Analysis of Clinicopathological Features of Cap Polyposis, in Comparison with Mucosal Prolapse Syndrome Takashi Yao 1 , Mikihiro Esaki 2 , Hideki Koga 3 , Akinori Iwashita 4 1Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University Keyword: cap polyposis , 粘膜脱症候群 , 線維筋症 pp.631-639
Published Date 2002/4/25
DOI https://doi.org/10.11477/mf.1403103506
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 The Clinicopathological features of cap polyposis were reviewed, comparing them with mucosal prolapse syndrome (MPS). Cap polyps were distributed not only in the rectum but also in the sigmoid and descending colon, while lesions of MPS were restricted to the rectum. Histologically, there was a difference between cap polyposis and MPS in the degree and distribution of inflammation and the degree of fibromusculosis. Microvascular abnormalities such as the presence of muscularised capillaries, thrombosis and fibrin insudation and the presence of diamond-shaped crypts are characteristic in MPS, while they are rarely seen in cap polyposis. analyzing the histological features of cap polyposis, we speculated about its histogenesis and progression as follows: 1) First, the superficial and localized inflammation arises in flat mucosa. 2) Next, it grows into an elevated lesion (polyp) with elongation of crypts, mild fibromusculosis, overgrowth of granulation tissue, congestion and ischemic change of superficial crypts. 3) The aggregation of small cap polyps makes a large sessile polyp. 4) In addition, the mucosal prolapse increases the degree of elongation of crypts and fibromusculosis. In conclusion, cap polyposis and MPS are essentially different in histogenesis and clinicopathological features, but mucosal prolapse may be associated with the progression of cap polyposis.

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