Genetic abnormalities (aryl hydrocarbon receptor-interacting protein (AIP) gene, ubiquitin specific protease 8 (USP8) gene mutation) have been reported to be related to tumor development and proliferation in a proportion of functioning PAs (acromegaly, Cushing’s disease) [10], but the mechanism of pathogenesis and growth in most PAs is unclear. This evidence concerns the gene USP8 and neoplasm.