Minute synovial sarcomas of the hands and feet: a clinicopathologic study of 21 tumors less than 1 cm.

Synovial sarcoma, one of the most common types of soft tissue sarcomas, usually presents in the proximal or middle portions of the extremities, often as a large mass with an aggressive clinical behavior. Gland-forming biphasic and spindle cell fibrous monophasic tumors are the most common subtypes. In this study, we evaluated 21 minute synovial sarcomas, <1 cm in diameter, from the hands and feet. These tumors occurred in 14 females and 7 males with a median age of 29 years (range, 8-60 years). Clinically, all tumors were thought to be benign processes such as a ganglion cyst or glomus tumor, and on microscopic examination, they were also often initially misinterpreted as benign lesions such as nerve sheath or (myo) fibroblastic tumors. Histologically, 7 tumors were biphasic and 14 were monophasic spindle cell variants. Microscopic calcifications were present in 8 cases and were prominent in 3 tumors. All monophasic tumors tested had elements positive for EMA, and all but one had reactivity for a keratin cocktail. S-100 protein-positive neuroma-like neural proliferations were commonly present in the monophasic but not in biphasic tumors. SYT-SSX fusion transcripts were demonstrated in 5 cases studied by polymerase chain reaction assay. All tumors were enucleated, followed by local reexcision of the site, and often combined with postoperative radiation. Three patients had amputation of the involved digit or metatarsal. Four patients had local recurrences, 2 of which were successfully treated; 2 of these patients were lost to follow-up. Despite some variation in treatment, all 12 patients with complete follow-up were alive and well, 2 to 32.2 years after surgery (median, 14.7 years), including 2 patients who received neither amputation nor postoperative radiation. Minute synovial sarcomas of hands and feet are clinically favorable tumors if completely excised; there is some evidence to suggest that they may be managed more conservatively than larger tumors. These tumors should be recognized as part of the spectrum of synovial sarcomas.