Histiocytoid eccrine sweat gland carcinoma of the eyelid: report of a case

Summary This report describes the 12th documented case of histiocytoid, diffuse or signet‐ring cell eccrine sweat gland carcinoma of the eyelid, a rare neoplasm that characteristically affects older men and mimics distant metastasis. Clinically, the patient was thought to have a colonic metastasis. Histologically, the neoplasm comprised sheets and cords of polygonal, eosinophilic cells, with dispersed larger, rounded single cells resembling histiocytes, and cells with cytoplasmic lumina or a signet‐ring appearance. Occasional duct formation was also seen. The features were reminiscent of both the histiocytoid and lobular variants of breast carcinoma. Ultrastructurally, the presence of nonintestinal type microvilli with a length : width ratio in excess of 16 were consistent with an eccrine origin, but also raised the possibility of metastatic mesothelioma. However, a metastatic lesion was excluded by clinical and imaging investigations. There has been no recurrence 3 years after primary excision.