Fumarate hydratase–deficient renal cell carcinoma: an oncology care institutional experience

Renal cell carcinoma (RCC) accounts for 2% of all cancer cases worldwide, and majority are sporadic. The latest World Health Organization (WHO) classification of renal cell tumors (fifth edition, 2022) has molecularly defined renal tumor entities, which includes fumarate hydratase (FH)–deficient RCC. FH‐deficient RCC is an aggressive carcinoma caused by pathogenic alterations in FH gene, seen in 15% of patients with hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC) syndrome. These tumors occur more frequently at a younger age and present at an advanced stage, carrying a dismal prognosis. We report a series of 10 cases of FH‐deficient RCC. The mean age was 49.8 years, and all cases presented in advanced stages (III and IV). Morphologically, the cases had varied architectural patterns with characteristic eosinophilic macronucleoli and perinucleolar halo. On immunohistochemistry (IHC), all showed diffuse nucleo‐cytoplasmic expression of S‐(2‐succino)‐cysteine (2‐SC), with loss of FH in seven cases. FH‐deficient RCCs are aggressive neoplasms and can be diagnosed using specific IHC markers (FH and 2‐SC). These patients should undergo germline testing for FH gene mutation, genetic counseling, and surveillance of family members.