膵囊胞性疾患の病理―分類と鑑別

New Classification of Cystic Lesions of the Pancreas

要旨　画像診断の進歩に伴い，膵囊胞の発見頻度は増加したが，従来の膵囊胞分類では，良性非腫瘍性囊胞の多くを貯溜囊胞としか表現できず，囊胞の肉眼・組織形態を推定できない，という問題が生じてきた．これらを解決するために，対象147上皮性膵囊胞(43例)を，肉眼所見で単房性と多房性に分け，更に組織所見(上皮の種類とその割合)で固有上皮型(28囊胞)，固有・粘液上皮混合型(19囊胞)，固有・扁平上皮混合型(1囊胞)，粘液上皮型(27囊胞)，扁平上皮型(2囊胞)，粘液・扁平上皮複合型(2囊胞)，腺腫型(3囊胞)，癌型(65囊胞)とに分類した．更に対象を囊胞径，粘膜高，囊胞房の点から検討し，腫瘍型囊胞と非腫瘍型囊胞の肉眼的鑑別を試みた．その結果，前者は囊胞径が大きく，粘膜高が高く，多房性であるという特徴を有していることが明らかとなった．

　Recent progress in various imaging techniques has led us to increased recognition of cystic lesions of the pancreas. Prior classifications of these lesions, however, have not been neccesarily appropiate in defining them. In this study, 147 cystic lesions found in 43 patients were divided into eight groups, based on the histological nature of the lining epithelium, i.e., the proper epithelium type (28 lesions), mixed proper and metaplastic mucous epithelium type (19 lesions), mixed proper and metaplastic squamous epithelium type (1 lesion), metaplastic mucous epithelium type (27 lesions), metaplastic squamous epithelium type (2 lesions), combined metaplastic mucous and squamous epithelium type (2 lesions), adenoma type (3 lesions), and carcinoma type (65 lesions).

　Moreover, the macroscopic appearance, unilocular or multilocular, was added to the classification. With this new classification, more detailed division of benign cysts formerly called retention cysts was possible and seemed more practical. In addition, this study demonstrated that neoplastic cysts tended to be larger and multiloculated. Also, the lining epithelium of the neoplastic cysts were taller than that of the non-neoplastic cysts.