Limitations of biopsy in preoperative assessment of villous papilloma.

Between January 1975 and December 1979, 58 patients were diagnosed as having villous papilloma of the large bowel. A retrospective review was performed and all histologic specimens were re-examined by one gastrointestinal histopathologist (H.T.). On review, 19 (23 per cent) lesions were reclassified as not being villous papilloma. Results of preoperative biopsy examinations were misleading in 13 of the 29 patients who had biopsy procedures reported by any member of the histopathology department. When the assessment of malignancy in the initial biopsy specimens was compared with that of the final histologic diagnosis, there were ten (34 per cent) false-negative and three (10 per cent) false-positive reports. Even when the excised specimens were reviewed for malignancy by a specialist gastrointestinal histopathologist, there were seven (24 per cent) false-negative results.