This is a report of a case of papillary cystadenocarcinoma of the so-called lateral aberrant thyroid in which a similar neoplasm of microscopic size was found in the homolateral lobe of the thyroid. The latter neoplasm was disclosed only by total embedding of the lobe, as urged in consultation by Dr. Fred. Stewart and Dr. Frank W. Foote, of Memorial Hospital, based on the reported experience1 in that institution. CASE REPORT On Jan. 7, 1949, a 45 year old white man was examined by one of us (G. De Y.). Two months previously, while shaving, he felt a lump in the lower right side of his neck. Since then it had become larger, but no pain or tenderness was present. A firm mass about 3 cm. in diameter was palpable partially at the back of the lower end of the right sternocleidomastoid muscle. It was movable and nontender. There