<unk> s are derived from neural tissue, as can be demonstrated by immunohistochemistry and ultrastructural evidence using electron microscopy. These lesions characteristically consist of polygonal cells with bland nuclei, abundant cytoplasm and fine eosinophilic cytoplasmic granules. The<unk>  cells stain positively for S-100 as they are of Schwann cell origin. Both malignant and benign versions of the<unk>  exist, where malignant<unk> s are characterized histologically by features such as spindling, high nuclear to cytoplasmic ratios, pleomorphism, and necrosis. Multiple<unk> s may seen in the context of LEOPARD syndrome, due to a mutation in the PTPN11 gene. These<unk> s, on occasion, may appear similar to neoplasms of renal (relating to the kidneys) origin or other soft tissue neoplasms.
Granular cell tumor
Glomus tumor
Glucagonoma
Insulinoma
Hürthle cell adenoma
Metastatic insulinoma
Hibernoma
Metanephric adenoma