Pancreatic Neuroendocrine Neoplasm Associated with a Familial MAX Deletion.

Most pancreatic neuroendocrine neoplasms (pNEN) occur sporadically but they can also occur as part of multiple endocrine neoplasia type 1 (MEN1). MAX was originally described as an inherited pheochromocytoma-paraganglioma risk gene, but also has recently been implicated in pituitary tumorigenesis. Here we describe the first case of a pNEN associated with an inherited MAX gene deletion in a family with endocrine tumors. The patient was a male carrier of an intragenic exon 3 deletion inherited from his father who had recurrent pheochromocytomas and a macroprolactinoma. The patient underwent screening and hormonal studies but no pheochromocytoma-paraganglioma, pituitary or renal tumors were identified. However, abdominal magnetic resonance imaging (MRI) identified a 1 cm lesion in body of the pancreas. The lesion was hyperintense on T2-weighted signal, and there was hyperfixation of the tumor on 68Ga-DOTANOC PET-CT images. No biochemical evidence of pancreatic hormone excess was identified. Following a guided biopsy, a pathological diagnosis of a low grade pNEN was made and immunohistochemistry showed loss of MAX nuclear staining. Genetic analysis of the tumor tissue indicated copy number neutral loss of heterozygosity consistent with uniparental disomy. This is the first reported case of a MAX deletion associated pNEN and strengthens the argument that MAX may represent an inheritable multiple endocrine neoplasia risk gene. Further analysis of germline and somatic MAX mutations/deletions in large cohorts of unexplained NEN cases could help clarify the potential role of MAX in NEN etiology.