Gastrointestinal: Inflammatory myoglandular polyp of the colon

Abstract

An inflammatory myoglandular polyp of the large bowel is a rare but distinct clinical entity that was first described by Dr S Nakamura and others in 1992. It is characterized histologically by inflammatory granulation tissue in the lamina propria, proliferation of smooth muscle and hyperplastic glands which sometimes show cystic dilatation. The typical endoscopic appearance is that of a pedunculated spherical polyp with a smooth surface and patchy redness that resembles a ripe strawberry. There may also be a patchy mucous exudate. Thus far, only a small number of cases have been reported and the pathogenesis and natural history remain unclear. We describe the endoscopic and histological findings of an inflammatory myoglandular polyp in the distal transverse colon.A 42-year-old Japanese man was investigated because of a positive fecal occult blood test. Barium enema radiographs revealed two colonic polyps: one in the distal transverse colon and one in the sigmoid colon. At colonoscopy, the polyp in the transverse colon was approximately 10 mm in diameter with a spherical shape, pedunculated base and a smooth surface as shown in Figure 1. Red areas were noted on the surface of the polyp. Histological evaluation revealed hyperplastic glands and an inflamed and widened fibromuscular stroma with lymphoid follicles ( Fig. 2; HE ×25). The appearance was consistent with an inflammatory myoglandular polyp. The polyp in the sigmoid colon was a small tubular adenoma. Inflammatory myoglandular polyps need to be distinguished from Peutz-Jegher-type polyps, juvenile polyps, inflammatory polyps, inflammatory cap polyps, and polyps associated with mucosal prolapse, sometimes involving colostomy sites.

Lobulated inflammatory myoglandular polyp in the ascending colon observed by magnifying endoscopy and treated with endoscopic polypectomy

“…According to Fujino et al [8] , a review of the literature revealed 48 cases of IMGP in the large intestine up to 2001. However, recent advances in diagnostic techniques have enabled us to identify small and asymptomatic polyps, and reports on IMGP of the colon have been increasing [9,10] . Fujino et al [8] described that the macroscopic appearance was the pedunculated type in 83.3% of cases.…”

“…Endoscopic characteristic findings are as follows: (1) pedunculated or semipedunculated, (2) red and (3) smooth, spherical and hyperemic surface with patchy mucous exudation and erosion [8,9] . IMGPs should be distinguished from other colorectal polyps such as inflammatory fibroid polyps (IFP) [10,13] , Peutz-Jeghertype polyps or juvenile polyps [10,11] . However, the correct endoscopic diagnosis of colorectal IMGP can seldom be made.…”

“…Thus, IMGPs of the large intestine are predominantly in the distal colon [8,9] . IMGPs in the colon are usually asymptomatic and often detected incidentally on barium enema or endoscopy [8][9][10] . Another review of the literature revealed that the main clinical feature of colorectal IMGPs is hematochezia [10,11] .…”

“…IMGPs in the colon are usually asymptomatic and often detected incidentally on barium enema or endoscopy [8][9][10] . Another review of the literature revealed that the main clinical feature of colorectal IMGPs is hematochezia [10,11] . Endoscopic characteristic findings are as follows: (1) pedunculated or semipedunculated, (2) red and (3) smooth, spherical and hyperemic surface with patchy mucous exudation and erosion [8,9] .…”

“…Only a small number of cases have been reported, and its pathogenesis and natural history remain unclear [8][9][10][11][12] . Herein, we describe a relatively rare case of loburated-type IMGP in the ascending colon causing hematochezia.…”