The fact that diverticulitis and diverticulosis may mask or mimic carcinoma was first stressed by Moynihan,17 who, in 1906, presented six such cases to the Clinical Society of London. Since then, numerous observers, including Mayo and Blunt,14 Jones,10 Mayo and Delaney,15 and Edwards,6 have recognized this problem. Pemberton19 noted that 25% of 104 of his cases could not be distinguished between carcinoma and diverticulitis. In 30 patients Graham9 reports that the roentgen diagnosis was correct in 57%. Jones10 stated that the first case of diverticulitis ever recorded at the Massachusetts General Hospital had to be changed in three months to carcinoma.
While in most cases the diagnosis is relatively easy, at the Massachusetts General Hospital in a series of resections in which the preoperative diagnosis was cancer 18% of the specimens were proved by the pathologists to be diverticulitis. To err in