Late Onset Malignant Metastatic Transformation of Benign Pheochromocytoma.

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors arising from adrenal medulla and extra-adrenal paraganglia. Metastatic pheochromocytomas, pose diagnostic and therapeutic challenges due to their atypical presentations and potential for malignant transformation years after primary tumor resection. We report a case of 61-year-old woman who presented with intermittent cough, shortness of breath, and elevated blood pressure 6 years after resection of primary adrenal pheochromocytoma. Imaging revealed bilateral pulmonary nodules, a retroperitoneal mass, and L4 vertebral involvement, raising suspicion for metastatic pheochromocytoma. Elevated serum meta-nephrines and normetanephrines, alongside tissue biopsy and MIBG imaging, confirmed diagnosis. Germline genetic testing did not reveal any pathogenic mutations. The patient underwent CT-guided cryoablation for retroperitoneal lymph nodes and scheduled for radiofrequency ablation (RFA) of metastatic lesions. This case underscores evolving understanding of PPGLs, challenging "10 % rule" regarding metastasis and inheritance. While mutations in genes such as SDHB are associated with increased metastatic risk, sporadic cases like this highlight need for lifelong surveillance in all patients' post-resection of primary tumor. Ablative techniques, EBRT, and emerging systemic therapies are promising methods for managing metastatic disease. This case highlights importance of long-term follow-up and genetic testing in patients with PPGLs, even in absence of hereditary mutations, to detect and manage late-onset metastatic disease efficiently.