A Novel Mutation (P236S) in the Succinate Dehydrogenase Subunit B Gene in a Japanese Patient with a Posterior Mediastinal Paraganglioma

Succinate dehydrogenase subunit B gene (SDHB) is associated with the development of hereditary paraganglioma (PGL) and pheochromocytoma (PCC). Here we describe a novel germline mutation in SDHB in a 69-year-old Japanese woman with a posterior mediastinal PGL. We summarize the clinical presentation, diagnostic work-up, and pathological features of a patient with a posterior mediastinal PGL and review the pertinent literature. Direct sequencing of SDHB and SDHD was performed. The patient presented with a posterior mediastinal tumor and was normotensive. She underwent abdominal tumor resection at the age of 38 years, but clinical and pathological diagnoses were unknown. She had no family history of hypertension, PGL, or PCC. Imaging studies suggested that the tumor was neurogenic. Endocrinological examinations showed normal plasma catecholamine levels. The tumor was completely removed without metastasis. Pathological findings confirmed PGL. Immunohistochemical staining showed that the tumor cells were positive for chromogranin A, synaptophysin, and CD56, and the Ki67 index was low (< 1 %). The patient has not experienced recurrence or metastasis for the last 5 years. DNA sequencing revealed a novel P236S (c.843 C > T) mutation in SDHB. The P236S germline mutation in SDHB was associated with posterior mediastinal PGL. Strict follow-up of the patient is necessary because the SDHB mutation may be related to malignancy.