A rare case of primitive epithelioid leiomyosarcoma of the conjunctiva

PURPOSE: To describe a rare case of conjunctival leiomyosarcoma initially diagnosed as a poorly differentiated squamous cell carcinoma. METHODS: Clinical, light microscopic, immunohistochemical, and ultrastructural findings are reported. RESULTS: A 56-year-old Caucasian woman was referred with a history of a progressive, rapidly growing mass in her left eye. Biopsy of the mass and histology yielded a first diagnosis of a poorly differentiated conjunctival squamous cell carcinoma. Orbital exenteration was performed 2 weeks later. Macroscopically, the exenteration specimen showed a soft mass completely involving the conjunctiva and extending to the eyelids and orbital structures. Histological examination revealed a malignant tumour composed of atypical, predominantly epithelioid large cells. Immunohistochemical and ultrastructural studies combined with the light microscopic findings contributed to clarify the diagnosis of epithelioid leiomyosarcoma. The patient was started on chemotherapy and radiotherapy, but died a few months later from widespread metastases. CONCLUSIONS: primary involvement of the orbit by a leiomyosarcoma is rare, but this eventuality should be considered in the differential diagnosis of rapidly growing orbital and conjunctival masses.