Early-Onset Sarcoma With Germline MAX Variant: Expanding the Spectrum in Hereditary Pheochromocytoma and Paraganglioma.

Germline pathogenic variants in MYC-associated factor X () are a rare cause of hereditary pheochromocytoma and paraganglioma (PPGL) syndrome, typically presenting with pheochromocytomas (PCC). Although -related PPGLs are generally characterized by an adrenergic phenotype and bilateral tumors in 67% of cases, the tumor spectrum associated with pathogenic variants remains poorly understood. We present a case of a 28-year-old man with a germline pathogenic variant (c.64-2A>G) who developed bilateral PCC and later, a liver sarcoma with a variant and gene fusion. The diagnosis of sarcoma in this young patient underscores a potential association between pathogenic variants and an increased predisposition to sarcoma development. Our findings suggest that -related PPGLs may be associated with other malignancies, including sarcoma, and support expanding surveillance guidelines to include whole-body imaging for early detection of extra-adrenal tumors. Given the rarity of pathogenic variants, further studies are needed to elucidate the full spectrum of presentation and establish comprehensive evidence-based surveillance strategies.