Metastatic thyroid carcinoma masquerading as lacrimal gland tumor.

A 56-year-old woman presented with orbital signs and symptoms suggestive of lacrimal gland tumor. An excised biopsy specimen was obtained and showed glandular tissue, which could be confused with lacrimal gland acini. Closer microscopic examination and immunohistochemical studies revealed a metastatic tumor of thyroid gland origin. Initially, there was no identifiable nodule in the thyroid, but 3 months later a thyroid nodule was found by ultrasound and radioisotope scan. The histopathologic appearance of the thyroid nodule was similar to that found in the orbit. This case demonstrates the usefulness of immunohistochemistry in establishing a diagnosis when the microscopic appearance is inconclusive.