Calcifying/ossifying synovial sarcoma: a clinicopathologic and molecular study of 5 cases

Synovial sarcoma (SS) is a soft tissue sarcoma with a generally aggressive behavior. Calcifying/ossifying SS is a rare variant associated with a favorable prognosis.

The aim was to report clinicopathological features and molecular analysis of 5 cases of calcifying/ossifying SS.

Record of 370 cases of SS reported in the section of Histopathology, of a tertiary care Hospital, between 2002 and 2011 were retrieved. Five cases exhibiting extensive calcification and ossification were identified. Immunohistochemistry was performed using Flex technique. Molecular analysis of these 5 cases was performed later at the collaborative Hospital abroad, by reverse transcription polymerase chain reaction.

The ages of the patients ranged from 13 to 44 years (mean age 27 years; female to male ratio 1.6:1). The duration of symptoms ranged from 5 months to 5 years. Histologically, 4 were monophasic, and 1 was biphasic. Three cases exhibited extensive calcification and two extensive ossification. Immunohistochemical stain (epithelial membrane antigen was positive in all 5 cases, CKAE1/AE3 (3/4), Bcl2 (4/4), S100 (4/4), CK7 (2/2), CD99 (1/3) and vimentin (2/2). Intact RNA was obtained from 3 cases, all of which were positive for the SYT/SSX fusion transcript. Follow-up was available in 4 cases and ranged from 19 months to 85 months (mean 50 months). Local recurrence was seen in 2 cases. In conclusions, we report clinicopathologic features of 5 cases of calcifying/ossifying SS. The duration of symptoms and mean age of patients is similar to the literature. A slight female predominance was seen in contrast to a male predominance described in the literature. The clinical course of our cases validates the favorable prognosis of this rare type of SS.