The Characteristics and outcomes of patients with malignant pheochromocytoma and paraganglioma: Single-Center Experience

Introduction: Metastatic pheochromocytoma (PCC) and paraganglioma (PGL) [PPGL] are rare neuroendocrine malignancies characterized by the presence of metastasis in nonchromaffin tissue. However, the data for clinical, histological, or biochemical predictors of metastatic behavior is scarce. So, we aimed to present the clinical features, treatment, and outcomes of our PPGL patients with metastatic behavior. Methods: A total of 38 patients with the diagnosis of PPGLs (n=35 PCCs and n=3 PGLs) were enrolled in the study between 2010 and 2019. The demographics, clinical features, laboratory tests, radiological data, treatments, and outcomes of the patients were analyzed. Results: The mean age was 38.3±15.3 years, and the female to male ratio was 22/16. Underlying etiology was hereditary in 60% of PCCs [multiple endocrine neoplasia (MEN) type 2A in 17 patients; MEN type 2B in 4 patients; and neurofibromatosis in one patient]. The metastatic disease was observed in 5 patients with PPGLs (n=4 of PCCs and n=1 of PGLs). The metastatic cases were sporadic all PPGL patients. The mean maximum size of the primary tumor of metastatic PPGL cases was 4.5±3.2 cm. The sites of metastasis for PCCs were liver, bones, lungs, and lymph nodes in all cases. All metastatic patients underwent surgery. Cytotoxic chemotherapy and 131I- metaiodobenzylguanidine (MIBG) radionuclide therapy were given for all PCCs and external beam radiation for PGL patients. Three of the cases were stable with cytotoxic chemotherapy and 131I-MIBG, but one case exacerbated and died after a total of four cycles of 177Lu therapy. Discussion: In our tertiary referral center, the majority of the patients who were followed with PPGLs have hereditary/genetic etiology. ~10% of our PPGL patients showed malignant features, which was consistent with the literature. Additionally, these patients should be managed in referral centers with a multidisciplinary approach providing chemotherapy and theranostic therapies.