主膵管内に限局する微小な膵頭部癌の1例

Small Pancreatic Head Carcinoma Limited to the Main Duct, Report of a Case

要旨　一過性の左季肋部痛と血清アミラーゼの上昇を契機にERCPを施行し，内視鏡的膵管生検により術前診断された，主膵管内に限局する径5mmの微小な膵頭部癌の1切除例を経験した．患者は63歳，女性で，CEA，CA19-9は正常，超音波検査，CTで体部主膵管の軽度の拡張を認めた．ERCPでは主膵管内に類円形の透亮像が描出され，内視鏡的膵管生検で組織学的に癌と診断された．血管造影では癌の所見を認めなかった．癌は主膵管内で乳頭状に発育し，組織学的には低分化型腺癌と考えられた．また，主病巣と離れた膵管にも異型上皮がみられ，多中心性の癌発生を否定できなかった．本症例の概要と共に，膵癌早期診断の手法について若干の文献的考察を加え報告した．

　A 63-year-old female was seen because of transitory left hypochondralgia and elevated serum amylase level. Her serum CEA and CA19-9 levels were within normal limits. Ultrasound (Fig. 1) and computed tomography (Fig. 2) were negative except for slight dilatation of the main pancreatic duct. ERCP (Figs. 3 a-c) showed an intraluminal filling defect in the main pancreatic duct, and histological examination of the biopsy specimen obtained from the pancreatic duct (Fig. 3d) revealed carcinoma (Fig. 4). Angiography was negative for the findings suggestive of malignancy (Fig. 5).

　Macroscopic and histological examinations of the resected specimen revealed poorly differentiated adenocarcinoma limited to the main pancreatic duct. The tumor was unpedunculated, measuring 5 mm in diameter (Figs. 7, 8a and 8b). Mucosal lesions with atypia (Figs. 8 c and d) were also seen in several portions of the ducts unaffected by the carcinoma, suggesting multicentric cancer development.

　ERCP was indispensable for detecting this small carcinoma, and endoscopic pancreatic ductal biopsy was essential in differential diagnosis.