Rectal Schistosomiasis and Adenocarcinoma

Abstract Introduction/Objective Schistosoma infestation has been implicated by the International Agency for Research on Cancer as an etiology for several cancers such as colon, liver, and bladder. S. japonicum is classified as a probable carcinogen in humans (class 2B). These trematodes may cause chronic infection in the affected organ leading to the trend of “inflammation-adenoma-carcinoma”. There is rising evidence that infection with Schistosoma japonicum is correlated with the liver and colorectal carcinoma in endemic Asian countries. We herein present a case of rectal adenocarcinoma associated with Schistosoma as a possible causal factor. Methods/Case Report An 88-year-old-woman from China, currently living in United States for past six years, presented with rectal bleeding. Colonoscopy showed evidence of a rectosigmoid mass 2.2 x 1.0 x 0.3 cm. She underwent trans-anal excision of the tumor. Microscopic examination showed moderately differentiated adenocarcinoma with tumor invading the muscularis propria (pT2). There were numerous oval / round calcified eggs (30 - 46 microns) with minute subterminal or no spine morphologically consistent with Schistosoma japonicum associated with granulomatous and foreign body giant cell reaction, fibrosis, and tissue eosinophilia. She was treated with Praziquantel and is currently undergoing endoscopic surveillance for recurrence. Results (if a Case Study enter NA) N/A Conclusion Patients with chronic Schistosoma japonicum infection have 3 times increased risk of developing colorectal cancer than those with no previous exposure to schistosomal infection. We believe that chronic S. japonicum infection is the likely etiology of rectal cancer in our patient. Physicians should be aware of such associations, especially for immigrants from endemic areas, to facilitate accurate diagnosis and management.