A highly malignant succinate dehydrogenase-deficient renal cell carcinoma with bone metastasis misdiagnosed as hereditary leiomyomatosis and renal cell carcinoma-a case report and literature review

Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) is an autosomal dominant syndrome caused by heterozygous pathogenic germline variants of the SDH gene. It is associated with an increased risk of developing RCC. To date, only a few publications have described the disease, and the clinical, morphological, and molecular aspects need to be further studied. The present study reported a case of SDH-deficient RCC with high malignancy and rare bone metastasis. In addition, the patient's postoperative pathological diagnosis was uncertain, and hereditary leiomyomatosis and RCC were highly suspected. The patient was diagnosed with a right renal mass through B-ultrasound examination and was found to have carcinoma embolus in the right renal vein and inferior vena cava through kidney contrast-enhanced computed tomography. A whole-body bone scan revealed radionuclide accumulation in the upper end of the left humerus, indicating possible pathological bone destruction. As a result, surgical resection was performed. The postoperative pathology indicated a high-grade RCC, although the specific classification remained uncertain, with a strong suspicion of hereditary leiomyomatosis and RCC. Subsequently, the germline mutation of the SDH complex flavoprotein subunit A (SDHA) gene was identified through high-throughput sequencing (c.1A>G, p. Met1?) and immunohistochemistry (IHC) revealed the loss of SDHB expression. Post-operatively, the patient underwent radiotherapy and targeted therapy. After a 6-month follow-up period, there was no indication of recurrence or metastasis on imaging. Based on this report, germline screening should be encouraged in early-onset patients. Family history or pathological results may not provide accurate information for the diagnosis and differential diagnosis of SDH-deficient RCC in advance.