A 12-year-old boy was referred with a 4-week history of intermittent bright-red lower gastrointestinal tract bleeding. He denied abdominal pain, nausa, vomiting, diarrhea, and weight loss. He had not experienced fever, and had had no known infectious exposures. He described his stools as formed, nonpainful, and 1 to 2 per day. Blood was noted on the stool, in the toilet water, and on the tissue. His physical examination was completely normal. Specifically, he had no freckling of the lips of buccal mucosa, no skin lesions, and no bony or soft tissue tumors. Family history was negative for adenomatous polyposis coli, juvenile polyposis coli, and isolated polyps. Complete colonoscopy was performed, and a polyp measuring 2 cm in greatest diameter on a 2 cm-long stalk was encountered 30 cm from the anus(Fig. 1). No other polyps, masses, or mucosal abnormalities were noted. The polyp was submitted for histologic studies. Diagnosis is: Classical juvenile polyp Mixed juvenile and adenomatous polyp Peutz-Jegher polyp Lymphoid polyp Villus adenoma ANSWER: see page 225. Clinical Quiz, continued from page 174 Answer: The polyp contained features of a juvenile polyp in juxtaposition with adenomatous change (Fig. 2) and with adenocarcinoma in situ (Fig. 3). The stalk was free of adenomatous change. Comment: While many large series have failed to identify the development of adenocarcinoma in patients with solitary juvenile polyps, Grybowski (1986) warned that not all juvenile polyps are benign. She described a 4-year-old child with a solitary juvenile polyp with adenomatous change, and an 8-year-old boy with adenomatous change in one of a cluster of polyps found in the left colon. She emphasized that neither patient had a family history of adenomatous polyposis coli or colorectal cancer. Her cases and the case presented here emphasize the need for careful examination of all polyp materials in order to identify patients at risk.FIG. 1FIG. 2FIG. 3