Abstract

Periocular histiocytoid/signet-ring cell carcinomas are rare tumors that may be primary or metastatic. The distinction of primary from metastatic histiocytoid carcinomas is challenging. Metastatic tumors may show bilateral involvement and are usually of breast or, less commonly, gastrointestinal tract origin. The histogenesis of primary carcinomas is controversial, but most evidence points to apocrine glands or glands of Moll. Our patient was a 76-year-old female with a left orbital mass. Her past medical history was negative for carcinoma. Biopsy revealed infiltrating cells in the dermis and subcutis with a histiocytoid to signet-ring cell appearance. Immunohistochemistry showed positivity for CK7, GATA3, and E-cadherin, while CK20, MUC5AC, GCDF-15, ER, PR, synaptophysin, and chromogranin were negative. Subsequent clinical workup revealed omental caking. An omental biopsy showed H&E morphology similar to the left orbital mass. Immunohistochemistry showed positivity for CK7, TTF-1, and Napsin-A, whereas GATA3 and mammaglobin were negative. Primary histiocytoid carcinoma of the eyelid/orbit is typically GATA3 negative but has been reported to be positive in at least one case in addition to ours. However, GATA3 cannot be used as a reliable marker to distinguish a primary from a metastasis. The primary site of this lesion remains uncertain with no obvious internal malignancy on CT scans, but given omental caking, a gastrointestinal primary seems most likely. With eyelid or periocular histiocytoid carcinomas, diagnostic algorithms require a thorough clinical and radiological examination to rule out metastatic carcinoma. Many dermatopathologists evaluate ocular and eyelid lesions and should be aware of this rare entity.