Signet cell adenocarcinoma of the rectum metastatic to the orbit.

A 24-year-old man developed abdominal carcinomatosis from signet cell carcinoma of the rectum. His only distal metastasis involved the superior orbit. Orbital pathology showed signet cells with a characteristic immunopathologic pattern. No hereditary syndrome was found. The authors identified only 5 cases in the literature describing colorectal adenocarcinoma metastatic to the orbit, with 2 showing histopathology. The authors believe that this rare case represents the first illustrating bona fide signet cell colorectal cancer involving the orbit.