Plexiform neurofibroma is a relatively uncommon but characteristic manifestation of neurofibromatosis. Two pelvic cases were found by CT in two young patients in whom it was the first fortuitous manifestation of the disease. The CT pattern, which seems to be in close relation with pathology, is described and illustrated. This pattern is so typical that there is no difficulty to establish the differential diagnosis. The question of sarcomatous transformation is more problematic by CT.
