Since the epochal work of von Recklinghausen 1 in 1882, there has been much discussion about the origin and nature of neurofibromatosis. Although the literature contains hundreds of reported cases of multiple neurofibromatosis, the condition is not of frequent occurrence in the experience of any one physician. Malignant transformation of these cutaneous or deep-seated nodules is of unusual interest, especially when one is able to follow a case like the one here reported from the stage of benign neurofibroma to that of spindle cell sarcoma. REPORT OF CASES Case 1. —History. —W. F., a white man, aged 28, was admitted in 1927 to the service of Dr. George E. Beilby, Albany Hospital, with the chief complaint of soreness in the right side of his neck and lumps on both sides of his neck. Except for the usual diseases of childhood, his general health had been excellent. In 1920, his tonsils