Differential diagnosis of polypoid lesions that can mimic adenoma
• Mucosal prolapse, solitary rectal ulcer syndrome, colitis cystica profunda, eroded polypoid hyperplasia: These are seen in rectosigmoid colon as an ulcerated or a polypoid lesion in patients with history of constipation or straining during defecation. The histologic examination shows surface erosion, epithelial hyperplasia with distorted and dilated crypts, vertical stranding of muscle fibers in the lamina propria, fibrosis, and lymphoplasmacytic infiltrate. Inflammatory cloacogenic polyps are present at the anorectal junction and show similar histologic characteristics with both squamous and colonic epithelia.
• Lymphoid polyps: These are benign reactive lymphoid aggregates in the mucosa.
• Inflammatory polyps : Generally associated with IBD or diverticulitis and consist of marked inflammation in the lamina propria with granulation tissue and fibrosis. The mucosal lining may show regenerative change or erosions.