An Unusual Presentation of Clear Cell Sarcoma

Abstract

A 34-year-old left-handed British male was referred with a slightly painful "recurrent ganglion" over the dorsum of the right wrist of six months' duration. One month prior to presentation the patient noticed the appearance of another small lump over the dorsum of the right hand which was asymptomatic. The "ganglion" was curetted ten months prior to admission in an outside clinic under local anesthesia. There was no report of the original specimen being sent for pathology.The patient underwent exploration and excision of both masses under regional block with a double tourniquet (Biers block). The dorsal wrist mass was found to originate from the sheath of the extensor carpi radialis brevis and adhering to the extensor retinaculum and dorsal capsule of the wrist. The dorsal wrist synovium was intact. The small mass over the dorsum of the right hand was originating from the sheath of the extensor tendon of the ring finger. Both were excised completely. Pathologic FindingsThe material presented consisted of: (1) an irregular piece of white rubbery tissue measuring 1.0 × 0.5 × 0.3 cm, all blocked; (2) a globular mass of pale gray rubbery tissue measuring 3.0 × 2.0 × 1.2 cm with a small segment of tendon tissue. On cut surface the mass was adherent to the tendon and was composed of pale gray soft tissue with areas of hemorrhage. Microscopically, the tumor was composed of nests and fascicles of polygonal rounded or spindle-shaped cells (Figure 1). They presented vesicular nuclei with very prominent single central nucleolei. The cytoplasm was abundant and often clear. Mitoses were frequent, climaxing to 4 per 10 high-power field, with an occasional atypical figure (Figure 2). In a few scattered fields there were multinucleated giant cells. Mucin and alcian blue stains were negative. Periodic acid-Schiff (PAS) stain gave a faintly positive response. Silver impregnation demonstrated a loose network of reticulin fibers that surrounded the tumor cells individually and in small nests. Fontana and iron stains did not react with tumor cells. Inconspicuous iron deposits were noted in the interstitium. The absence of demonstrable melanin in sections stained by the Fontana technique does not rule out the diagnosis of clear cell sarcoma (CCS) of the tendon sheath because melanin is demonstrable in only 50% of the cases [1,2].This tumor is readily differentiated from synovial sarcoma because of the absence of biphasic cellular pattern and intracellular mucin formation. The presence of clear cells and the nesting of the tumor cells on silver impregnation speak against a fibrosarcoma. The differentiation of epithelioid malignant schwannoma or a spindlecell melanoma is more difficult. The absence of peripheral nerves within the vicinity and of any history of neurofibromatosis are arguments against the former. The total absence of skin involvement and the partial clear cell pattern speaks against spindle-cell melanoma [3].