SDHB and neoplasm: The ESMO guidelines, for their part, suggest using the definition of “high risk of metastasis” when one or more of the following criteria are present: (a) tumor size greater than or equal to 5 cm; (b) any extra-adrenal PPGL; (c) known germline SDHB pathogenic variant; or (d) plasma 3MT > 3 times above the upper limit of normal (26).