Light and electron microscopic observations on a congenital insulinoma

An insulinoma was found at the autopsy of a 48‐day‐old infant. The infant presented with documented hypoglycemia at 8 hours of age and the hypoglycemia continued throughout life despite medical therapy. The insulinoma was grossly a distinct nodule. Histologically, it was well‐defined and characteristic of an islet cell adenoma. The tumor cells contained granules that were positively stained with aldehyde fuchsin. With the electron microscope a heterogeneous granule cell population similar to those in the beta‐cell adenoma of the adult was seen.