Postinflammatory polyposis (PIP) of the colon: the radiologic-pathologic spectrum.

The radiologic-pathologic spectrum of postinflammatory polyposis (PIP) of the colon and the evolution of the radiographic appearance of PIP over time were retrospectively studied in 27 patients (21 with ulcerative colitis, 6 with Crohn disease). Two general patterns of radiographic evolution were recognized: progression from active, ulcerating disease to mucosal healing with formation of PIP, and interruption of healing with PIP by recrudescence of active ulceration with inflammatory pseudopolyposis. In these latter cases, disease activity recurred in the same areas in which healing with PIP had been recognized. A review of all pathologic material indicated that the histopathology of PIP is varied and depends, to a large extent, on polyp size.