Based on these findings, it could be inferred that 123I-MIBG scintigraphy was not the optimal study for localizing tumor sites; further, since most of the SDHA-related metastatic PHEO/PGLs lacked avidity or detected few lesions on 123I-MIBG scintigraphy, it could not be included as a therapeutic option in this group of patients (33), which is similar to SDHB-related metastatic PHEOs/PGLs and points toward an unfavorable prognosis (45). The gene discussed is SDHB; the disease is neoplasm.