A Somatic HIF2 alpha Mutation-Induced Multiple and Recurrent Pheochromocytoma/Paraganglioma with Polycythemia: Clinical Study with Literature Review

摘要

A syndrome known as pheochromocytomas (PCC)/paragangliomas (PGL) and polycythemia resulted from gain-of-function mutation of hypoxia-inducible factor 2 alpha (HIF2 alpha) has been reported recently. However, clinical features of this syndrome vary from patient to patient. In our study, we described the clinical features of the patient within 15-year follow-up with a literature review. The patient presented with "red face" since childhood and was diagnosed with polycythemia and pheochromocytoma in 2000, and then, tumor was removed at his age of 27 (year 2000). However, 13 years later (2013), he was diagnosed with multiple paragangliomas. Moreover, 2 years later (2015), another two paragangaliomas were also confirmed. Genetic analysis of hereditary PCC/PGL-related genes was conducted. A somatic heterozygous missense mutation of HIF2 alpha (c.1589C > T) was identified at exon 12, which is responsible for the elevated levels of HIF2 alpha and erythropoietin (EPO) and subsequent development of paragangaliomas. However, this mutation was only found in the tumors from three different areas, not in the blood. So far, 13 cases of PCC/PGL with polycythemia have been reported. Among them, somatic mutations of HIF2 alpha at exon 12 are responsible for 12 cases, and only 1 case was caused by germline mutation of HIF2 alpha at exon 9. The HIF2 alpha mutation-induced polycythemia with PCC/PGL is a rare syndrome with no treatment for cure. Comprehensive therapies for this disease include removal of the tumors and intermittent phlebotomies; administration of medications to control blood pressure and to prevent complications or death resulted from high concentration of red blood cell (RBC). Genetic test is strongly recommended for patients with early onset of polycythemia and multiple/recurrent PCC/PGL.