The treatment of the pelvic tumors depends of their histological nature. Some of them require only one medical treatment without recourse to surgery. We report two rare cases of pelvic tumors occurring in young adults. For the first case, actinomycosic nature was related to the histological study of the surgical biopsies. Concerning the second case, the lymphatic nature of a tumor of the low rectum was retained on the immunohistochimic study of the endoscopic biopsies. The evolution was uneventful in the two cases after a medical treatment containing penicillin G or a chemotherapy. We discuss at the time of these two observations the diagnostic difficulties and the therapeutic methods of these rare affections.