Endometriosis at the knee. A case report.

A review of the world literature since 1928 failed to disclose a case of endometriosis affecting the knee. In the case of a 32-year-old women, synovial sarcoma was suspected on the basis of the histologic findings on frozen section, but final pathologic sections showed endometriosis. Synovial sarcoma classically consists if malignant stoma containing gland-like clefts and is easily confused with endometriosis. Affecting the extremities, endometriosis is rare. The condition should new be added to the differential diagnosis of extremity swelling in actively menstruating women.