Histopathological and immunohistochemical findings of metastatic orbital tumors: A series of 7 cases

Metastatic orbital tumors are uncommon. A case series of 7 metastatic orbital tumors is presented herein. The primary sites included breast, skin (sweat gland carcinoma) and prostate. Accurate pathological diagnosis with an immunohistochemical panel is crucial to identify the primary site based on the specimens of the metastatic site. Metastatic orbital tumors from cutaneous origin, particularly sweat gland carcinoma, are very rare. In addition, sweat gland carcinomas like mucinous carcinoma and signet-ring cell/histiocytoid carcinoma are difficult to distinguish histopathologically from the carcinomas of breast origin. Moreover, well-known breast markers, GATA3 and BRST2 (GCDFP-15), could be a diagnostic pitfall due to positivity for the cutaneous sweat gland carcinomas. This report emphasizes the careful interpretation of immunohistochemical profiles, the clinical information of past medical history, and the systemic clinical work-up all of which are imperative for the final diagnosis.