Synovial cyst of the temporomandibular joint: A case report and literature review

Abstract

Synovial cysts are lesions that usually occur on the wrist, foot and knee. They are rarely involved in the region of the temporomandibular joint (TMJ), with only 10 cases reported from 1978 to 2007. The authors report a case of a synovial cyst of the TMJ in a 45-year-old woman. The patient presented with a right preauricular swelling, 1 cm anterior to the tragus. A computed tomography (CT) scan showed a small oval hypodense mass of soft tissue in the right temporomandibular region with no relation to the condyle. Fine needle aspiration reported a synovial cyst of the TMJ. The patient was taken to the operating room and a preauricular approach extending to the temporal region was carried out resulting in surgical excision of the mass. The histological findings were consistent with the diagnosis of a synovial cyst. The long term clinical and radiological follow-up (after 18 months) showed no sign of recurrence. The authors suggest, in accordance with the literature, that a surgical approach should be the treatment of choice in the case of a synovial cyst of the TMJ.

Synovial cysts rarely occur in the region of the temporomandibular joint (TMJ) . They are usually present on the extensor surface of the wrist and to a lesser extent on the dorsal surface of the foot and lateral aspect of the knee . Only 10 synovial cysts in the region of the TMJ have been reported .

In the literature, the therapy most frequently suggested is surgical excision of the synovial cyst . A high success rate has been reported . The authors present a case of a synovial cyst of the TMJ treated successfully with a surgical approach.

Case report

A 45-year-old woman presented with a right preauricular swelling situated 1 cm anterior to the tragus ( Fig. 1 ). She reported that it had been growing slowly and had been present for approximately 1 year. Her medical history was unremarkable. She had no history of TMJ dysfunction and she denied any recent trauma to the ear or mandible. Her physical examination showed a soft, tender, non-erythematous swelling, 2 cm in size, in the right preauricular area lateral to the TMJ. It was fixed to the underlying structures and was painless.

Fig. 1
Right preauricular swelling at clinical examination.

The patient had normal mouth opening, without deviation, and the mandibular range of motion was normal in all directions. There was no sound and pain in the TMJ during mandibular motion in any direction. There was no facial nerve paralysis or paresis. The rest of the head and neck examination was unremarkable.

A fine needle aspiration was performed. The picture showed cytological amorphous proteinaceous material in which epithelial cells without atypia were observed compatible with a synovial origin. The results were compatible with a synovial cyst of the TMJ.

A sonogram of the area showed a hypoechoic cystic formation of about 13 mm × 8.5 mm × 10 mm, adjacent to the right TMJ. The parotid and submandibular glands were regular, without ectasia of the salivary ducts, with no evidence of lateral lymph node swellings. A computed tomography (CT) scan was obtained, which showed a small oval hypodense mass of soft tissue in the right temporomandibular region with no relation to the condyle ( Fig. 2 ).

Fig. 2
Coronal CT scan shows a right preauricular lesion not involving the parotid gland.

The patient was taken to the operating theatre and a preauricular approach extending to the temporal region was carried out to gain access to the right TMJ. The incision was made through the skin and subcutaneous tissues (including the temporoparietal fascia) as far as the temporal fascia (superficial layer). An incision of the superficial layer of the temporal fascia was performed and dissections were subsequently taken at the level of the zygomatic arch, as far as the lateral surface of the capsule of the TMJ. A 2 cm × 2 cm mass in and connected to the posterior lateral part of the joint capsule was found. The mass was isolated carefully from the lateral surface of the capsule, excised and sent for histological examination. The wound was sutured in layers and a pressure bandage was applied, which remained in place for 3 days.

The histological examination of the excised mass showed a cystic space lined by synovial cells with a cartilaginous nucleus for diagnosis of the site. The histological findings were consistent with the diagnosis of a synovial cyst ( Fig. 3 ).

Fig. 3
(a) Macroscopic image of cystic wall. The black arrow shows epithelial cells and the red arrow shows the cartilaginous nucleus for diagnosis of the site (E/E 400× magnification). (b) Positive immunohistochemistry for anti calretinin (400× magnification).

The follow-up examination at 18 months revealed no sign of recurrence following clinical and radiological investigations.

Discussion

A synovial cyst of the TMJ is rare with only 10 cases reported in the literature ( Table 1 ). There is a male to female predominance of approximately 7–2. Including the present case, the average age of the patients was 42.8 years (range 22–65 years). The aetiology is unknown . Synovial cysts seem to be caused by an increase in intra-articular pressure due to trauma or to an inflammatory process (rheumatoid arthritis, osteoarthritis or synovitis ), which causes a capsular herniation of the TMJ into the surrounding tissues. A displacement of synovial tissue during embryogenesis and an abnormal force on the joint resulting from a dysfunction of the TMJ have also been reported as possible causes .

Table 1
Reported cases of synovial cyst of the TMJ in the literature.
First author Published time (year) Cases Age (years) Gender (F/M) Treatment Follow-up (months) Recurrences
J aneca and Conley 1978 1 50 M Surgical Not stated Not stated
R eychler et al. 1983 1 30 F Surgical Not stated Not stated
F arole and J ohnson 1991 2 22 M Surgical 12 No
B onacci et al. 1996 1 46 M Arthroscopic 12 No
C hang et al. 1997 1 38 M Surgical 18 No
C hen et al. 1998 1 58 M Surgical Not stated Not stated
G oudot et al. 1999 1 65 M Surgical Not stated Not stated
L omeo et al. 2000 1 47 F Surgical 6 No
M oatemri et al. 2007 1 30 M Surgical 6 No
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Feb 5, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Synovial cyst of the temporomandibular joint: A case report and literature review
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