2023 Volume 38 Issue 1 Pages 51-59
To clarify the histological features and utility of immunostaining, 83 autopsy cases, 15 cases of obstructive pancreatitis, and eight cases of tumefactive chronic pancreatitis were analyzed histologically and immunohistochemically for CD56 and cytokeratin 19 (CK19). Acinar ductal metaplasia (ADM) was identified in 50 autopsy cases (60%), all cases (100%) of obstructive pancreatitis, and seven cases (88%) of chronic pancreatitis. In lesions with ADM, the typical purple color in the normal pancreatic tissue was diminished, and microcystic structures that looked like dilated acinar lumens (notable in the autopsy cases) and small duct-like structures (notable in the cases of obstructive pancreatitis) were observed. ADM in the autopsy cases contained protein plugs, and degree of ADM formation correlated with fat necrosis (P < 0.001) or inflammatory cell infiltration (P = 0.002), indicating that ADM is a reflection of acinar cell injury. ADM was diffusely positive for CD56. CD56 expression in ADM was more specific than CK19, which was also expressed in the intercalated ducts and centroacinar cells, and is a useful immunohistochemical marker.
