Multiple ectopic lesions of focal islet adenomatosis identified by positron emission tomography scan in an infant with congenital hyperinsulinism

Congenital hyperinsulinism (HI) exists in 2 histologic forms, focal and diffuse, and rarely has been attributed to lesions in ectopic pancreatic tissue. The ability to distinguish focal from diffuse HI and locate focal lesions has been difficult, thus limiting the optimal management of HI. We present a case of HI resulting from focal pancreatic and ectopic pancreatic lesions. After a near-total pancreatectomy failed to improve the patient's condition, a positron emission tomography (PET) scan performed with ¹⁸F-fluoro-l-dihydroxyphenylalanine demonstrated a focal lesion remaining in the head of the pancreas as well as 4 hot spots inferior to the remaining pancreas. Surgical exploration found pancreatic rests in the jejunum responsible for the hot spots seen on PET. Resection of the remainder of the pancreas as well as the small intestinal lesions resulted in correction of the patient's HI. Pathology confirmed the presence of focal HI lesions in the pancreatic head and small intestinal specimens. This case supports the ability of ectopic pancreatic tissue to contribute to the pathology of HI. It highlights the ability of PET to successfully identify focal lesions, including ectopic tissue, responsible for hyperinsulinemic hypoglycemia.