Patterns of Schistosoma haematobium egg distribution in the human lower urinary tract. III. Cancerous lower urinary tracts.

The distribution of S. haematobium eggs in urinary bladders containing tumors and removed at surgery has been studied; the majority of these tumors are well differentiated squamous cell carcinomas. The same three anatomic patterns of egg accumulation described in part I of this series (noncancerous lower urinary tracts) were found in these cancerous bladders, but, in addition, most of the tumors were surrounded by a collar of heavy S. haematobium egg deposition. The egg burdens in these collars were, on the average, twice the average egg burden in the remainder of the urinary bladder. These collars do not seem to be artifacts created by growth of the tumor and subsequent displacement of the adjacent normal tissue, creating a region of heavy egg concentrations; rather, these heavy S. haematobium egg concentrations seem to act as promoters of urothelial carcinogenesis.