Metastatic sympathetic paraganglioma in a patient with loss of the SDHC gene.

Mutation of the genes encoding the succinate dehydrogenase (SDH) subunits A, B, C, or D, or the SDHAF2 protein, cause the SDHx-hereditary paraganglioma syndromes. Hereditary susceptibility to metastatic sympathetic pheochromocytomas and paragangliomas is most commonly due to germline mutations in the SDHB gene. Individuals with SDHD mutations occasionally present with metastatic disease, while conversely malignant paragangliomas are rarely observed in SDHC carriers. A 43 year-old woman presented with an abdominal paraganglioma metastatic to the skeleton and multiple lymph nodes. The tumor produced excessive amounts of noradrenaline causing hypertension and symptoms of catecholamine excess. The patient underwent surgical resection of the primary tumor and lymph node metastases. Loss of SDHB protein expression in the primary tumor was demonstrated by immunohistochemistry. Germline sequencing and deletion testing revealed a large allelic deletion of exons 1-6 in SDHC, and no mutations or deletions were detected in SDHB or SDHD. The patient's mother died because of kidney cancer. Hereditary pheochromocytomas and paragangliomas may be associated with a deletion of the SDHC gene. These patients may present with malignant sympathetic paragangliomas.