Succinate dehydrogenase B (SDHB) protein is an integral part of the complex II oxidation/reduction pathway. Its function is to transfer electrons from succinate to coenzyme Q.SDHB can be used to differentiate between type 1 (SDHB +) and type 2 (SDHB -) gastrointestinal stromal tumors (GIST).SDHB immunohistochemistry has emerged as a reliable method for diagnosing and screening of SDH-deficient tumors, including SDH-deficient pheochromocytoma/paraganglioma, SDH-deficient GIST, and SDH-deficient renal cell carcinoma.