Succinate dehydrogenase-deficient renal cell carcinoma: A retrospective study, 1999–2018

Background: Succinate dehydrogenase-deficient (SDH-deficient) renal cell carcinoma (RCC) is a rare subtype of RCC. Approximately 0.05% – 0.2% of RCCs are SDH-deficient. It is usually associated with a pathogenic germline variant of the enzyme. Although the tumour is often indolent, it has a strong association with hereditary disease, most commonly paraganglioma and/or pheochromocytoma, and genetic testing is advised. Succinate dehydrogenase-deficient RCC is diagnosed by immunohistochemical (IHC) staining for SDH subunit B (SDHB), with loss of staining confirming SDHB deficiency. The incidence of SDH-deficient RCC in South Africa is unknown. Aim: To determine the incidence of SDH-deficient RCC in the Free State Province and its correlation with the worldwide incidence of 0.05% – 0.2%. Setting: Department of Anatomical Pathology, Universitas Academic Hospital and National Health Laboratory Service (NHLS) in Bloemfontein, South Africa. Methods: A retrospective descriptive study was performed. All primary RCCs diagnosed over a 20-year period (1999–2018) were included. An SDHB IHC stain was performed on all cases. A diagnosis of SDH-deficient RCC required loss of staining in all tumour cells in the presence of internal positive controls. Results: The study included 187 RCC cases. Two cases of SDH-deficient RCC were identified, representing an incidence of 1.1%. Both patients were male and were 22 and 44 years of age, respectively. Conclusion: The incidence of SDH-deficient RCC in central South Africa is slightly higher than global findings. Contribution: This study provides new data on SDH-deficient RCC in the South African context.