An endocrine active insulinoma with extended lymphogenic dissemination

Insulinomas are often solitary endocrine tumors and are metabolic active in 80% to 90% of cases. In 5% to 15% of cases they are malignant but rarely metastasize. When an insulinoma is diagnosed, appropriate imaging is recommended and must especially focus on the liver, because the presence of liver metastases is the most important prognostic factor of malignant insulinomas. Computed tomographic (CT) scans and somatostatin receptor scintigraphy (SRS) are used to define the extent of the primary tumor and to determine treatment options with lutetium(177Lu)-labeled octreotide. 177Lu decays by emission of β-particles with Emax of 497 keV (78.6%), 384 keV (9.1%), and 176 keV (12.2%) with a half-life of 6.71 d. It also emits γphotons of 113 keV (6.4%) and 208 keV (11%), which are well suited for imaging. The β-particles have a range of 3-4 mm. With these properties it is suitable for therapy. In the case presented here, a 33-year-old man with a malignant insulinoma with extensive lymph node metastases is described, and the findings of CT scanning and SRS scintigraphy are shown. Histopathologic examination confirmed the diagnosis.