Tenosynovial giant cell tumour (TGCT) is a rare benign proliferative disorder of the synovium characterised by destructive invasion by synovial-like mononuclear cells. Two variants have been distinguished: a localized (TGCT-L) and a diffuse (TGCT-D) type. TGCT usually affects adults with a peak incidence in the fifth and sixth decades of life and is more often seen in women than in men. One of the most common soft tissue tumours of the hand (finger joints and tendon sheaths), it is exceedingly uncommon in the head or neck. Only three cases of TGCT-D have been described in the literature. This report presents a case of TGCT-D in the temporomandibular joint.
A 29-year-old man presented to the authors’ unit in November 2005 for a swelling that had arisen in the right pretragic region about 4 years earlier. The patient was referred after having sustained a sports injury, which after about 2 months had developed into a swelling that had subsequently grown in size. Physical examination revealed a swelling about 2 cm in diameter, rounded, with indistinct borders; the overlying skin was normal in colour and appearance ( Fig. 1 ). On palpation the mass was firm, fixed to the underlying planes, and slightly tender. Routine assessment of jaw function showed normal mouth opening, preservation of lateral motion and protrusion, slight pain in the right temporomandibular joint (TMJ), and no facial nerve deficit. A magnetic resonance imaging scan disclosed the presence of a circumscribed oval mass (about 1.5 cm × 3 cm) laterally adjacent to the region of the right mandibular condyle ( Fig. 2 ), which was consistent with a lesion originating from the TMJ.
The mass was excised through a right preauricular approach extending to the ipsilateral temporal region. Since the teratomatous mass was adjacent and firmly adherent to the joint capsule ( Fig. 3 ), it was excised from the lateral side of the TMJ capsule, the intra-articular disc was preserved and the capsule was sutured.
It was difficult to cleave the mass from the surrounding tissues (temporal muscle, zygomatic arch and upper pole of the parotid gland), and its medial pole extended downward into the external acoustic meatus. Hemostasis was established, the mass was enucleated, a drain was placed, and the wound closed with a layered suture. The defect was not covered by any type of flap. Hemostasis was established, the mass was enucleated, a drain was placed, and the wound closed with a layered suture. Definitive histopathology revealed a histiofibroblastic proliferation with mononuclear cells composed of ovoid or spindle-shaped histiocytic elements with pale weak eosinophil cytoplasm with small ovoid or polygonal nuclei containing finely scattered chromatin and larger round elements with abundant cytoplasm often containing hemosiderin granules. The cells were variously mixed with epithelioid elements with clear cytoplasm containing numerous vesicular nuclei (multinucleated giant cells). In addition, there were scattered inflammatory elements, prevalently lymphocytes and histiocytes with foamy cytoplasm. No necrosis was present. The mass displayed no true capsule and the cellular elements, though closely crowded, were included in a hyaline collagen matrix covered with a delicate vascular network. Immunohistochemical analysis detected positivity for CD68 PGM1 in some of the ‘histiocytoid’ mononuclear cells and in nearly all of the multinucleated giant cells. These features were consistent with a diagnosis of diffuse tenosynovial giant cell tumour ( Fig. 4 ). There was no clinical or radiological evidence of tumour recurrence during the 5-year follow-up period.