Rectal polypoid lesion with a nodular surface.

Question: A 60-year-old man presented to the Gastroenterology Clinic at Kosin University Gospel Hospital for the management of abnormalities detected on colonoscopic examination. He underwent colonoscopic examination for a health checkup at another hospital, 2 months prior to presenting to this hospital. He denied abdominal symptoms, although he admitted to a habit of excessive straining during bowel movements. Colonoscopic examination revealed a rectal polypoid lesion measuring approximately 2.5 cm in size with a nodular surface, located 5 cm from the anal verge with convergent folds around it (Fig. A). EUS showed a homogeneous hypoechoic lesion originating from the submucosal layer (Fig. B). Malignancy could not be ruled out; therefore, endoscopic mucosal resection was scheduled for the removal of the lesion and for histopathological diagnosis. What is the diagnosis in this case?

Answer to the Images: Mucosal Prolapse Syndrome

The lesion showed a positive non-lifting sign in response to submucosal saline injection. However, endoscopic mucosal resection was performed successfully (Fig. C). The histopathological diagnosis was mucosal prolapse syndrome. As shown in Fig. D (H&E, ×100), fibromuscular obliteration of the lamina propria was observed with bundles of muscularis mucosa invading the lamina propria. The lamina propria showed inflammatory cell infiltration and a small quantity of hemorrhage.

Mucosal prolapse syndrome is an uncommon chronic inflammatory disorder attributable to chronic mechanical stimulation [1]. The diagnosis of this condition is important because it may be clinically indistinguishable from malignancy. Mucosal prolapse syndrome can be diagnosed based on a combination of the patient’s symptoms, clinical findings, and histopathological abnormalities. Therefore, thorough examination of medical history is important. The pathogenesis of this condition is not well-established; however, chronic straining during defecation and difficulty initiating defecation might cause direct mucosal trauma with consequent formation of an ulcer or a polypoid lesion.

Mucosal prolapse syndrome includes solitary rectal ulcer syndrome, rectal prolapse, proctitis cystica profunda, and inflammatory polyps [2]. The common endoscopic findings are ulcerated, polypoid, or flat and elevated-type lesions [3]. Patients usually present with the passage of blood and/or mucus during defecation, as well as abdominal pain and/or constipation [4]. The characteristic histopathological findings are fibrous obliteration of the lamina propria, thickening of the muscularis mucosa, and distortion of the crypt architecture [5]. The treatment of mucosal prolapse syndrome primarily depends on the severity of symptoms, and asymptomatic patients may not require any treatment.