An immunohistochemical study of perianal Paget's disease. Possible origins and clinical implications.

The histogenesis of perianal Paget's disease is controversial. A clinical and pathologic study was done of a patient with a history of adenocarcinoma of the rectum for whom a subsequent diagnosis of perianal Paget's disease was the sole manifestation of recurrent rectal cancer. Immunohistochemical techniques were used to compare and contrast the original rectal adenocarcinoma with the subsequent perianal skin recurrence confined to the epidermis. Both the rectal adenocarcinoma and the Paget's cells were positive for cytokeratin, epithelial membrane antigen, B72.3, and carcinoembryonic antigen and negative for gross cystic disease fluid protein-15, Leu-M1, CA 125, and S-100 protein. These findings, their relevance to the histogenesis of perianal Paget's disease, and the possible clinical implications are discussed.