Histological findings. Polyp's whole picture, showing cystic dilatations embedded in the fibromuscular stroma (A). Low power view of inflammatory granulation tissue and engorged capillaries in the lamina propria, hyperplastic glands with cystic dilatations and proliferation of smooth muscle from muscolaris mucosae (B, C). Diffuse positive immunostaining of smooth muscle actin (D). (A, B, C: hematossilin-eosin staining, A 1:1, B 2,5× obj, C 4× obj; D: anti-actin immunoperoxidase, 4× obj).