A rare entity of malignant insulinoma diagnosed after 30 years of clinical manifestation of hypoglycemia: A case report and literature review

Malignant insulinomas, a rare life threatening pathology, exists in literature as an entity that constitutes 10% of all insulinomas and often present as multi-centric macro nodules with multiple lymph nodes or liver metastases before diagnosis. We report a rather rare case of a 68 year old male with a 30 years history of uninvestigated severe hypoglycemic attacks that improved on glucose intake. Blood tests showed a decreased value of glycemia (45 mg/dL) associated with increased insulin level (54 μU/ml) and an increased glycemia/ insulinemia ratio of 0.83 supporting the diagnosis of insulinoma. Abdominal CT showed a 4 cm mass localized in the head of the pancreas with atrophic body and tail, no signs of distant metastatic disease. A concomitant diagnosis of primary hyperparathyroidism raised, based on elevation of calcium associated and high level of PTH. The coexistence of the two endocrinopathies suggested the presence of type 1 multiple endocrine neoplasia (MEN I). Based on the workup suggesting a benign insulinoma with no signs of metastatic disease, co-existing with debilitating symptoms of hypoglycemia, pancreatectomy with lymph node dissection was performed. Histo-pathological examination returned surprisingly positive for malignant neuro-endocrine tumor with positive lymph nodes. In that domain, we summarized the literature discussion of neuroendocrine tumors, elaborating on malignant insulinoma diagnosis and management. Furthermore, what our article is trying to lay upon existing literature is a case of a long standing existent MEN 1 malignant insulinoma manifesting as a remarkably slow progressive disease of 30 years' timeline versus a less likely chance of a transformation from benign insulinoma to malignant.