alpha-chymotrypsin and Carcinoma--Acinar-Cell

Although pancreatic acinar metaplasia in the gastric mucosa is well recognized in chronic gastritis, gastric carcinoma with acinar differentiation is very rare. We encountered a case of gastric adenocarcinoma with prominent histologic and immunohistochemical features of pancreatic acinar differentiation in the absence of identifiable heterotopic pancreatic tissue. Distinct glandular and diffuse patterns of adenocarcinoma were also present, and there was focal mucin production. The tumor strongly expressed pancreatic exocrine enzymes trypsin and chymotrypsin, and focal neuroendocrine staining was also present. To investigate the prevalence of acinar differentiation in histologically typical gastric cancers, we performed immunohistochemical staining for trypsin and chymotrypsin on a tissue microarray containing 111 conventional gastric adenocarcinomas (60 intestinal, 28 mixed, 22 diffuse type, and 1 undifferentiated). No obvious morphologic evidence of acinar differentiation was identified in any of the 111 cases. Although some cases showed equivocal staining for at least 1 pancreatic exocrine enzyme on the initial tissue microarray sections, repeat immunohistochemical staining on representative whole-tissue sections failed to reproduce positive staining. Thus, acinar differentiation is rare in gastric adenocarcinomas, other than in histologically unusual cases such as the one we report, and in others from the literature, which are reviewed.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Biopsy; Carcinoma, Acinar Cell; Cell Differentiation; Chymotrypsin; Female; Gastrectomy; Humans; Immunohistochemistry; Male; Metaplasia; Middle Aged; Stomach Neoplasms; Tissue Array Analysis; Trypsin

Acinar cell carcinomas of the pancreas are rare neoplasms. Usually diagnosed at an advanced stage, in general they are large solid pancreatic tumours with an average size of more than 10 cm.. We report 3 cases of acinar cell carcinomas involving the peripancreatic lymph nodes, the liver hilum and the colon respectively, without clinical or pathological evidence of pancreatic tumours. These highly cellular neoplasms showed a predominantly acinar cell differentiation intermingled with a ductal component, with intracellular or extracellular mucin production by at least 25% of tumour cells. In addition, one case showed endocrine differentiation. Diffuse immunoreactivity for acinar enzymes trypsin and chymotrypsin was present in all cases.. The occurrence of acinar cell carcinomas outside the pancreas underlines the notion that acinar cell carcinomas may originate in extrapancreatic sites and probably develop from heterotopic or metaplastic pancreatic foci present along the biliary tract.

Topics: Aged; Carcinoma, Acinar Cell; Chymotrypsin; Humans; Immunohistochemistry; Liver Neoplasms; Lymphatic Metastasis; Male; Middle Aged; Pancreatic Neoplasms; Retroperitoneal Neoplasms; Trypsin

Histologic differential diagnosis of acinar cell carcinoma (ACC), mixed acinar-endocrine cell carcinoma (MAEC), and pancreatic endocrine tumors (PET) can be difficult but is important because of differences in their clinical behavior. This study investigates the utility of immunohistochemistry (IHC) in this differential diagnosis using immunohistochemical stains that are available in most laboratories. IHC was performed on paraffin-embedded tissue in ACC (n = 6), MAEC (n = 2), and PET (n = 13), using synaptophysin (SYN), chromogranin (CHR), chymotrypsin (CHY), and alpha-1-antitrypsin (AAT). Electron microscopy (EM) was performed in all cases to confirm the diagnosis. Long-term follow-up and death of disease (DOD) was known in all patients. The ACCs stained as follows: CHY (4/6), AAT (3/6), SYN (4/6); CHR was negative in all cases. Both cases of MAEC stained with CHY, AAT, and SYN (2/2); CHR was negative. PET stained as follows: SYN (13/13), CHR (8/13), CHY (4/13), AAT (5/13). In the ACC/ MAEC group, six of eight patients were DOD at mean follow-up of 11 months. Among the PET, two of 16 patients were DOD at mean follow-up of 37 months. Considerable immunophenotypic overlap exists between ACC, MAEC, and PET. Consequently, one can neither confirm nor rule out a diagnosis of ACC or MAEC using generally available immunohistochemical stains alone. These findings support a role for EM in the evaluation of exocrine and endocrine pancreatic neoplasms.

Topics: Adult; Aged; Aged, 80 and over; alpha 1-Antitrypsin; Carcinoma, Acinar Cell; Chromogranins; Chymotrypsin; Diagnosis, Differential; Endocrine Gland Neoplasms; Female; Follow-Up Studies; Humans; Immunohistochemistry; Male; Microscopy, Electron; Middle Aged; Pancreatic Neoplasms; Synaptophysin; Time Factors