THE PATIENT whose history is reported in this communication presented a tumor of islet tissue which was of interest for the following reasons: It did not produce hyperinsulinism; it was unusually large in size, and it had undergone cystic degeneration, which is rare in growths of this type. REPORT OF A CASE History. —On May 12, 1942, a 65 year old housewife was admitted to the Roosevelt Hospital complaining of pain in the left upper region of the abdomen. Except for a hysterectomy for uterine fibroids twenty years previously, there had been no medical or surgical illnesses of any significance. In April 1942, about four weeks prior to her admission, the patient began to have a constant dull ache in the epigastrium and left upper quadrant. Within a few days she began to have occasional vomiting, which soon became persistent. During the ensuing three weeks she had retained no solid