Inflammatory Myoglandular Polyps Presenting With Diarrhea

CASE REPORT

A 49-year-old man without a pertinent medical history reported a 7-month history of diarrhea occurring 6–8 times per day. He reported formed bowel movements before developing watery stools with nocturnal symptoms. He denied new diet changes, new medications, and recent travel. Stool studies were reportedly negative, and he had mild hyponatremia. His symptoms did not improve with the maximum dose of loperamide. He subsequently underwent colonoscopy, which demonstrated 3 large (>20 mm) “adenomatous-appearing” polyps and greater than 10 large polyps of unclear etiology, all in the descending colon. He presented to our academic institution for endoscopic mucosal resection. However, on our endoscopic inspection, the sigmoid and descending colon had >20 subpedunculated polyps without distinct adenomatous characteristics, measuring 15–30 mm (Figure 1). Owing to the number of lesions, definitive endoscopic therapy was not possible, and the polyps' proximal extent was tattooed. Two representative polyps were resected (Figure 2). Histopathologic examination was consistent with inflammatory myoglandular polyps (Figures 3 and 4). After a multidisciplinary discussion, colonic resection was deemed necessary because of polyp number and persistent diarrhea. Laparoscopic extended left hemicolectomy with primary anastomosis was performed without issue. At his 1-month surgical follow-up, he was doing well and reported complete resolution of diarrhea.

Figure 1.

Large sigmoid colon polyp on endoscopic view (single polyp shown but multiple polyps found in this area).

Figure 2.

A large spherical, red polyp located in the sigmoid.

Figure 3.

Hyperplastic and cystically dilated crypts surrounded by radially arranged smooth muscle bundles. The surface of the polyp shows fibroinflammatory exudate and granulation tissue (black arrow).

Figure 4.

Mucin-filled cysts within smooth muscle fibers.

Inflammatory myoglandular polyps (IMGPs) are a rare clinical entity.¹ Most IMGP cases have been described in middle-aged men.^1,2 The 3 distinct histologic features of IMGP are inflammatory granulation in the lamina propria, smooth muscle proliferation, and hyperplastic glands with some cystic dilation.¹ IMGPs are usually solitary asymptomatic lesions. When symptomatic, IMGPs can present with positive fecal occult blood,¹ hematochezia,³ or rarely intussusception.⁴ We describe one of the first cases in the literature detailing multiple large IMGPs in the descending colon resulting in diarrhea. We suspect his diarrhea was related to the large surface area that had increased granulation tissue and smooth muscle proliferation, likely decreasing the absorptive capacity of the distal colon. Similar to our case, IMGPs are predominately found in the descending colon, with most described as semipedunculated to pedunculated. Endoscopically, these polyps are described as red, usually spherical, and smooth. Nevertheless, the correct diagnosis of IMGPs requires pathology for confirmation because similar clinical entities (inflammatory fibroid polyps, Peutz-Jeghers-type polyps, or juvenile polyps) have increased malignant potential compared with IMGPs.⁵ Most isolated IMGPs can be managed endoscopically. However, surgical management should be considered when endoscopic management is not possible.

DISCLOSURES

Author contributions: C. Fritz wrote the manuscript and is the article guarantor. P. Navale, M. Mutch, and V. Kushnir revised and approved the final manuscript.

Financial disclosure: C. Fritz is supported by T32 DK007130.

Informed consent was obtained for this case report.