovitis of the long bicipital tendon of the shoulder. Skeletal Radiol 1998; 27(1):7–12 Needell SD, Zlatkin MB, Sher JS, Murphy BJ, Uribe JW. MR imaging of the rotator cuff: peritendinous and bone abnormalities in an asymptomatic population. AJR Am J Roentgenol 1996;166(4): 863–867 Kaplan PA, Bryans KC, Davick JP, Otte M, Stinson WW, Dussault RG. MR imaging of the normal shoulder: variants and pitfalls. Radiology 1992;184(2):519–524 Koplas MC, Winalski CS, Ulmer WH Jr, Recht M. Bilateral congenital absence of the long head of the biceps tendon. Skeletal Radiol 2009;38(7):715–719 Sanders TG, Tirman PF, Feller JF, Genant HK. Association of intramuscular cysts of the rotator cuff with tears of the rotator cuff: magnetic resonance imaging findings and clinical significance. Arthroscopy 2000;16(3):230–235 Manvar AM, Kamireddi A, Bhalani SM, Major NM. Clinical significance of intramuscular cysts in the rotator cuff and their relationship to full- and partial-thickness rotator cuff tears. AJR Am J Roentgenol 2009;192(3):719–724 Kassarjian A, Torriani M, Ouellette H, Palmer WE. Intramuscular rotator cuff cysts: association with tendon tears on MRI and arthroscopy. AJR Am J Roentgenol 2005;185(1):160–165

Q3


Meraj et al.

32 Clark JM, Harryman DT II. Tendons, ligaments, and capsule of the

48 Ouellette H, Thomas BJ, Kassarjian A, et al. Re-examining the

rotator cuff. Gross and microscopic anatomy. J Bone Joint Surg Am 1992;74(5):713–725 Mochizuki T, Sugaya H, Uomizu M, et al. Humeral insertion of the supraspinatus and infraspinatus. New anatomical findings regarding the footprint of the rotator cuff. J Bone Joint Surg Am 2008; 90(5):962–969 Kishimoto K, Akisue T, Fujimoto T, et al. Intra-tendinous ganglion in the long head of the biceps humeri. Skeletal Radiol 2008;37(3): 263–265 Rutten MJ, de Jong MD, van Loon T, Jager GJ. Intratendinous ganglion of the long head of the biceps tendon: US and MRI features (2010: 9b). Intratendinous ganglion. Eur Radiol 2010; 20(12):2997–3001 Robertson DE. Cystic degeneration of the peroneus brevis tendon. J Bone Joint Surg Br 1959;41-B(2):362–364 Thornburg LE. Ganglions of the hand and wrist. J Am Acad Orthop Surg 1999;7(4):231–238 Chen WS. Intratendinous ganglion and carpometacarpal boss. A report of two cases. Ital J Orthop Traumatol 1992;18(3):421–425 Kannus P, Józsa L. Histopathological changes preceding spontaneous rupture of a tendon. A controlled study of 891 patients. J Bone Joint Surg Am 1991;73(10):1507–1525 Tirman PF, Feller JF, Janzen DL, Peterfy CG, Bergman AG. Association of glenoid labral cysts with labral tears and glenohumeral instability: radiologic findings and clinical significance. Radiology 1994;190(3):653–658 Tung GA, Entzian D, Stern JB, Green A. MR imaging and MR arthrography of paraglenoid labral cysts. AJR Am J Roentgenol 2000;174(6):1707–1715 Robinson P, White LM, Lax M, Salonen D, Bell RS. Quadrilateral space syndrome caused by glenoid labral cyst. AJR Am J Roentgenol 2000;175(4):1103–1105 Craig EV. The acromioclavicular joint cyst. An unusual presentation of a rotator cuff tear. Clin Orthop Relat Res 1986;(202): 189–192 Tshering Vogel DW, Steinbach LS, Hertel R, Bernhard J, Stauffer E, Anderson SE. Acromioclavicular joint cyst: nine cases of a pseudotumor of the shoulder. Skeletal Radiol 2005;34(5):260–265 Craig EV. The geyser sign and torn rotator cuff: clinical significance and pathomechanics. Clin Orthop Relat Res 1984;(191):213–215 Cooper HJ, Milillo R, Klein DA, DiFelice GS. The MRI geyser sign: acromioclavicular joint cysts in the setting of a chronic rotator cuff tear. Am J Orthop 2011;40(6):E118–E121 McClure JG, Raney RB. Anomalies of the scapula. Clin Orthop Relat Res 1975;(110):22–31

association of os acromiale with supraspinatus and infraspinatus tears. Skeletal Radiol 2007;36(9):835–839 Q4 Deltoid dehiscence Spinner RJ, Atkinson JL, Tiel RL. Peroneal intraneural ganglia: the importance of the articular branch. A unifying theory. J Neurosurg 2003;99(2):330–343 Wang H, Terrill RQ, Tanaka S, Amrami KK, Spinner RJ. Adherence of intraneural ganglia of the upper extremity to the principles of the unifying articular (synovial) theory. Neurosurg Focus 2009;26(2): E10 Spinner RJ, Scheithauer BW, Amrami KK. The unifying articular (synovial) origin of intraneural ganglia: evolution-revelation-revolution. Neurosurgery 2009;65(4, Suppl):A115–A124 Murphey MD, Gibson MS, Jennings BT, Crespo-Rodríguez AM, Fanburg-Smith J, Gajewski DA. From the archives of the AFIP: Imaging of synovial sarcoma with radiologic-pathologic correlation. Radiographics 2006;26(5):1543–1565 Banks KP. The target sign: extremity. Radiology 2005;234(3): 899–900 Lin J, Martel W. Cross-sectional imaging of peripheral nerve sheath tumors: characteristic signs on CT, MR imaging, and sonography. AJR Am J Roentgenol 2001;176(1):75–82 Navarro OM, Laffan EE, Ngan BY. Pediatric soft-tissue tumors and pseudo-tumors: MR imaging features with pathologic correlation: part 1. Imaging approach, pseudotumors, vascular lesions, and adipocytic tumors. Radiographics 2009;29(3):887–906 Donnelly LF, Adams DM, Bisset GS III. Vascular malformations and hemangiomas: a practical approach in a multidisciplinary clinic. AJR Am J Roentgenol 2000;174(3):597–608 Vilanova JC, Barceló J, Smirniotopoulos JG, et al. Hemangioma from head to toe: MR imaging with pathologic correlation. Radiographics 2004;24(2):367–385 Speer KP, Lohnes J, Garrett WE Jr. Radiographic imaging of muscle strain injury. Am J Sports Med 1993;21(1):89–95; discussion 96 Slavotinek JP, Verrall GM, Fon GT. Hamstring injury in athletes: using MR imaging measurements to compare extent of muscle injury with amount of time lost from competition. AJR Am J Roentgenol 2002;179(6):1621–1628 O’Connor EE, Dixon LB, Peabody T, Stacy GS. MRI of cystic and softtissue masses of the shoulder joint. AJR Am J Roentgenol 2004; 183(1):39–47 Helms CA, Major NM, Anderson MW, Kaplan PA, Dussault R. Musculoskeletal MRI. 2nd ed. Philadelphia, PA: Saunders Elsevier; 2009

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Author Query Form (SMR/00799) Special Instructions: Author please write responses to queries directly on proofs and then return back. Q1: Au: Please define the abbreviations in the caption. They should be arranged alphabetically with a comma after the abbreviations and a semicolon between entries. Q2: Au: Please add mention of arrow to Fig. 10a caption. Q3: AU: Reference 15 appears to be a repeat of reference 8. And online sources are in disagreement about the journal title: Anat Ret or Anat Rec? Q4: AU: Please update this reference.