Primary Signet-Ring Cell/Histiocytoid Carcinoma of the Eyelid: A "Binocle" Presentation of the "Monocle Tumor".

Primary cutaneous signet-ring cell carcinoma is a rare and aggressive neoplasm which diffusely involves dermis and subcutis of the eyelid or axillae. Neoplastic cells show a signet-ring cell or histiocytoid morphology in variable number, and can be found intermingled among collagen bundles, sparing the epidermis. This neoplasm typically appears in the eyelids of elderly men, in the form of a painless infiltration and swelling but with no other specific clinical feature, and frequently causes diagnostic retardation and worse prognosis. Frequent involvement of both eyelids of the same eye has given it the name of monocle tumor. Only 29 cases have been described in English literature to date, of which 7 developed metastases, mainly on regional lymph nodes. The authors present a case of involvement of contralateral eyelid, which has only been described previously in 2 cases. The immunohistochemical profile of the involvement in the contralateral eye, and the absence of other metastasis, suggest that it is locally spread from the initial lesion. However the possibility of being a second primary tumor or metastasis cannot be readily ruled out.