NF1 and multiple endocrine neoplasia type 2: Although a sporadic form exists, the vast majority of PPGLs occur as a manifestation of inherited tumour syndromes such as multiple endocrine neoplasia type 2 (MEN2; RET gene), von Hippel–Lindau (VHL) disease (VHL gene), neurofibromatosis type 1 (NF1; NF1 gene), and hereditary PPGL [3,4,5,6].