Synovial sarcoma with ossification and calcification with SS18 immunochemical expression and rearrangement by fluorescent in situ hybridization / Sarcoma sinovial con osificación y calcificación, con expresión de SS18 por inmunohistoquímica y reordenamiento de SS18 por hibridación in situ fluroescente

Synovial sarcoma is a soft tissue tumor of uncertain origin. Generally, it is a monophasic spindle cell neoplasm that can have glandular-like structures. Ossification and presence of calcification is a rare phenomenon with only a few reported cases. We present the case of a young male with a synovial sarcoma of the right foot. Histology revealed prominent deposits of tumoral osteoid and coarse calcifications. The diagnosis was confirmed by the expression of SS18 by immunohistochemistry and the demonstration of the rearrangement of the SS18 gene by fluorescent in situ hybridization. We reviewed the literature for synovial sarcoma with prominent ossification or calcification, and to the best of our knowledge, this is the first case with expression of SS18 by immunohistochemistry. The main differential diagnoses are osteosarcoma (both primary of bone and extraosseous) and sclerosing epithelioid fibrosarcoma.(AU)

El sarcoma sinovial (SS) es un tumor de partes blandas de origen incierto. Generalmente es una neoplasia monofásica de células fusiformes que puede tener estructuras de tipo glandular. La osificación y la presencia de calcificaciones es un fenómeno raro, con pocos casos reportados. A continuación presentamos el caso de un hombre joven con un sarcoma sinovial del pie derecho que en la histología mostró depósitos de osteoide tumoral y calcificaciones gruesas. El diagnóstico fue confirmado por la expresión de SS18 por inmunohistoquímica y la demostración del reordenamiento del gen SS18 por hibridación in situ fluorescente. Revisamos la literatura referente a sarcoma sinovial con osificación o calcificación prominente, y este es el primer caso con expresión de SS18 por inmunohistoquímica. Los principales diagnósticos diferenciales son con osteosarcoma (tanto primario de hueso como extraóseo) y fibrosarcoma epitelioide esclerosante (sclerosing epithelioid fibrosarcoma [SEF]).(AU)

Synovial sarcoma with ossification and calcification with SS18 immunochemical expression and rearrangement by fluorescent in situ hybridization.

Synovial sarcoma is a soft tissue tumor of uncertain origin. Generally, it is a monophasic spindle cell neoplasm that can have glandular-like structures. Ossification and presence of calcification is a rare phenomenon with only a few reported cases. We present the case of a young male with a synovial sarcoma of the right foot. Histology revealed prominent deposits of tumoral osteoid and coarse calcifications. The diagnosis was confirmed by the expression of SS18 by immunohistochemistry and the demonstration of the rearrangement of the SS18 gene by fluorescent in situ hybridization. We reviewed the literature for synovial sarcoma with prominent ossification or calcification, and to the best of our knowledge, this is the first case with expression of SS18 by immunohistochemistry. The main differential diagnoses are osteosarcoma (both primary of bone and extraosseous) and sclerosing epithelioid fibrosarcoma.