Postgraduate Education Corner

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Alexander Massmann , MD ; Takashi Kunihara , MD ; Peter Fries , MD ;. Günther K. Schneider , MD, PhD ; Arno Bücker , MD ; and Hans-Joachim Schäfers , MD.
CHEST

Postgraduate Education Corner CHEST IMAGING AND PATHOLOGY FOR CLINICIANS

A 77-Year-Old Woman With Dyspnea and Cardiac Mass Alexander Massmann, MD; Takashi Kunihara, MD; Peter Fries, MD; Günther K. Schneider, MD, PhD; Arno Bücker, MD; and Hans-Joachim Schäfers, MD

CHEST 2012; 142(2):523–527

obese woman was referred for evalA 77-year-old uation of worsening dyspnea over the past few

months (New York Heart Association functional class II-III). She denied chest pain or fever and was not taking any medications. Physical examination revealed no heart murmur or other significant findings. The patient’s medical history included mild hypertension, hypercholesterolemia, and diabetes mellitus. There was no history of rheumatic heart disease or pulmonary embolism. A routine chest radiograph revealed a dense, lobulated calcified mass (Figs 1A, 1B). Transthoracic and transesophageal echocardiography findings were suspicious for an intracardiac tumor, showing a well-circumscribed, encapsulated hyperechoic mass (3 3 4 cm) involving the posterior aspect of the mitral annulus (Fig 2). Central hypoechoic areas present were suspicious for central necrosis. There was no pericardial effusion. The lesion was sessile and demonstrated no significant Doppler flow. Assessment of the mitral valve revealed significant stenosis without evidence of insufficiency (mean diastolic pressure, 13 mm Hg). The left ventricular ejection fraction was within normal limits (70%). Coronary angiography showed no evidence of coronary arterial disease but revealed a postcapillary pulmonary hypertension (mean pulmonary arterial pressure,

Manuscript received July 26, 2011; revision accepted February 2, 2012. Affiliations: From the Department of Diagnostic and Interventional Radiology (Drs Massmann, Fries, Schneider, and Bücker) and Department of Thoracic and Cardiovascular Surgery (Drs Kunihara and Schäfers), Saarland University Hospital, Homburg/Saar, Germany. Correspondence to: Alexander Massmann, MD, Department of Diagnostic and Interventional Radiology, Saarland University Hospital, Kirrberger Straße, 66421 Homburg/Saar, Germany; e-mail: [email protected] © 2012 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.11-1825 journal.publications.chestnet.org

Figure 1. A, Posterior-anterior radiograph of the thorax. B, Lateral radiograph of the thorax. These radiographs demonstrate a circumscribed, lobulated, calcified mass (asterisks) located between the left atrium and ventricle.

Figure 2. Transesophageal echocardiography depicts a lobulated, echogenic mass at the posterior mitral annulus (asterisks). LA 5 left atrium; LV 5 left ventricle; MV 5 mitral valve. (Image courtesy of Jörg Schmidt, MD, Department of Cardiology, Saarland University Hospital, Homburg/Saar, Germany.) CHEST / 142 / 2 / AUGUST 2012

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Figure 3. A-C, Retrospectively, ECG-gated contrast-enhanced cardiac CT scan with multiplanar reconstructions in four-chamber view (A), short-axis orientation (B), and two-chamber view (C) demonstrates dense mitral annular calcifications (asterisks). PA 5 pulmonary artery; RA 5 right atrium; RV 5 right ventricle. See Figure 2 legend for expansion of other abbreviations.

36 mm Hg; mean pulmonary capillary wedge pressure, 27 mm Hg). Precontrast and postcontrast CT scan with retrospective ECG-gating (Philips Brilliance 64; Philips Medical Systems) and reconstructions during end systole confirmed a circular periannular mass with extensive calcification (Fig 3). There was no significant enhancement associated with this mass. Steady-state free precession cine MRI (Siemens Magnetom Aera 1.5 T; Siemens AG) showed an immobile, lobulated, periannular mass with smooth contour and low signal intensity (Fig 4). On both T2- and precontrast T1-weighted sequences, the lesion was markedly hypointense, reflecting the extensive calcification. Dynamic first-pass perfusion and 15-min delayed postcontrast (gadolinium benzyloxypropionictetraacetate 0.1 mmol/kg body weight) T1-weighted images revealed no significant central or peripheral enhancement.

Because of the patient’s symptoms and the otherwise poor prognosis associated with mitral valve stenosis in combination with pulmonary artery hypertension, the patient was scheduled for mitral valve replacement. Upon left atriotomy, a nodular, exophytic mass was identified adherent to the posterior portion of the mitral valve. After excision (Fig 5A) and unroofing of an irregular cavity (Fig 5B), about 20 mL of white, toothpaste-like material (Fig 5C) was expressed. Atrioventricular continuity was restored with a bovine pericardial patch (Fig 5D) and replacement valve. Postoperative transesophageal echocardiography revealed complete obliteration of the cavity without evidence of mitral regurgitation. Further microbiologic and histopathologic examinations were performed on the exophytic mass and its contents, revealing acellular, amorphous material with scattered calcifications (Fig 6). There was no evidence of granulomatous

Figure 4. A-C, Cardiac MRI (steady-state free precession sequences) in four-chamber (A), short-axis (B), and two-chamber (C) views depict a low-signal-intensity, well-circumscribed mass (asterisks) located at the base of the posterior mitral valve annulus. RVOT 5 right ventricular outflow tract. See Figure 2 and 3 legends for expansion of other abbreviations. 524

Postgraduate Education Corner

Figure 5. A, Intraoperative photograph after left atriotomy shows a nodular bulging of the surface of the mitral valve and its annulus marked with a forceps and a clamp. B, Subsequent incision reveals an irregular cavity. C, The cavity was filled with an amorphous toothpaste-like material. D, A pericardial patch was used for sealing the cavity and mitral valve reconstruction.

Figure 6. Histopathology of the acquired toothpaste-like material reveals calcifications (black area). There was no evidence of neoplasm or infection. A, von Kossa stain, original magnification 3 2.5. B, von Kossa stain, original magnification 3 5. (Image courtesy of Juliane Pokorny, MD, Department of Pathology, Saarland University Hospital, Homburg/Saar, Germany).

disease, and no mycobacteria were seen on acid-fast stain. There was no evidence of a neoplastic process. What is the diagnosis?

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Diagnosis: Caseous calcification of the mitral annulus Discussion Clinical Discussion Caseous calcification of the mitral annulus (CCMA), also known as liquefaction necrosis, is a rare form of mitral annular calcification typically affecting the posterior annulus.1,2 The typical differential diagnosis for this imaging appearance includes malignant intracardiac masses or an abscess.3-5 Usually, this lesion is clinically insignificant; however, in some cases there are associated cardiac conduction abnormalities or valvular dysfunction.6,7 CCMA represents a rare variant of mitral ring calcification. The latter is a commonly encountered abnormality, with a prevalence among patients undergoing echocardiography of 10% compared with a prevalence of 0.6% patients with CCMA.3 The prevalence of CCMA in the general population is 0.07%.3 Mitral annular calcification results from chronic atherosclerosis and often is accompanied by mitral valvular sclerosis, typically involving the posterior leaflet and annulus. Such calcifications are associated with the same risk factors as atherosclerotic vascular and coronary artery disease. In recent studies, CCMA has been linked with an increased cardiovascular morbidity and cardiovascular mortality and has been shown to be a marker of increased cardiovascular risk in middle-aged patients with atrial fibrillation.7-10 Asymptomatic patients with CCMA can be managed conservatively; although, CCMA has been associated with cerebrovascular thromboembolic events.7 Distal emboli and concomitant mitral valve defects are surgical indications for removal of the cavity and valvular reconstruction. Unroofing of the cavity alone without excision is not recommended because this may lead to embolization of the associated debris. Typically, a noneverting annular suture technique is recommended because this avoids tension in the calcified annulus and facilitates cavity obliteration. Insertion of a bioprosthetic mitral valve positioned over the cavity allows for continued, potentially beneficial compression of the cavity.11

findings often are nonspecific.2,3,5 Especially, calcified liquefaction (milk of lime) results in varying echo characteristics. Cross-sectional imaging, including cardiac CT scan and MRI, essentially are required for further validation of intracardiac masses. On the one hand, CT scanning, preferably obtained with ECG gating, can clearly confirm the presence of calcification in indeterminate cardiac masses as in the present case of extensive CCMA.12-14 However, CT scanning may fail to differentiate CCMA from other calcified intracardiac masses (eg, myxoma) or older organized intracavitary thrombus. On the other hand, cardiac MRI with its excellent soft-tissue contrast is advantageous to evaluate an indeterminate soft-tissue mass and may differentiate thrombi, vegetations, and myocardial abscesses from neoplastic masses (eg, myxomas) or cardiac metastases. However, MRI has, in fact, a disadvantage in the characterization of calcified lesions. The calcifications of CCMA typically appear as areas of low signal intensity on both T1- and T2-weighted images without significant enhancement following administration of contrast. Susceptibility artifacts due to pigmented proteinaceous material can similarly lead to a low-signal-intensity appearance. Therefore, the aforementioned imaging characteristics in combination with central liquefaction may be misleading in the diagnosis of an encapsulated abscess with surrounding fibrotic tissue. MRI alone may miss the presence of calcifications in a lesion.14-18 In summary, all the applied imaging studies, including echocardiography, CT scanning, and MRI have their advantages and drawbacks. Only together do they sufficiently point to the diagnosis of CCMA. Pathologic Discussion The gross appearance of CCMA is characterized by an ovoid, focal mass containing caseous fluid, calcifications, and proteinaceous debris. The homogeneous liquefied center is typically surrounded by a peripheral rim of calcifications.5,15,19 Histopathologically, an acellular, amorphous material with scattered calcifications characterizes the pathognomonic, toothpastelike material of CCMA. Conclusion

Radiologic Discussion Plain film radiography of the chest often is the first routine imaging method for the evaluation of cardiopulmonary disease. The following imaging method of choice for further assessment of cardiac pathology is transthoracic and transesophageal echocardiography. In the case of CCMA, echocardiographic 526

CCMA should be considered in the differential diagnosis of intracardiac masses. The knowledge of its imaging appearance allows accurate differentiation from other mass-like cardiac lesions. Surgical intervention is recommended in patients with compromised mitral valve function or associated clinical symptoms. Postgraduate Education Corner

References 1. Adler Y, Fink N, Spector D, Wiser I, Sagie A. Mitral annulus calcification—a window to diffuse atherosclerosis of the vascular system. Atherosclerosis. 2001;155(1):1-8. 2. Harpaz D, Auerbach I, Vered Z, Motro M, Tobar A, Rosenblatt S. Caseous calcification of the mitral annulus: a neglected, unrecognized diagnosis. J Am Soc Echocardiogr. 2001;14(8):825-831. 3. Deluca G, Correale M, Ieva R, Del Salvatore B, Gramenzi S, Di Biase M. The incidence and clinical course of caseous calcification of the mitral annulus: a prospective echocardiographic study. J Am Soc Echocardiogr. 2008;21(7):828-833. 4. Stamou SC, Braverman AC, Kouchoukos NT. Caseous calcification of the anterior mitral valve annulus presenting as intracardiac mass. J Thorac Cardiovasc Surg. 2010;140(1):e9-e10. 5. Zuber M, Oechslin E, Jenni R. Echogenic structures in the left atrioventricular groove: diagnostic pitfalls. J Am Soc Echocardiogr. 1998;11(4):381-386. 6. Novaro GM, Griffin BP, Hammer DF. Caseous calcification of the mitral annulus: an underappreciated variant. Heart. 2004;90(4):388. 7. Potpara TS, Vasiljevic ZM, Vujisic-Tesic BD, et al. Mitral annular calcification predicts cardiovascular morbidity and mortality in middle-aged patients with atrial fibrillation: the Belgrade Atrial Fibrillation Study. Chest. 2011;140(4):902-910. 8. Fox CS, Vasan RS, Parise H, et al; Framingham Heart Study. Mitral annular calcification predicts cardiovascular morbidity and mortality: the Framingham Heart Study. Circulation. 2003; 107(11):1492-1496. 9. Kanjanauthai S, Nasir K, Katz R, et al. Relationships of mitral annular calcification to cardiovascular risk factors: the MultiEthnic Study of Atherosclerosis (MESA). Atherosclerosis. 2010; 213(2):558-562.

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10. Zhang Y, Safar ME, Iaria P, et al. Cardiac and arterial calcifications and all-cause mortality in the elderly: the PROTEGER Study. Atherosclerosis. 2010;213(2):622-626. 11. Davidson MJ, Cohn LH. Surgical treatment of caseous mitral valve annulus calcification. J Thorac Cardiovasc Surg. 2006; 131(3):738-739. 12. Biteker M, Duran NE, Ozkan M. Caseous calcification of the mitral annulus imaged with 64-slice multidetector CT. Echocardiography. 2009;26(6):744-745. 13. Foley PW, Hamaad A, El-Gendi H, Leyva F. Incidental cardiac findings on computed tomography imaging of the thorax. BMC Res Notes. 2010;3:326. 14. Vanovermeire OM, Duerinckx AJ, Duncan DA, Russell WG. Caseous calcification of the mitral annulus imaged with 64-slice multidetector CT and magnetic resonance imaging. Int J Cardiovasc Imaging. 2006;22(3-4):553-559. 15. Fujiwara T, Fujita T, Toda K, Kobayashi J. Multimodality imaging of caseous calcification of mitral annulus. Eur J Cardiothorac Surg. 2012;41(2):451. 16. Di Bella G, Masci PG, Ganame J, Dymarkowski S, Bogaert J. Images in cardiovascular medicine. Liquefaction necrosis of mitral annulus calcification: detection and characterization with cardiac magnetic resonance imaging. Circulation. 2008; 117(12):e292-e294. 17. Monti L, Renifilo E, Profili M, Balzarini L. Cardiovascular magnetic resonance features of caseous calcification of the mitral annulus. J Cardiovasc Magn Reson. 2008;10:25. 18. Di Bella G, Carerj S, Andò G, et al. Cardiac imaging in the evaluation of mitral annulus caseous calcification. Int J Cardiol. 2006;113(1):E30-E31. 19. Vizzardi E, D’Aloia A, Farina D, et al. Imaging of caseous calcification of the mitral annulus. J Heart Valve Dis. 2009; 18(6):726-727.

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