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Fumarate hydratase (FH)-deficient renal cell carcinoma (RCC) is a rare and distinct subtype of renal cancer caused by FH gene mutations. FH negativity and s-2-succinocysteine (2SC) positivity on immunohistochemistry can be used to screen for FH-deficient RCC, but their sensitivity and specificity are not perfect. The expression of AKR1B10, an aldo-keto reductase that catalyzes cofactor-dependent oxidation-reduction reactions, in RCC is unclear. We compared AKR1B10, 2SC, and FH as diagnostic biomarkers for FH-deficient RCC. We included genetically confirmed FH-deficient RCCs (n = 58), genetically confirmed TFE3 translocation RCCs (TFE3-tRCC) (n = 83), clear cell RCCs (n = 188), chromophobe RCCs (n = 128), and papillary RCCs (pRCC) (n = 97). AKR1B10, 2SC, and FH were informative diagnostic markers. AKR1B10 had 100% sensitivity and 91.4% specificity for FH-deficient RCC. The nonspecificity of AKR1B10 was shown in 26.5% of TFE3-tRCCs and 21.6% of pRCCs. 2SC showed 100% sensitivity and 88.9% specificity. However, nonspecificity for 2SC was evident in multiple RCCs, including pRCC, TFE3-tRCC, clear cell RCCs, and chromophobe RCCs. FH was 100% specific but 84.5% sensitive. AKR1B10 served as a highly sensitive and specific diagnostic biomarker. Our findings suggest the value of combining AKR1B10 and 2SC to screen for FH-deficient RCC. AKR1B10+/2SC+/FH- cases can be diagnosed as FH-deficient RCC. Patients with AKR1B10+/2SC+/FH+ are highly suspicious of FH-deficient RCC and should be referred for FH genetic tests.
Zheng et al. (Sat,) studied this question.