Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) is a rare subtype of renal neoplasm predominantly affecting younger individuals. It is characterized by germline mutations in SDHx genes, particularly type B. Histologically, SDH-deficient RCC features eosinophilic cytoplasmic cells forming solid nests or microcysts, sometimes entrapping normal tubules. We present three SDH-deficient RCC cases with overlapping morphological features with fumarate hydratase-deficient RCC and TFEB-rearranged RCC, an appearance that has not been previously described. All tumors lacked SDHB expression and harbored pathogenic SDHB mutations, with the germline nature confirmed in two cases. Metastasis developed in two patients. Our case set highlights the diagnostic challenges of molecularly defined renal tumors and expands the morphological spectrum of SDH-deficient RCC with unusual histological features. Clinically, these tumors appear to be aggressive.

• Keywords
• RCC, Renal cell carcinoma, SDHB, Succinate dehydrogenase,
• MeSH
• Cell Dedifferentiation MeSH
• Adult MeSH
• Fumarate Hydratase deficiency   genetics   MeSH
• Carcinoma, Renal Cell * genetics   pathology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Biomarkers, Tumor genetics   analysis   MeSH
• Kidney Neoplasms * pathology   genetics   MeSH
• Aged MeSH
• Succinate Dehydrogenase * deficiency   genetics   MeSH
• Basic Helix-Loop-Helix Leucine Zipper Transcription Factors genetics   MeSH
• Germ-Line Mutation MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Publication type
• Journal Article MeSH
• Case Reports MeSH
• Names of Substances
• Fumarate Hydratase MeSH
• Biomarkers, Tumor MeSH
• SDHB protein, human MeSH Browser
• Succinate Dehydrogenase * MeSH
• TFEB protein, human MeSH Browser
• Basic Helix-Loop-Helix Leucine Zipper Transcription Factors MeSH