Malacoplakia in a colonic adenoma: case report.

We report a case of colonic malacoplakia in a tubular adenoma. A 67-year-old neurotic man had been treated with minor tranquilizers for 10 years. In January 1997, he underwent a health examination. Most of the tests performed were within normal limits, except the colonoscopy, which revealed a polypoid lesion in the left colon. A polypectomy was performed at that time. The histopathological study of the polyp showed a tubular adenoma with malacoplakia, characterized by an aggregate of numerous histiocytes containing Michaelis-Gutmann bodies in the lamina propria. A review of the English literature indicated that 35 cases of colonic malacoplakia have been documented. Colonic malacoplakia can occur in isolation or with diffuse or multiple involvement of the adjacent and unrelated diseased sites. The majority of cases are associated with other diseases, the most common being carcinoma of the colorectum. The association of colonic malacoplakia with adenoma is extremely rare and only 3 cases including our present case have been reported. We suggest that colonic malacoplakia is more common than usually suspected. A careful histologic examination is necessary.