An Unusual Etiology of Lower Gastrointestinal Bleeding, Small Intestinal Adenomyoma

Abstract

Introduction: Intestinal adenomyomas, also known as myoepithelial hamartomas, are benign lesions characterized by glandular structures lined by cuboidal or tall columnar epithelium and surrounded by smooth muscle bundles. Reported cases of adenomyoma of the gastrointestinal tract have been largely confined to the stomach and duodenum mainly involving the peri-ampullary region, with lesions distal to the duodenum occurring less frequently The majority of these cases were found incidentally on surgery or autopsy. Here we report a case of adenomyoma of the jejunum that presented with anemia. Case summary: A 62 year old woman with heartburn & cholecystectomy presented to an outside hospital for bronchial thermoplasty for treatment of asthma and was incidentally found to have anemia. EGD and colonoscopy were negative for a source of bleeding. Capsule endoscopy revealed a pedunculated polyp in the distal jejunum. Endoscopic removal of the polyp in the distal jejunum was completed by double balloon enteroscopy. Grossly (Figure 1), the lesion was a polypoid shaped mass measuring 0.9 x 0.8 x 0.6cm. Microscopically, it was a well circumscribed submucosal lesion composed of variably sized glandular structures surrounded by smooth muscle bundles. The glandular structures showed pyloric morphology and were lined by cuboidal or columnar epithelium with interspersed goblet cells and occasional Paneth cells (Figure 2). Immunostains were performed with appropriate controls (Figure 3). The lesions epithelial component was strongly and diffusely positive for CK7 and CK19 and weakly positive for CDX2, but negative for CK20. The smooth muscle component was positive for desmin and alpha-SMA. Ki-67/MIB-1 highlighted rare lymphocytes in the lesion and basal cells of the small intestinal mucosal epithelium (Figure 4). All features supportied a final diagnosis of adenomyoma.Figure 1Figure 2Figure 3Discussion: Adenomyoma of the small intestine is an extremely rare tumor largely unknown to most clinicians. While typically asymptomatic, symptoms of intestinal adenomyoma vary depending on size, location, and patient age. In our patient this lesion was likely the source of chronic GI bleeding manifesting as anemia. The prognosis of adenomyoma is excellent, with no evidence of recurrence or metastatic transformation in reported cases. Treatment of asymptomatic or bleeding adenomyomas is simple resection.