Endoscopic mucosal resection of a rectal malakoplakia in a healthy adult

Malakoplakia in the gastrointestinal tract is rare in healthy young people without underlying disease. Sufficient tissue is required for accurate diagnosis. We describe a malakoplakia that developed in a healthy young woman and was treated by endoscopic mucosal resection (EMR). A 40‐year‐old woman with a history of taking oral contraceptives until one year earlier was referred to our hospital with anal bleeding and constipation. A colonoscopy carried out at our another hospital 18 months earlier disclosed no abnormal findings. Colonoscopy at presentation revealed a yellowish‐white tumor, 5 mm in diameter, in the rectum. The lesion was slightly protruded and had a smooth flat surface, without erosion or ulceration. EMR was carried out for a definitive diagnosis. Histopathological examination showed that the tumor contained granular histiocytes, positive for CD68 and negative forcytokeratin (AE1/AE3). Several histiocytes contained intracytoplasmic round bodies (Michaelis–Gutmann bodies), which reacted positively with periodic acid‐Schiff and calcium (Von Kossa) stains. Intracytoplasmic Escherichia coli (von Hansemann bodies) were identified by Giemsa staining. Based on these results, the tumor in the rectum was diagnosed as a malakoplakia. Following EMR, the patient did not receive further treatment for malakoplakia because she had no symptoms associated with malakoplakia. She has been well for more than 9 months, with no symptoms of disease. Awareness of colorectal malakoplakia is important in patients taking steroids, including oral contraceptives.