Succinate dehydrogenase (SDH) is a heterotetrameric nuclear encoded mitochondrial protein complex which plays a role in the citric acid cycle and the electron transfer chain. Germline mutations in SDHA are associated with Leigh syndrome. Mutations in SDHB, SDHC and SDHD are found in an increasing number of neoplasms, most notably paragangliomas and wild-type gastrointestinal stromal tumours. SDH deficiency in these tumours has important prognostic implications, and also provides a novel target for molecular therapy. In this article, we outline the structure and function of SDH and provide a summary of its role in various diseases.

Clear cell sarcoma of the kidney is an uncommon malignant pediatric renal neoplasm that typically presents in the 2- to 3-year age group and has a propensity for aggressive behavior and late relapses. Histologically, this tumor exhibits a great diversity of morphologic patterns that can mimic most other pediatric renal neoplasms, often leading to confusion and misdiagnosis. Until recently, adjunct immunohistochemical and molecular genetic tests to support the diagnosis were lacking. The presence of internal tandem duplications in BCL-6 coreceptor ( BCOR) and a translocation t(10;17) creating the fusion gene YWHAE-NUTM2B/E have now been well accepted. Immunohistochemistry for BCOR has also been shown to be a sensitive and specific marker for clear cell sarcoma of the kidney in the context of pediatric renal tumors. Improved intensive chemotherapy regimens have influenced the clinical course of the disease, with late relapses now being less frequent and the brain having overtaken bone as the most common site of relapse.