In accordance with the classification accepted by Thannhauser and Magendantz,1Montgomery2and other investigators, primary essential xanthomatosis may be divided into two main types, xanthoma tuberosum and xanthoma disseminatum. The distinction between these forms rests on a variety of clinical and biochemical differences, which concern the cholesterol content of the blood as well as the type and localization of the cutaneous and visceral lesions. In xanthoma disseminatum there are numerous fine papules and plaques on the flexor surfaces of the extremities, especially in the axillary folds. The mucous membranes of the mouth, pharynx and larynx are often affected, and as a result of involvement of the pituitary gland there is frequent occurrence of diabetes insipidus. Thannhauser and Magendantz also associated with this disease involvement of the bones, lungs and brain and Schüller-Christian disease. The cholesterol content of the blood is usually normal in patients with this disease, which has been designated, therefore,