Chronic Schistosomiasis in a Patient with Rectal Cancer

A previously healthy 66-year-old Filipino woman presented with a 2-month history of intermittent rectal bleeding, pain with defecation and a 9-lb weight loss. A 5-cm anal tumor, found on colonoscopy and confirmed by magnetic resonance imaging scan ( Figure 1 ) was surgically removed. Histopathologic examination of the specimen showed a moderately differentiated adenocarcinoma and heavily calcified, nonviable Schistosoma japonicum ova in the rectum, vessels, and lymph nodes (eggs roughly 60 µm in diameter, oval to round in shape with no spine or a small barely detectable subterminal spine). The eggs were predominantly submucosal ( Figure 2 ), with no predilection for carcinomatous versus non-carcinomatous bowel ( Figure 3 ). The patient immigrated to the United States when she was 8 years old (she grew up in rural Philippines, a known endemic region) and had never been to a Schistosomiasisendemic region since that time. She had, therefore, acquired the infection almost 60 years ago in the Philippines. We speculate that the inflammation caused by chronic S. japonicum infection contributed to the development of rectal cancer. An association between urinary bladder cancer and S. hematobium has been well established 1 ; a similar association