Current Knowledge and Prospects for Renal Hemangioblastoma and Renal Cell Carcinoma with Hemangioblastoma-like Features

Primary intrarenal hemangioma - A series of 39 cases

Intrarenal hemangiomas lack concise clinicopathologic information, due to the predominance of single case reports and inclusion of other vascular neoplasms and hemangiomas of perirenal, hilar, and renal vein origin. Herein, in this multi-institutional study we evaluate clinicopathologic features of 39 intrarenal hemangiomas. The median age was 62 years (range = 27-94 years; 2:1 male to female ratio), with left-sided predominance (left = 21, right = 13; one case was bilateral). The median tumor size was 1.5 cm (0.2-10 cm). Two cases arose from transplanted kidneys. Most were asymptomatic (n = 30, 86 %), even though most surgical interventions (19 partial, 19 radical, 1 biopsy) were due to hemangiomas (n = 24, 62 %). Synchronous renal neoplasms were present in 9 (23 %) patients, including clear cell renal cell carcinoma (RCC) (n = 4), angiomyolipoma (n = 2), oncocytoma (n = 2), and chromophobe RCC (n = 1). Multifocal hemangiomas (n = 5) were seen in cases with end stage renal disease. Intrarenal hemangiomas were mostly anastomosing (n = 18; 46 %), followed by capillary (n = 15; 38 %), and cavernous (n = 6; 16 %) subtypes. Fibrin thrombus (n = 9; 23 %) and extramedullary hematopoiesis (n = 4; 10 %) were occasionally present, the latter being only in the anastomosing subtype. Immunohistochemistry was performed on a majority (n = 33, 84 %) of hemangiomas, with vascular markers CD31 and CD34 and lack of PAX8 were most used for diagnosis. 30 patients had follow-up (median 48 months, range 1-241 months), none showed disease progression/recurrence. This study provides comprehensive observation of the largest intrarenal hemangioma cohort, highlighting their frequent cause of surgical intervention when present, predominance of anastomosing subtype, multifocality in end stage kidney disease, and occasional concurrent ipsilateral neoplasms.

Clinicopathological features and molecular genetic changes of primary renal hemangioblastoma, a TSC-associated tumor

BACKGROUND

Renal hemangioblastoma (HB) is a rare extra-central nervous system (CNS) tumor, typically not linked to Von Hippel-Lindau (VHL) Syndrome, and its underlying genetic drivers and molecular mechanisms remain elusive. The objective of this study is to investigate the clinicopathological features and molecular genetic changes of primary renal hemangioblastomas.

METHODS

Herein, the clinical, imaging, clinicopathological features, and immunophenotype in 3 cases of renal HB were retrospectively analyzed. Next generation sequencing (NGS) was employed to detect 116 gene loci, including VHL gene.

RESULTS

Three patients (two males and one female) aged between 39 and 61 presented with renal masses detected by physical examination or imaging. Macroscopically, the tumors were well-demarcated, with a fibrous capsule and a grayish-yellow to brown, solid, medium-texture cut surface. Microscopically, the tumor cells were polygonal to oval and were separated by thin-walled branching capillaries into sheets and nests. The cells exhibited abundant, translucent, or pale pink cytoplas. Immunohistochemical (IHC) staining showed diffuse positivity for S-100 protein (3/3), Vimentin (3/3), α-Inhibin (3/3), and NSE (3/3) in all cases, with focal positivity for AE1/AE3, EMA, CD10, and PAX-8. Staining for SMA, CgA, Syn, HMB-45, and Melan-A was negative. CD31 and CD34 highlighted an abundant vascular network. NGS revealed TSC1 gene alterations in all 3 cases, with no VHL gene mutation detected.

CONCLUSIONS

Primary renal HB is a rare mesenchymal tumor that requires differentiation from clear cell renal cell carcinoma (CCRCC) using morphological, IHC markers, and genetic testing when necessary. TSC1 could be a specific molecular hallmark of renal HB. Additional case data is required to better understand the molecular genetic alterations of the disease.

Recurrent Tuberous Sclerosis Complex/Mammalian Target of Rapamycin Mutations Define Primary Renal Hemangioblastoma as a Unique Entity Distinct From Its Central Nervous System Counterpart

ABSTRACT

Renal hemangioblastoma (HB) is a rare subset of HBs arising outside of the central nervous system (CNS), with its molecular drivers remaining entirely unknown. There were no significant alterations detected in previous studies, including von Hippel-Lindau gene alterations, which are commonly associated with CNS-HB. This study aimed to determine the real molecular identity of renal HB and better understand its relationship with CNS-HB. A cohort of 10 renal HBs was submitted for next-generation sequencing technology. As a control, 5 classic CNS-HBs were similarly analyzed. Based on the molecular results, glycoprotein nonmetastatic B (GPNMB) immunohistochemistry was further performed in the cases of renal HB and CNS-HB. Mutational analysis demonstrated that all 10 renal HBs harbored somatic mutations in tuberous sclerosis complex 1 ( TSC1 , 5 cases), TSC2 (3 cases), and mammalian target of rapamycin (2 cases), with the majority classified as pathogenic or likely pathogenic. The CNS-HB cohort uniformly demonstrated somatic mutations in the von Hippel-Lindau gene. GPNMB was strong and diffuse in all 10 renal HBs and completely negative in CNS-HBs, reinforcing the molecular findings. Our study reveals a specific molecular hallmark in renal HB, characterized by recurrent TSC/mammalian target of rapamycin mutations, which defines it as a unique entity distinct from CNS-HB. This molecular finding potentially expands the therapeutic options for patients with renal HB. GPNMB can be considered for inclusion in immunohistochemical panels to improve renal HB identification.