Synovial ch Report of a case Anders Holmfund, DDS, P?zD,~ Firm Reinholt, MD, P!xD,~ and Hans Bergstedt, DDS, PhD,C Huddinge and Stockholm, Sweden KAROLINSKA

INSTITUTE

A case of synovial chondromatosis of the temporomandibular joint is reported in which initial clinical and radiographic data indicated disk derangement. Magnetic resonance imaging revealed distention and thickening of the lateral capsule but could not delineate the numerous loose bodies found at arthrotomy. The literature is reviewed, and diagnosis and surgical therapy are discussed.

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ynovial chondromatosis of the temporomandibular joint (TMJ) is a rare benign condition. Since the first modern report by Axhausen,’ about 40 caseshave been reported.2“1 Norman et a1.7have reviewed the reported cases. The pathogenesis is more an active metaplastic than a neoplastic process. According to Milgram,12 three phasesmay be recognized: active synovial diseasewithout loose bodies, synovial nodules with loose bodies, and multiple loose bodies with an inactive synovial disease. Clinical signs and symptoms are unilateral swelling over the joint area, pain in the joint area, and crepitus in the joint.7 Radiographic evidence of loose bodies may or may not be present.6s7 Recent reports indicate that computed tomographic scan and magnetic resonanceimaging (MRI) might be helpful for diagnosis.9slo We report a case of histologically verified synovial chondromatosis of the TMJ where both corrected sagittal tomography and MRI findings were negative. CASEREPORT

A Sl-year-old woman was referred to our clinic with complaints of swelling and pain in the region of the left aAssociate Professor, Department of Qral Surgery, Huddinge University Hospital, Huddinge. bAssociate Professor, Department of Pathology, Huddinge University Hospital, Huddinge. CAssociate Professor; Department of Radiology, Karolinska Hospital, Stockholm. 7/12/30561

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Fig. 1. Tl-weighted corona! magnetic resonance image of TMJ. Lateral capsule of left joint is distended and thickened.

TMJ. She first had clicking and pain in the left joint 4 years earlier. Stomatognathic treatment was performed for a period of 2 years, without alleviation of symptoms. Her medical history revealed migraine since the age of 10 years, for which she had been given propranolol hydrochloride as treatment. She had no history of systemic joint disease. Physical examination disclosed a swelling lateral to and slightly below the right TMJ that measured about 30 mm in diameter. The swelling was rather well defined, firm, and smooth, and was slightly tender to palpation. There was no erythema of the overlying skin. Auscultation with a stethoscope revealed crepitation. Salivary flow from the left parotid duct was normal. Results of routine laboratory tests were normal. Fine needle biopsy was negative showing only normal salivary gland tissue. Radiographic examination including corrected sagittal tomography showed a slight reduction in translation capacity of both left and right

Synovial chondromatosis of TMJ

Volume 73 Number 3

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2. Extirpated loose bodies of different shapes and

sizes.

joints. There wiereno signs of loose bodies or degenerative joint disease.MRI was performed on the left TMJ with a 1.0 T superconducting system (Magnetom, Siemens, Erlangen, Germany) with a head coil. Sagittal and coronal images were obtained in Tl- and T2-weighted sequences, and Tl-weighted sequenceswith intravenous contrast of gadolinium. The slice thickness was 4 mm at 4 mm intervals. The Tl-weighted image demonstrated a homogeneous soft tissue swelling lateral and anterior to the mandibular condyle with a signal slightly lower than that of muscle (Fig. 1). In Tl-weighted images with gadolinium the capsule gave a more intense signal, and in T2-weighted images the synovial fluid was prominent by the more intense signal of the entire lesion. The left joint was explored with the patient under general anesthesia. The joint was exposedfrom a lateral approach with a preauricular inverted L-shaped incision. The lateral capsule was distended and thickened. After incision of the capsule, synovial fluid and a few loose bodies immediately came out. Eighty-five loose bodies of variable size were collected from the superior compartment (Fig. 2). The inferior compartment was openedlaterally. No loosebodies or signs of synovitis were found. The fibrocartilage and the disk were unaffected, and no signs of degenerative joint diseasewere present. The lateral capsule and the lateral part of the anterior capsule were excised together with the affected synovial membrane. The unaffected disk was left in place, and the lateral disk attachment was sutured. The excised synovial tissue and a few loose bodies were sent the laboratory for histopathologic examination. Wound healing was uneventful, and normal mandibular function returned within 1 month. At 2-year follow-up there was no sign of recurrence and mandibular function was normal. HISTOLOGIC

FINDIINGS

Specimens were fixed in 4% phosphate-buffered formalin and embedded in paraffin according to a conventional protocol. Undecalcified sections were cut at 6 pm, stained with hematoxylin and eosin, and

Fig. 3. A, Synovium with unspecific chronic inflammation of low grade. Increased number of thin-walled vessels is seenin loose connective tissue. Cartilagenous areas were not observed.B, Loose bodies consisting of nodules of ordinary hyaline cartilage covered by fibrous connective tissue. Centrally in nodules hypertrophic chondrocytes are observed. (Hematoxylin-eosin stain; original magnifications: A, x75; B, x60.

subjected to light microscopy. The synovium showed slight to moderate inflammation of unspecific type with some areas of vascular proliferation. No nodular proliferation of metaplastic cartilage was observed (Fig. 3, A). The loose bodies (Fig. 3, B) consisted of common hyaline cartilage with central areas of chondrocyte hypertrophy and focal matrix mineralization, with no signs of ossification. At their surface the loose bodies were covered by fibrous connective tissue and a synovial membrane. DISCUSSION

Synovial chondromatosis of the TMJ is a rare condition. The clinical signs and symptoms often coincide with rheumatoid or degenerative joint diseases, and most signs and symptoms are thus unspecific.6, 7 Unilateral swelling of the joint region together with joint soreness and crepitus seem to be the most reliable signs and symptoms. 6,7 Radiographic features of

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March1992 synovial chondromatosis of the TMJ have been proposedby Noyek et al. l3 Most of these features, however, seemto be unspecific and are often found in degenerative joint disease and rheumatoid arthritis. Furthermore, in our case we found no signs of hard tissue disease on the tomograms. The detection of loosebodies also seemsdifficult with conventional radiography.6T7Computed tomographic scansand MRI may contribute to a correct diagnosis as indicated by some reports.9, lo In accordance with these reports, a rather well-defined mass was noticed predominantly in the lateral part of the joint and confined to the capsule and synovial membrane. No extension outside the capsule was found. The presence of intracapsular loose bodies, however, could not be demonstrated by tomography or MRI, probably because of their low mineral content. Arthroscopy provides direct visual inspection of the internal joint and thus may be of importance, as recently reported by McCain and de la Rua.* Affected synovium wasfound only in the lateral and anterolateral part of the superior compartment. The inferior compartment was not affected, and the disk and fibrocartilage of the superior and inferior compartments showed no signs of arthrosis despite a pronounced crepitation on joint auscultation. A total resection of the synovial membrane has beenadvocatedbecausethe remnants may be a source of recurrence.i4 Because the recurrence rate is low, surgical exploration with removal of the mass together with all loosebodies and the affected synovium seemsto be sufficient.6 In our case no recurrence occurred at 2 year follow-up. Malignant transformation of synovial chondromatosis of the TMJ has not yet been reported, and we found no histologic signs of multinucleation or pleomorphism. To summarize, clinical and radiographic features of TMJ synovial chondromatosis are not specific. MRI may indicate the disease particularly when thickening and distention of the lateral capsule is present. Arthroscopy is possibly the best method for

diagnosis of synovial chondromatosis. Treatment includes removal of the loose bodies together with the affected synovium. REFERENCES I. Axhausen G. Pathologie und Therapie des Kiefergelenkes.

Fortschr Zahnheilk 1933;9:171-86. 2. Ronald JB, Keller EE, Weiland LH. Synovial chondromatosis of the temporomandibular joint. J Oral Surg 1978;36:13-9. 3. Miller AS, Harwick RD, Daley DJ. Temporomandibular joint synovial chondromatosis. J Oral Surg 1978;36:467-8. 4. de Bont LGM, Blankestijn J, Panders AK, et al. Unilateral condylar hyperplasia combined with synovial chondromatosis of the temporomandibular joint. J Maxillofac Surg 1985; 13:32-6. 5. Jian XC, Liu SF, Yuang YH. Synovial chondromatosisof the temporomandibular joint. Int J Oral Maxillofac Surg 1988; 17:307-9. 6. von Arx DP, Simpson MT, Batman P. Synovial chondromatosis of the temporomandibular joint. Br J Oral Maxillofac Surg 1988;26:297-305. I. Norman JE, Stevenson ARL, Painter DM, et al. Synovial osteochondromatosisof the temporomandibular joint. J Craniomaxillofac Surg 1988;16:212-20. 8. McCain JP, de la Rua H. Arthroscopic observation and treatment of synovial chondromatosis of the temporomandibular joint. Int J Oral Maxillofac Surg 1989;18:233-6. 9. Dolan EA, Vogler JB, Angelillo JC. Synovial chondromatosis of the temporomandibular joint diagnosed by magnetic resonance imaging: report of a case. J Oral Maxillofac Surg 1989;47:41l-3. 10. van Ingen JM, de Man K, Bakri I. CT diagnosis of synovial chondromatosis of the temporomandibular joint. Br J Oral Maxillofac Surg 1990;28:164-7. Il. Forssell K, Happonen R-P, Forsell H. Synovial chondromatosis of the temporomandibular joint: report of a caseand review of the literature. Int J Oral Maxillofac Surg 1988;17:237-41. 12. Milgram JW. The classification of loose bodies in human joints. Clin Orthop 1977;124:282-91. 13. Noyek AM, Holgate RC, Fireman SM, et a!. The radiologic findings in synovial chondromatosisof the temporomandibular joint. J Otolaryngol 1977;6:45-8. l4. Ballard R, Weiland LH. Synovial chondromatosisof the temporomandibular joint. Cancer 1972;30:791-5.

Reprint requests:

A. Holmlund, DDS, PhD Department of Oral Surgery Karolinska Institute, Box 4064 S-141 04 Huddinge, Sweden