Synovial sarcoma of the larynx and hypopharynx.

Synovial sarcoma represents a mesenchymal malignancy of unknown histogenesis that most often occurs in the lower limbs of young adults. The head and neck region is a relatively rare location, in which the hypopharynx and larynx are, respectively, the most and least often affected anatomic sites. Histologically, synovial sarcomas are classified into monophasic and biphasic variants. Immunohistochemistry plays a major part in the differential diagnosis, enabling the demonstration of epithelial differentiation. Both monophasic and biphasic synovial sarcomas are characterized cytogenetically by the reciprocal translocation t(X;18)(p11.2;q11.2) between chromosomes X and 18. Two cases of synovial sarcoma arising in the larynx and in the hypopharynx and in which cytogenetic analysis detected a diagnostic t(X;18) chromosome aberration are reported here.