Multiple metaplastic (hyperplastic) polyposis of the entire colon is an unusual entity which presents with a radiologic pattern resembling familial polyposis. It is important that the radiologist be aware of this entity and distinguish between these 2 conditions. The radiologic, pathologic, and clinical features of this condition are reviewed and an illustrative case is presented.Metaplastic (hyperplastic) polyps are a common finding in the rectal mucosa of subjects more than 40 years old [1,2], and were present in up to 82% of patients in a surgical and autopsy study by Arthur [3]. The presence of large numbers of these polyps so that almost the entire colonic mucosa appears studded with them is rare. We recently studied a young man with this unusual form of the disease.
Case ReportA 26-year-old white man complaining of fatigue was found to be anemic (Hematocrit 30%) 2 weeks prior to admission to St. Vincent Hospital. He denied melena, diarrhea, constipation, nausea, or vomiting. His family (parents, a sister, and 3 brothers) had no history of polyps or other gastrointestinal disorders except for hemorrhoids and an anal polyp in the father. On admission his hematocrit was 24.1% but was 20.7% one day later; his stools were guaiac positive. Upper gastrointestinal and small-bowel series were within normal limits. Proctoscopy to 14 cm revealed several clusters of small polyps. A barium enema demonstrated the colonic mucosa to be studded with innumerable tiny polyps measuring from pinhead size to 0.5 cm. A colonoscopy to the cecum showed numerous small polyps and raised areas of mucosa throughout the colon, more prominent in the rectal area. Biopsies showed colonic mucosa with slight thickening but no adenomatous changes. A second proctoscopy with biopsy performed 1 week Address reprint requests to." M.L. Janower, M.D., Department of Radiology, St. Vincent Hospital, Worcester, MA 01604, USAlater showed similar changes. The stool became guaiac negative and the patient was discharged.The patient was lost to follow-up until 26 months later when he presented again with blood in his stool. His hematocrit was 44%, hemoglobin 15%, and stocfl guaiac was positive. A repeat barium enema again revealed a uniform pattern of tiny mucosal excrescences throughout the length of the colon (Fig. 1). Colonoscopy revealed hundreds of tiny polypoid structures in the rectum and throughout the length of the colon, but more proximally the distinct polypoid appearance decreased and at the cecum there were merely thickened mucosal folds. The color of the polyps was similar to that of the intervening normal mucosa. Multiple biopsies were performed and showed metaplastic (hyperplastic) polyps (Fig. 2). There was no evidence of adenomatous change. A bone survey -including hand, wrist, femur, tibia, fibula, and skull was normal. The patient was discharged with a diagnosis of diffuse metaplastic (hyperplastic) polyposis of the colon. Close follow-up is planned.
DiscussionIn 1962 Morson [2] introduced the term "metaplastic polyp", since he consider...
