Beckwith-Wiedemann syndrome: a quantitative, immunohistochemical study of pancreatic islet cell populations.

The endocrine cell content of the pancreas of two cases of Beckwith-Wiedemann syndrome with islet cell adenomatosis were studied. Insulin, glucagon, somatostatin and pancreatic polypeptide cells were evaluated qualitatively and quantitatively with the indirect immunofluorescence method and morphometry was used to establish the volume density of the four endocrine cell populations. This evaluation showed a marked increase of insulin and glucagon cells and a lesser augmentation of pancreatic polypeptide cells and somatostatin cells. However, the percent of somatostatin cells was decreased in comparison with controls. Qualitatively, the two pancreas were characterized by the lack of segregation of glucagon and pancreatic polypeptide cells to distinct parts of the gland, with each cell type being abundant in the pancreatic region in which they are normally very sparse. The marked increase of endocrine cells often took the form of giant islet-like structures formed by smaller subunits; however, despite this increase, the distribution of insulin cells respected the normal pattern, i.e. clusters of B cells surrounded by non-B cells. These findings indicate that besides the proliferation of pancreatic endocrine cells maintaining a normal topographical distribution of B versus non-B cells, the pancreas of patients with the Beckwith-Wiedemann syndrome may have undergone abnormal development with a consequent lack of segregation of glucagon and pancreatic polypeptide cells to different parts of the gland.