Possible associations of rectal carcinoma with Schistosoma japonicum infection and membranous nephropathy: a case report with a review.

We report the first case of rectal carcinoma associated with S. japonicum and membranous nephropathy. A 57-year-old Japanese man noticed narrowing of his feces. He had lived in Yamanashi prefecture, an endemic area of S. japonicum. He had suffered from nephrotic syndrome for about 1 year. Barium enema study showed a severe stricture in the upper rectum and biopsy specimens from the tumor demonstrated well differentiated adenocarcinoma and many ova of S. japonicum. Sonography of the liver showed a network pattern and a linear high echoic area. Low anterior resection with incisional biopsy of the liver and the right kidney was performed. Histopathological findings showed well differentiated adenocarcinoma and schistosomal ova. The total number of ova in the resected colon amounted to 15,133, consisting of 2243 inside and 12,890 outside the carcinoma. The nearer to the carcinoma the area was, the higher was the density of ova. The findings of light microscopy and electron microscopy of the biopsy specimen from the kidney were compatible with membranous nephropathy (stage II). This case suggests that schistosomal ova have some effect on carcinogenesis and nephrotic syndrome. In patients with nephrotic syndrome of unknown cause, especially in inhabitants of endemic areas of S. japonicum, gastrointestinal malignancy should be ruled out as an etiological factor. Sigmoidoscopy would be useful for colorectal carcinoma surveillance in S. japonicum patients.