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disease: this included periapical periodontitis, marginal periodontitis, radicular cyst, septic socket and oro- antral fistula . Extruded endodontic sealer was found ...

Analysis of maxillary sinusitis using computed tomography K. Yoshiura, S. Ban, T. Hijiya, K. Yuasa, K. Miwa, E. Ariji, O. Tabata, K. Araki, T. Tanaka, K. Yonetsu, E. Nakayama, Y. Ariji, M. Simizu, N. FtQiwara and S. Kanda Department of Oral and Maxillofacial Radiology, Facult y of Dentistry, Kyushu Univers ity, Jap an

Received 30 April 1992, and in final form 8 October 1992 Odontogenic maxillary sinusitis can be defined as sinusitis induced by a dental lesion. We examined the CT findings of 68 patients with maxillary sinusitis in order to differentiate between inflammation of sinus origin and inflammation of dental origin. Maxillary sinusitis was classified into four types according to clinical symptoms, history and conventional radiographic findings: type 1, simple sinusitis; type 2, odontogenic sinusitis; type 3, mixed sinusitis; type 4, slight sinus abnormality with a dental lesion. The relationship between the type of maxillary sinusitis and CT findings was analysed. Type 1 sinusitis exhibited severe pathological changes in both mucosa and bone which often extended into the nasal cavity and other paranasal sinuses . Type 2 sinusitis exhibited localized pathology on the unilateral antral floor. Type 3 sinusitis exhibited severe pathology characteristic of type 1 combined with type 2 sinusitis. Type 4 sinusitis could be differentiated by the cr findings into type 1 or type 2 sinusitis. The classification of sinusitis in this manner has implications for treatment planning, and cr should therefore be performed when conventional radiography does not provide sufficient information. Keywords: Tomography, X -ray computed; maxillary sinusitis,' periapical periodontitis

Dentomaxillofac. Radiol. , 1993, Vol. 22, 86-92, May

Odontogenic maxillary sinusitis is a special form of paranasal sinusitis. The term is used in many situations where maxillary sinusitis and a dental lesion co-existl". Yarnasakf classified 'so-called odontogenic maxillary sinusitis' into four types: type 1, independent pathology of the maxillary sinus; type 2, dental lesion followed by maxillary sinusitis; type 3, maxillary sinusitis followed by dental disease; type 4, advanced pathology of both maxillary sinusitis and dental disease. Type 2 maxillary sinus itis is the true odontogenic maxillary sinusitis. Sinus inflammation usually resolves with appropriate treatment of the causative tooth", However, it is sometimes unclear if the sinus lesion is entirely due to the dental lesiorr'. Odontogenic maxillary sinusitis often progresses to advanced maxillary disease including bony involvement , and inflammation of other paranasal sinuses or the nasal cavity4 .7 . Dental treatment alone is no longer effective in these cases . The purpose of this study was to clarify the cr findings in odontogenic maxillary sinusitis in order to differentiate between inflammation of maxillary sinus origin and inflammation of dental origin .

Department of Otorhinolaryngology of the University Medical Hospital with suspected maxillary sinusitis between 1985 and 1991 were reviewed. The chief complaints were maxillary pain, rhinoblennorrhea or discomfort. They were examined by conventional radiographs (panoramic, Waters' and dental radiographs) and these were assessed for evidence of dental disease: this included periapical periodontitis, marginal periodontitis, radicular cyst, septic socket and oroantral fistula . Extruded endodontic sealer was found in two cases and included in periapical periodontitis on the basis of the radiographic appearances. The diagnosis of radicular cyst was based on the histological findings following surgical excision.

86

Dentomaxillofac. Radiol. , 1993, Vol. 22, May

Severe thicken i ng

type

type

type

the.c~0

'Y9,m"k

Sixty-eight consecutive patients (32 males and 36 females, mean age 46.0 years) who attended Kyushu University Dental Hospital or were referred by the

Floor predominant

Level of the inferior concha

Level of

Materials and methods

Slight thickening

";~~

Figure I Diagram showing the three types of mucosal thickening seen on axial cr

CT for maxillary sinusitis: K. Yoshiura et al. Maxillary sinusitis was classified into four types on the basis of the clinical history and conventional radiographic findings. Type 1 was simple sinusitis with no associated dental lesion. Type 2 was odontogenic sinusitis in which a dental cause could be identified. Type 3 was severe sinus inflammation in the presence of a dental lesion whose contribution to the initial disease process could not be identified. Type 4 was mild sinus inflammation in the presence of a dental lesion whose contribution to the disease process was uncertain. The patients then underwent CT scanning (Somatom

DR, Siemens, Erlangen, Germany). They had been prescribed antibiotics for several days prior to examination. Four millimetre contiguous axial scans were performed without contrast enhancement. Coronal scans were added in 26 cases. The scans were examined for the type of mucosal thickening, the presence of inflammation in the other paranasal sinuses and/or nasal cavity, thickening or sclerosis of the antral wall and decrease in overall sinus size8-lO. In order to evaluate the grade of the soft tissue lesion and effects of the dental lesion on the mucosa, mucosal thickening was divided into three groups (Figure 1):

Figure 2 A typical case of type 1 sinusitis. a, Waters' view. The right maxillary sinus is totally opacified with sclerosis of the surrounding antral walls. b, Axial cr scan at the level of the zygomatic arch. Right maxillary sinus exhibits severe mucosal thickening with sclerosis and thickening of the surrounding antral walls; overall sinus size is decreased and accompanied by depression of the anterior wall

Figure 3 A typical case of type 2 sinusitis. a, Panoramic radiograph. Excess root filling material is present in small clusters over the apices of the upper left first molar; the antral mucosa is thickened on the antral floor and posterior wall. b, Axial cr scan at the level of the inferior concha. There is gross thickening of the antral mucosa around the extruded root fiIling material. c, Axial cr scan at the level of the zygomatic arch. Mucosal thickening, though less, persists

Dentomaxillofac. Radial., 1993, Vol. 22, May 87

CT for maxillary sinusitis: K. Yoshiura et al. slight thickening type, floor predominant type , and severe thickening type . Mucosal thickening Rreater than 4 mm was considered to be pathological . The slight thickening type was characterized by a thin mucosal thickening of the entire internal antral wall, or slight mucosal thickening of a localized part of the sinus. In the floor predominant type, mucosal thickening was more severe in the sinus floor than in other parts of the sinus. The severe thickening type had marked mucosal thickening throughout the whole sinus and was sometimes associated with a fluid exudate. Bony involvement was assessed by the presence of thickening and/or sclerosis of the anterior, nasal and infratemporal walls, and the zygomatic recess, on both the cr and conventional radiographs. A decrease in sinus size was determined by comparison with the contralateral side. In one patient both sinuses were considered to be decreased by comparison with the average. The CT findings were analysed in relation to the type of maxillary sinusitis and a definitive diagnosis made. On the basis of this decision type 4 sinusitis was reclassified as either type 1 or type 2. Sinusitis with bilateral inflammation, bone thickening at the zygomatic recess and pansinusitis or rhinitis was included in type 1, while unilateral sinusitis exhibiting floor predominant type mucosal thickening without pansinusitis or rhinitis was considered type 2 sinusitis. Examples of

the conventional radiographic and CT findings for each of four types are shown in Figures 2-5. The effects of the dental treatment were evaluated in 20 patients.

Results Of the total of 68 patients included in this study, 20 had bilateral and 48 unilateral maxillary sinusitis, making a total of 88 sinuses for analysis. Distribution of the bilateral and unilateral cases among the four types of sinusitis, and mean age of the patients in each type is summarized in Table I. Type 2 maxillary sinusitis was most frequently unilateral and more often found in younger patients. There were significant differences (ttest , P < 0.05) in mean age between type 2 and types 1 and 3. Table II lists the dental lesions observed in each type. Periapical periodontitis was the most common dental lesion in types 2, 3 and 4. Oro-antral fistula was also common in type 2. Table III shows the types of mucosal thickening in each type of maxillary sinusitis. Severe thickening type was frequently observed in types 1 and 3. In type 3, six of ten sinuses which exhibited severe mucosal thickening also had expansion at the semilunar hiatus.

Figure 4 A typical case of type 3 sinusitis. a, Panoramic radiograph. There are retained roots of the upper left second premolar. The left maxillary sinus is cloudy with thickening of the posterior wall. b, Waters ' view. The left maxillary sinus is totally opaque . c, Axial cr scan at the level of the zygomatic arch. The left maxillary sinus is completely opaque and there is sclerosis and thickening of the surrounding antral walls. d, Axial cr scan at the level of the lens. Left ethmoid air cells are also opaque

88 Dentomaxillofac. Radiol., 1993, Vol. 22, May

CT for maxillary sinusitis: K. Yoshiura et al.

Figure 5 A typical case of type 4 sinusitis. a, Panoramic radiograph. There is moderate marginal periodontitis, associated with gross calculus, most marked on the maxillary molars. b, Waters' view. There is slight mucosal thickening on the right antral floor and lateral (infratemporal) wall. c, Axial cr scan at the level of the inferior concha. There is mucosal thickening on the right antral floor. d, Axial cr scan at the level of the zygomatic arch. There is only slight mucosal thickening in the right maxillary sinus. Pneumatization is good. This case should be reclassified as type 2 sinusitis

Table I

Table III Distribution of the type of mucosal thickening seen on in relation to type of maxillary sinusitis

Distribution of the four types of maxillary sinusitis

Abnormal sinuses (no.) Bilateral cases (no.) Unilateral cases (no.) Mean age (yr)

Type J Type 2

Type 3

Type 4

Total

27 9(2)* 11 51.9

11 5(3)* 4 49.4

17 7(4)1 7 47.6

88 20 48 46.0

33 4(1 )t 26 39.2

Parentheses: contralateral side indicated a different type. • One case exhibited type 2 and one case type 4. t One case exhibited type 1. ~Three cases exhibited type 4. 'Three cases exhibited type 3 and one case type 1.

Number Mucosal thickening Slight Floor predominant Severe (Expansion at semilunar hiatus)

cr

Type J

Type 2*

Type 3

Type 4*

27

33

11

17

o

(0) 7 (25.9) 4 (14.8) 25 (75.8) 16 (59.3) 7 (21.2) 4116

zn

o (0) 1 (9.1) 10 (90.9)

4 (23.5) 12 (70.6) 0)

o(

6/10)

Values in parentheses are per cent. ·10 one case in each group. the type of mucosal thickening could not be evaluated due to fluid exudate.

Table II Distribution of the types of dental lesions seen on panoramic and intraoral radiographs in relation to the type of maxillary sinusitis

Type J Type 2

Type 3

Type 4

Sinuses (no.)

27

11

Periapical periodontitis Marginal periodontitis Radicular cyst Extraction socket Oro-antral fistula Total no. of lesions

0 0 0 0 0 0

17 8 4 2 3

(0) (0) (0) (0) (0)

33 16*(48.5) 5 (15.2) 5 (15.2) 1 (3.0) 8 (24.2) 35

9 2 0 0 0 11

(81.8) (18.2) (0) (0) (0)

Total

88 (47.1) 33 (23.5) 11 (11.8) 7 (17.6) 4 o (0) 8 17 63

Values in parentheses are per cent. • Marginal periodontitis accompanied the periapical periodontitis in two cases.

Table IV Distribution of inflammation in other paranasal sinuses and nasal cavity seen on cr in relation to type of maxillary sinusitis

Type J

Type 2

Type 3

Number 27 33 11 Other paranasal sinuses Ipsilateral 16 (59.3) 7 (21.2) 7 (63.6) Contralateral 14 (51.9) 3 (9.1) 5 (45.5) Nasal cavity 13 (48.1) 7 (21.2) 6 (54.5)

Type 4 17 4 (23.5) 4 (23.5) 5 (29.4)

Values in parentheses are per cent.

Dentomaxillofac. Radiol., 1993, Vol. 22, May 89

CT for maxillary sinusitis: K. Yoshiura et al. Table V Distribution by region of bony changes (thickening or sclerosis) of the antral wall as seen on cr in relation to type of maxillary sinusitis

Number Anterior wall Nasal wall Infratemporal wall Zygomatic recess

Type J

Type 2

Type 3

Type 4

27 8 4 12 11

33 2 2 6 1

11 6 2 7 8

17

(29.6) (14.8) (44.4) (40.7)

(6.1) (6.1) (22.2) (3.0)

(54.5) (18.2) (63.6) (72.7)

3 1 5 4

(17.6) (5.9) (29.4) (23.5)

Values in parentheses are per cent.

Table VI Comparison of the detectability of thickening or sclerosis of different parts of the antral wall by conventional radiography compared with cr CT Conventional radiography Detectability (no.) (no.) (%)

Nasal wall 9 Infratemporal wall 30 Zygomatic recess 24

3 23

33.3 76.7 54.2

13

In contrast, the floor-predominant type of mucosal thickening was more common in types 2 and 4. .Table IV shows the frequency with which inflammation extended into the other paranasal sinuses and the nasal cavity in each type. In almost half the cases of type 1 and type 4 it was found in the contralateral sinuses and nasal cavity: in contrast, such extension was rare in type 2. Table V analyses the extent of bony changes in different parts of the antral wall by type. Thickening or sclerosis in the infratemporal wall and zygomatic recess was a frequent feature of type 1 and type 4. Seventyseven per cent of sinuses with infratemporal wall thickening was detected on panoramic or Waters' view radiographs, but only 54% of those with zygomatic recess changes (Table VI). A decrease in overall size was observed in those sinuses with severe thickening (Table VII). In addition, five of nine sinuses, with a decrease in size, also had a concavity of the anterior antral wall. On the basis of the CT findings the 17 cases of type 4 Table VII Distribution on cr of a decrease in overall sinus size and depression of the anterior wall in relation to type of maxillary sinusitis

Number Decrease in overall sinus size Depression of the anterior wall

Type J

Type 2

Type 3

Type 4

27

33

11

27

5 (18.5)

o (0)

3 (27.3)

1 (5.9)

4/5

0/0

1/3

011

Values in parentheses are per cent.

Table VIII The results of the follow-up study on the effects of the dental treatment on the different types of maxillary sinusitis

Type J Improved Unchanged Changed Worse Radical surgery

90

Type 2

Type 3

7 2

2

Type 4

4 2

I

I I

Dentomaxillofac. Radiol., 1993, Vol. 22, May

sinusitis could be divided into 13 type 1 and four type 2. Table VIII shows the results of the follow-up study of the effects of dental treatment. In type 2 maxillary sinusitis dental treatment alone was successful in seven of 12 cases as well as four of the seven type 4. Two of these were among those reclassified as type 2 sinusitis.

Discussion Mucosal abnormalities are often observed in the maxillary sinus as an incidental finding I2-14. However, little attention has been paid to the significance of mucosal thickening on the antral floor, in spite of the possible effects of dental lesions. Patients sometimes complain of discomfort in that area, but m~y no.t repo~t any more substantial symptoms. A working dlagn?sls of odontogenic maxillary sinusitis would be appropr!ate in these circumstances. Localized antral mucosal thickening due to dental infection is termed 'mucositis' by Worth and Stoneman'", However, antral mucositis would be entirely asymptomatic. Although odontogenic maxillary sinusitis is a relatively common inflammatory disease in dentistry and otorhinolaryngology, the condition encompasses a variety of pathological conditions5 •6:16. It. may b~ limited to the lower portion of the maxillary sinus, or It may spread to other paranasal sinuses or the nasal cavity, leading to pansinusitis or rhinitis. Bony abnormalities are often observed8.17.18. The main purpose of this study was to clarify the characteristic CT findings in odontogenic maxillary sinusitis so as to distinguish it from simple maxillary sinusitis (type 1 in this study). Type 1 maxillary sinusitis is ~ simple sinu.sitis wh.i~h is not accompanied by dental disease. In this co~dlhon, bilateral sinusitis is almost as common as umlateral. In addition, in half the cases it was associated with pansinusitis or rh~nitis. Muc?sal. th.ickening was relatively severe in this type, which mdl.cates the presence of active inflammation which readily spreads to the contralateral and other paranasal sinuses, and to the nasal cavity. Bony abnormalities were also frequent in type 1 sinusitis (44%). They were readily detected on the infratemporal wall on conventional radiographs, but sometimes missed in the zygomatic recess. Bone thickening has often been reported in chronic sinusitis8.17.18. Proops'? postulated that it might be th.e end stage of the condition 17. Silver et at. reported that It produced a decrease in overall sinus size", a feature we found in nine of our cases. Cable et al.? observed thickening and sclerosis of the posterior wall of the antrum on CT in 60% of patients after Caldwell-Luc surgery; the volume of the cavity was also reduced. They suggested that this bony thicke~in~ might b.e ~ue to periosteal reaction to mucosal stnppmg, A similar process would occur in the periost~um o~ t~e a?tral wall in chronic sinusitis due to persistent irritation from inflammatory mucosa. We agree with Pr?op~17 ~h.at bony thickening is the end stage of chronic smuslh~. Concavity of the anterior antral wall was also seen !n five sinuses. This is likely to accompany a decrease 10 overall sinus size, similar to the postoperative bone reaction following the Caldwell-Luc procedure!". The presence of bony abnormalities in chronic sinusitis is

CT for maxillary sinusitis: K. Yoshiura et al. therefore a significant feature in the evaluation of the type of pathology, and for this reason CT should be performed wherever such changes are detected in the infratemporal wall on conventional radiographs. Bone thickening is also observed in fungal infections of the maxillary sinus!9.2o. The differential diagnosis on CT from simple chronic sinusitis depends on the presence of a high- accompanied by a low-density area. Type 2 maxillary sinusitis is a genuine odontogenic sinusitis caused by a dental lesion. In this study, it was characterized by a floor-predominant type of mucosal thickening with inflammation usually restricted to the infected sinus. Bone thickening was generally found on the lower infratemporal wall. Patients were significantly' younger than in other types of maxillary sinusitis. Taken together, these findings imply that genuine odontogenic sinusitis is relatively localized to the teeth and should respond well to elimination of the dental cause. Although the number of cases is small, this view is supported by our follow-up study. As reported previously", periapical periodontitis was the main cause of odontogenic maxillary sinusitis. Type 3 sinusitis is a combination of type 1 and type 2 sinusitis. Although a dental lesion (especially periapical periodontitis) was present, the CT pattern was similar to type 1. Ten of 11 cases exhibited gross mucosal thickening and six cases had expansion at the semilunar hiatus. While this type of maxillary sinusitis could be initiated by the dental lesion, the severity of inflammation is so severe as to suggest a concurrent maxillary sinusitis. Even if it is caused by dental disease, it is not cured by its elimination. A combination of dental and otorhinolaryngological treatment is required. A small number of type 2 cases, with both severe mucosal and bone thickening, may be a transitional form of type 3 suggesting that genuine odontogenic sinusitis can progress to more advanced inflammation involving the whole antrum. We propose that the final classification of the type of sinusitis should be refined with information obtained from CT, namely, that severe maxillary sinusitis with pansinusitis definitely caused by a dental lesion should be classified as type 3 sinusitis. In a broad sense, type 4 maxillary sinusitis can also be considered odontogenic, since a dental lesion and sinusitis coexist. However, our analyses indicate that this type includes both types 1 and 2 maxillary sinusitis. Sinusitis with bilateral inflammation, bone thickening at the zygomatic recess and pansinusitis or rhinitis should be included in type 1, while unilateral sinusitis exhibiting floor-predominant type mucosal thickening without pansinusitis or rhinitis should be considered type 2. In type 4 sinusitis, CT provides useful information on the exact extent of the inflammation and type of mucosal thickening which cannot be obtained from plain radiographs. Reclassified type 1 sinusitis should be treated first by an otorhinolaryngologist, even if there is a dental lesion. Any asymptomatic mucositis arising from it can be treated subsequently. Reclassified type 2 sinusitis should be treated dentally. The follow-up study indicated that dental treatment was successful in two of the four reclassified type 2 patients. Further experience with more cases is needed to confirm our reclassification. It could be in the type 1 cases that the antral infection had affected the adjacent tooth, causing the dental lesion", and that this lesion had itself subsequently affected the antral mucosa.

Type 3

Figure 6 Relationship between the types of maxillary sinusitis and sinus pathology. Type 1 sinusitis (~) involves the whole maxillary antrum. It spreads readily to the other paranasal sinuses and the nasal cavity (arrows). Type 2 sinusitis (11111) is restricted to the lower portion of the sinus in the presence of a dental lesion. Type 3 sinusitis is a combination of type 1 and type 2 sinusitis

In conclusion, we have shown how odontogenic maxillary sinusitis (type 2) can be differentiated from simple sinusitis (type 1). In addition, type 3 sinusitis can be distinguished from type 2. By limiting the diagnosis of maxillary sinusitis to these three types only, it is then possible to evaluate the cause and pathological extent of the disease (Figure 6). The type of sinusitis can be determined by clinical course and symptoms, conventional radiographs and, if necessary, CT. The application of CT to the diagnosis of putative odontogenic maxillary sinusitis is recommended in the following two cases: (1) in type 4, to evaluate the exact extent of the inflammation and type of mucosal thickening; (2) in type 2 sinusitis with possible thickening of the zygomatic recess. In these two circumstances, cr could alter the management of a patient.

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CT for maxillary sinusitis: K. Yoshiura et al.

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Address: Dr Kazunori Yoshiura, Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812, Japan.