Histological classification of schistosomal egg induced polyps of colon and their clinical significance. An analysis of 272 cases.

272 cases of schistosomal egg induced polyps collected from mass-screening for colorectal carcinoma in Jiashan County were divided into 3 types: fibrous type (FT), mixed type (MT) and epithelial proliferative type (ET). The ET was characterized by crypt elongation, hypertrophy, variation in size, disorderly arrangement, as well as the high percentage of atypical hyperplasia (64.9%). The coexistence and transition between inflammatory reactive hyperplastic and neoplastic crypts were noticed. By HID/AB staining, sialomucins were increased in ET, CEA and PNA receptors detected by the ABC method were present in 18/20 and 6/18 of ET respectively. The mucin expression of ET was similar to that of adenomas. It is likely that a spectrum of ET, atypical hyperplasia and adenoma may exist. We suggest that the patients with ET, especially those with atypical hyperplasia, should be regarded as "risk group", and close follow-up is needed.