A Rare Case of Synchronous Fumarate Hydratase-Deficient Renal Cell Carcinoma and Clear Cell Renal Cell Carcinoma With Fumarate Hydratase and von Hippel-Lindau Gene Mutations: A Clinicopathologic and Molecular Study

Fumarate hydratase-deficient renal cell carcinoma (FH-deficient RCC) is a rare and aggressive tumor characterized by pathogenic alterations in the fumarate hydratase (FH) gene. Clear cell renal cell carcinoma (clear cell RCC) is a common renal cell carcinoma (RCC) associated with von Hippel-Lindau (VHL) gene variations. Here, we reported a case of bilateral RCCs. A 60-year-old man was admitted to hospital with a 3.6 cm x 3.3 cm mass in the right kidney and a 2.8 cm x 2.3 cm nodule in the left kidney. Pathologically, the right tumor showed a nested growth pattern of cells with clear cytoplasm and was FH positive and 2-succinylcysteine (2SC) negative. The left tumor demonstrated a high-grade papillary pattern and was FH negative and 2SC positive. Whole-exome sequencing and Sanger sequencing identified a germline FH c.563A > T mutation in both the tumors and an additional somatic VHL c.479_480insA mutation in the right tumor, confirming the diagnosis of clear cell RCC and FH-deficient RCC in the right and left kidneys, respectively. We reported a rare case of synchronous bilateral clear cell RCC (right) and FH-deficient RCC (left) likely driven by somatic VHL mutation and germline FH mutation, respectively.