p53 and proliferating cell nuclear antigen in endocrine tumors of pancreas and intestinal carcinoids.

Twenty six endocrine tumors of the pancreas and 19 carcinoids of the intestinal tract were studied with immunocytochemical staining for p53 and proliferating cell nuclear antigen (PCNA) to detect any correlation between PCNA and p53 immunostaining. PCNA immunostaining is somewhat variable in endocrine tumors of the pancreas whereas p53 overexpression was detected in one out of eight insulinomas (12.5%), four out of eight gastrinomas (50%) and none of two glucagonomas, six PPomas and two non-functioning tumors. In 19 intestinal carcinoids, two of eight small-intestinal carcinoids (25%) were positive for p53 whereas five appendiceal and two colonic carcinoids were negative for p53. It was concluded that: 1. PCNA staining is variable with no clear distinction between benign and malignant endocrine tumors of the pancreas and intestinal carcinoids, although positive PCNA staining may assess growth fraction of tumors; 2. p53 overexpression is relatively rare both in endocrine tumors of the pancreas (one out of 18 non-gastrinomas) and intestinal carcinoids, except for gastrinomas, in which 50% were positive for p53; and 3. non-neoplastic islet cells are positive for p53.