DIAGNOSIS of ENDOCRINE DISEASE: SDHx mutations: beyond pheochromocytomas and paragangliomas.

Mutations in one of the five genes encoding the succinate dehydrogenase (SDHx) or mitochondrial complex II cause the corresponding family syndromes characterized by the occurrence of pheochromocytomas (PHEO) and paragangliomas (PGL). Recently, other solid growths, such as gastrointestinal stromal tumors (GISTs), renal cell carcinomas (RCCs) and pituitary adenomas (PAs) have been associated with these syndromes. In the absence of prospective studies assessing their frequency, at present, their occurrence seems too infrequent to suggest systematic screening for SDHx mutation carriers. However, SDHB immunohistochemistry (IHC) on tumor tissues or SDHx genetic testing on blood or tumor samples should be performed in patients affected by GISTs, RCCs or PAs with clinicopathologic phenotypes suggesting an etiologic role of SDHx genes.