Metastatic small cell carcinoma masquerading as orbital myositis.

A case of discrete metastases to an extraocular muscle from a silent small cell carcinoma is described. Clinically, diagnostically, and pathologically this masqueraded as orbital myositis. It was not until a full thickness muscle biopsy was obtained that the diagnosis was realized. The need for deep biopsy is stressed. Discrete metastases to an extraocular muscle without other orbital soft tissue involvement is rarely reported. This is the first reported case from a small cell primary tumor. Metastatic orbital disease is discussed.