Renal cell carcinoma with atypical omental metastasis: A case report and literature review

Abstract Background Renal cell carcinoma (RCC) is the most common type of kidney cancer in adults, with common metastatic sites including the lungs, bones, liver, and brain. Omental metastasis is exceedingly rare and usually occurs postoperatively. Fumarate hydratase‐deficient (FH‐deficient) RCC, a recently classified and highly aggressive subtype of RCC, is known to show early metastatic potential but remains poorly understood. We present a rare case of synchronous FH‐deficient RCC with isolated omental metastasis identified at diagnosis. Case Presentation We report the case of a 48‐year‐old man who first presented with abdominal pain, early satiety, and a 25‐pound weight loss. Imaging revealed an 11.8 cm right renal mass with a separate 15.4 cm left upper quadrant mesenteric mass with no definitive evidence of lung, bone, or liver involvement. Biopsies of both renal and mesenteric masses confirmed non‐clear‐cell FH‐deficient RCC with papillary architecture and diffuse overexpression of 2‐succinyl cysteine. Conclusion Omental metastasis of RCC is rare, especially in the absence of prior surgery. This case is distinguished by its synchronous presentation of the primary RCC and omental metastasis with a rare histologic subtype. Unlike most documented reports of RCC with omental spread, which typically involve clear cell histology and often present years after nephrectomy, this case involves a rare, aggressive subtype with atypical metastatic behavior. This case underscores the importance of considering atypical metastatic patterns in non‐clear‐cell subtypes and the need for further research to inform evidence‐based therapy.