Glucagonoma is a rare, functioning type of pancreatic neuroendocrine tumor (PNET; see this term) that hypersecretes glucagon, leading to a syndrome comprised of necrolytic migratory erythema, diabetes mellitus, anemia, weight loss, mucosal abnormalities, thromboembolism, gastrointestinal and neuropsychiatric symptoms.

Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy.