Abstract

Histochemical, light and electron microscopic studies of an insulin secreting islet cell carcinoma are presented. A 28-year-old female patient complained of a loss of consciousness, especially at the fasting time, with hypoglycemia below 45 ㎎%. The symptom was relieved after meals. Celiac angiography revealed abnormal proliferation of tumor vessels between the body and tail portion of the pancreas. An operation was performed under he diagnosis of functioning B cell tumor of the pancreatic islet. A histological examination of hematoxylin-eosin stained sections of the surgical specimen revealed gyriform pattern or diffuse growth pattern of the tumor cells with vascular and perineural invasion. Histochemical studies including aldehyde fuchsin, phosphotungstic acid hamatoxylin stain and modified Scott's stain revealed positive reaction with the reagents that recognized normal B cells of the Langerhans islet. An electron microscopic study revealed that this tumor consisted mainly of cells with a few, immature beta granules. Numerous dense granules resembling lysosomes were found in the majority of the cells. Extensive interdigitations of the cell membrane formed the intercellular spaces. She is relatively well without hypoglycemia for 1 year after the operation.