Schistosomiasis and signet ring cell carcinoma of the rectum.

A definitive link between Schistosoma hematobium infection and squamous cell carcinoma of the bladder has been identified. A weaker association between S japonicum infection and colorectal neoplasia has been proposed, although reports are limited to case reports, a case series, and epidemiologic studies. Virtually all cases presented in the literature describe intestinal-type adenocarcinoma occurring in association with S japonicum. We here describe a 40-year-old male Filipino patient with signet ring cell carcinoma of the rectum and evidence of infection by S japonicum.