慢性膵炎のERCP診断の位置づけ

A Critical Evaluation of ERCP in the Diagnosis of Chronic Pancreatitis

　内視鏡的膵胆管造影（ERCP）が本邦で実用化されてから，膵疾患の診断に重要な役割を果たすようになった．従来，診断が困難であった膵疾患がERCPで膵管を造影することによって，その存在診断だけでなく質的診断まである程度できるようになった．膵管像と組織像の対比も行われ^1)～4)，各種膵疾患の膵管像の分類についても報告がある⁵⁾⁶⁾．しかし，膵管像は膵実質の変化を常に忠実に反映するとは限らず，両者の変化に不一致があることは当然で，ERCPの所見だけから膵疾患の正確な診断を行うことは困難な場合がある．膵癌や慢性膵炎に典型的な変化がERCPでみられれば診断は簡単であるが，膵癌と慢性膵炎は類似した変化が膵管造影像にみられることがあるし，膵管の閉塞がある例ではその疾患の診断が困難であることが多い⁷⁾⁸⁾．

　今回は膵管造影像に異常がみられた例をとりあげ，これらの例を臨床的にどのようにとり扱うべきか考察し，慢性膵炎の形態学的診断について検討した．

　Between 1972 and 1977, 1269 cases were examined by ERCP. In 121 abnormal pancreatogram, i.e., occlusion, stenosis, irregularity or dilatation of the pancreatic duct was found. 121 cases included 54 pancreatic carcinomas and 67 other pancreatic lesions. All of pancreatic carcinomas were preoperatively diagnosed by ERCP and angiography and were excluded from present study. 67 abnormal pancreatograms other than pancreatic carcinoma were difficult to assess the nature of pancreatic disease and angiography was performed to make definitive diagnosis. Abnormal pancreatogram was classified into 6 groups (Table 1). Accuracy of angiographic diagnosis in abnormal pancreatogram is listed in Table 2. The results indicate that angiography is effective for excluding pancreatic carcinoma in patient with abnormal pancreatogram. Pancreatic cyst is easily diagnosed by ERCP and angiography. The most difficult lesion to diagnose is chronic pancreatitis. Six patients with clinical diagnosis of chronic pancreatitis underwent operation and resected specimen was histologically examined. One out of 85 postmortem pancreatogram showing typical changes of pancreatitis was added to histologic study (Table 3). Histologic definition of chronic pancreatitis is diffuse fibrosis with round cell infiltration and marked disorganized acinal cells. Only 3 out of 6 resected specimens showed typical histologic findings of chronic pancreatitis (Fig. 1) and in remaining 3 there were no findings suggestive of chronic pancreatitis in spite of typical changes indicating pancreatitis in ERCP and angiography (Fig. 2). Also postmortem pancreatogram showed marked changes, however, there were no histologic findings of chronic pancreatitis (Fig. 3). The spectrum of ERCP findings indicating only advanced, severe chronic pancreatitis can be diagnosed by pancreatogram. In those cases pancreatic carcinoma must be excluded preoperatively by other modalities, especially by angiography, since pancreatogram shows similar changes both in carcinoma and advanced pancreatitis.