ABSTRACT Hemangioblastoma (HB) is a benign central nervous system (CNS) tumor associated with mutations in the von Hippel–Lindau ( VHL ) gene. Although rare outside the CNS, the pathological and genetic features remain poorly understood. We analyzed four renal hemangioblastomas (RHB). Demographics, clinical presentation, and follow‐up data were collected. After assessing hematoxylin and eosin‐stained slides, immunophenotyping was conducted using CA9, α‐inhibin, AE1/AE3, CD10, CD56, PAX8, S100, MelanA, HMB45, CD117, FH, SDHB, and brachyury antibodies, alongside mismatch repair (MMR) deficiency examination. Additionally, whole‐exome sequencing (WES) was performed in 3 tumors. Our cohort comprised 3 male and 1 female patients, with a median age of 49 years. No data on VHL disease were available. Well‐circumscribed tumors (median size: 25.5 mm) displayed clear vacuolated cytoplasm with a vascular component. Immunostaining revealed expression of PAX8, α‐inhibin, AE1/AE3, S100, and cytoplasmic brachyury. WES analysis detected no pathogenic mutations. No cancer‐related deaths or progressions were observed. Histologically, RHB resembles low‐grade ccRCC and shares expression of PAX8, pancytokeratin, and CA9. However, RHB is uniquely positive for α‐inhibin, S100, and lacks VHL alterations. Its favorable prognosis underscores the importance of distinguishing it from ccRCC to prevent unnecessary treatments. Further research is warranted to elucidate the underlying genetic mechanisms.
Pósfai et al. (Thu,) studied this question.