SDHB and renal cell carcinoma: Based on the expansion of the 2016 WHO New Classification of Male Urologic Renal Tumors, a total of 15 cases of pure low-grade FH-deficient RCC were screened in retrospective studies and routine differential diagnosis by many scholars in recent years, and some of them were previously classified as other renal tumors, such as unclassified renal cell carcinoma (7) or oncocytoma (8), which were initially reported and described as resembling “SDH-deficient RCC morphology” (6) by Smith et al.