The finding of an orange-yellow nodule in a tissue or organ is usually of arresting interest. Orange plaques on eyelids are a common and striking occurrence, and similar skin tuberosities are occasionally seen on the knees, elbows and hands; golden-brown nodules sometimes develop about tendon sheaths and joints; rarely a sinus tract discharges an amazing orange pus and leads to a similarly colored granuloma; the dull yellow of a hypernephroma sometimes displays a distinctive reddish-brown nodule, and a carcinoma of the prostate is discolored very infrequently by a similar process. Finally, there very rarely occur generalized golden-yellow infiltrations as the most striking effect of an unusual constitutional deficiency. To this miscellaneous group of clinical and anatomic conditions the term "xanthoma," introduced by Lebert in 1845 and again by W. F. Smith in 1869, to denote a yellow fibrous tumor, has been rather indiscriminately applied. The common denominator in all has