Extraneural hemangioblastoma of the kidney: the challenge for clinicopathological diagnosis

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.

Sporadic Renal Hemangioblastoma: A Case Report of a Rare Entity

Hemangioblastoma, also known as capillary hemangioblastoma, is a rare benign mesenchymal tumor commonly found in the central nervous system (CNS). It can also manifest in various organs, including the kidney. Renal hemangioblastoma (RH) is often associated with Von Hippel-Lindau (VHL) disease, but sporadic occurrences are observed infrequently. While RH is usually asymptomatic, it can also cause abdominal pain and hematuria. In this study, we present a case of an elderly patient without history of VHL but complaining of abdominal pain for three days. Serological evaluations were unremarkable, and a CT scan identified a 2.4 cm mixed solid-cystic mass lesion on the left kidney's superior aspect. The patient subsequently underwent a biopsy followed by lesion ablation. Microscopic analysis revealed sheets of eosinophilic cells with ovoid nuclei, showing focal rhabdoid and spindle cell features, with an intricate capillary network. Focal nuclear atypia without necrosis or mitosis was noted. Immunohistochemistry (IHC) demonstrated positive staining for inhibin, S100, PAX8, and vimentin, along with patchy positivity for CD10 and RCC. Negative staining was observed for cytokeratin AE1/AE3, CK7, EMA, CK8/18, desmin, and HMB-45. The overall morphological characteristics and distinct IHC markers were consistent with RH. Although its pathogenesis remains unclear because of its rarity, distinguishing RH from renal cell carcinoma is crucial. IHC markers facilitate differentiation among lesions. The preferred treatment involves ablation or partial nephrectomy. Further assessment for possible VHL syndrome is essential, considering the distinct management approaches for sporadic and VHL-linked RH.

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

Tumors exhibiting histopathological findings similar to those of hemangioblastoma of the central nervous system (CNS-HB) rarely develop in the kidneys. Currently, renal hemangioblastoma (RHB) is considered analogous to CNS-HB; however, they differ in gross appearance, as well as immunohistochemical and molecular findings. In contrast, some renal cell carcinomas reportedly comprise distinct, clear cell renal cell carcinoma (CCRCC)- and hemangioblastoma (HB)-like areas. Initially, renal cell carcinomas with HB-like features (RCC-HBs) were considered a morphological variant of CCRCC owing to their diverse histological findings. However, the immunohistochemical and molecular findings of RCC-HBs suggest that RCC-HB is distinct from CCRCC. Additionally, one of the RCC-HBs had a focal leiomyomatous stroma and TSC2 variant, suggesting that RCC-HB and RCC with fibromyomatous stroma (RCC-FMS) might belong to the same disease entity. Therefore, we comprehensively reviewed the clinical, pathological, and molecular features of RHB, RCC-HB, and the related tumors and discussed the similarities, differences, and relationships between them. We believe that our review would serve as a foundation for further investigation on elucidating the relationship between CNS-HB, RHB, RCC-HB, and RCC-FMS.

Adrenal hemangioblastoma

Hemangioblastoma (HB) is a rare benign tumor that most commonly occurs in the cerebellum. HB is composed of neoplastic stromal cells and abundant small vessels. However, the exact origin of stromal cells is controversial. Extraneural HBs have been reported in a small series, and peripheral HBs arising in the adrenal gland are extremely rare. Herein, we report a case of sporadic adrenal HB in a 54-year-old woman. The tumor was a well-circumscribed, yellow mass measuring 4.2 cm in diameter. Histologically, the tumor was composed of small blood vessels and vacuolated stromal cells with clear cytoplasm. On immunohistochemical stain, the stromal cells were positive for S-100 protein, neuron-specific enolase, and synaptophysin. The tumor did not reveal mutation of VHL alleles. We herein present a case of HB of the adrenal gland and review of the literature.

Primary hemangioblastoma of the kidney with molecular analyses by next generation sequencing: a case report and review of the literature

Background

Hemangioblastoma is an indolent mesenchymal tumor most frequently occurring in the central nervous system (CNS), but can also arise extraneuraxially, as part of Von Hippel-Lindau (VHL) disease or in sporadic tumors. Extraneuraxial hemangioblastomas occur outside the central nervous system. It includes tumors arising from the nervous paraneuraxial structures and visceral organs. Sporadic hemangioblastoma of the kidney, a rare subset of extraneuraxial hemangioblastomas, is an under-recognized renal neoplasm. There have been only 25 cases described to date in the English language literature. We report herein one additional sporadic tumor in a patient without VHL disease.

Case presentation

A 61 year old male presenting with gross hematuria was found to have a 3.5 cm renal mass at the lateral mid to lower pole of the left kidney on computed tomography urogram. The patient underwent a partial nephrectomy for the mass. Pathological examination showed a well-circumscribed non-encapsulated tumor composed of sheets of large polygonal cells traversed by a rich vascular network. The tumor cells showed clear to eosinophilic cytoplasm and overall bland nuclei. The diagnosis of hemangioblastoma was confirmed by positive immunostaining for alpha-inhibin, S100, neuron-specific enolase, and PAX8. No significant gene mutations, including VHL gene and copy number changes were detected in the tumor using next generation sequencing supporting the diagnosis of sporadic renal hemangioblastoma.

Conclusion

Sporadic renal hemangioblastoma is a rare subset of extraneuraxial hemangioblastomas. We report one such tumor in a patient without clinical or molecular evidence of VHL disease. The literature was reviewed to better understand the clinical, radiological, pathological, and molecular features of this neoplasm. The majority of renal hemangioblastomas showed positive immunostaining for PAX8, which supports the idea that the immunoprofiles of extraneuraxial hemangioblastomas can vary depending on sites of origin. Diagnosis of renal hemangioblastoma is challenging because of its rarity and overlapping microscopic and immunophenotypic features with other renal tumors, including clear cell renal cell carcinoma. In some cases, molecular or genetic studies may be necessary to obtain an accurate diagnosis. Since renal hemangioblastoma is clinically benign, recognition of this pathological entity is important to avoid unnecessary over-treatment.

Sporadic hemangioblastoma of the kidney: a clinicopathologic study of three cases and a literature review

Much attention has been paid to renal hemangioblastoma, but there are still challenges in its differential diagnosis. Three cases (2 men, 1 woman; age: 40–56 years) presented with renal tumors. The tumors were surrounded by a thick fibrous capsule, well-demarcated from the surrounding renal parenchyma, and composed of sheets or nests of polygonal to short spindle-shaped tumor cells with a rich capillary network. In cases 1 and 3, the large polygonal tumor cells contained abundant pale or eosinophilic cytoplasm, and some possessed intracytoplasmic lipid vacuoles. In case 2, tumor cells were characterized by a uniform size, mild, clear, or lightly stained cytoplasm, and typical "clear cell" appearance. Immunohistochemistry revealed that the polygonal stromal cells were strongly and diffusely positive for α-inhibin, neuron-specific enolase (NSE), S100 protein, and vimentin. Cluster of differentiation (CD)10 and paired box gene (PAX)8 were positive, while epithelial membrane antigen (EMA) and cytokeratin (CK) were focally positive in case 3. CD34 and CD31 outlined the contours and distribution of the vascular networks. Renal hemangioblastoma is rare and prone to misdiagnosis; more attention should be paid to the morphological features and reasonable application of immunohistochemistry in the diagnosis of hemangioblastoma.

CT and MRI characteristic findings of sporadic renal hemangioblastoma: Two case reports

RATIONALE

Hemangioblastomas in the kidney are rare. Although a few cases of renal hemangioblastoma (RH) have been reported, the content of these articles mainly focused on clinical and pathological research, with minimal descriptions of radiologic findings. Moreover, there are no descriptions of magnetic resonance imaging (MRI) with enhancement of this condition. Herein, we report 2 cases of RH with computed tomography (CT) and MRI findings.

PATIENT CONCERNS

Two patients presented to our institution because of dull pain in the left abdomen, and a mass in the left kidney was found by ultrasound examination in each case. The patient had no special family history. Physical examination revealed no obvious tenderness or percussion pain in the renal and ureteral walking areas, and there was no obvious mass. Routine blood and urine tests were normal, and the serum tumor markers were negative. No obvious lesions were found on imaging of the other body parts.

DIAGNOSIS

Similar radiologic findings were observed in both cases and mimicked those of cavernous hemangiomas of the liver, including peripheral nodular enhancement in the corticomedullary phase, progressive centripetal enhancement in the nephrographic and delayed phases, and occasional complete "filling in" in the delayed phase. We made a radiologic diagnosis of renal clear cell carcinoma for patient 1 and suspected renal clear cell carcinoma for patient 2, but the pathological results showed RH.

INTERVENTIONS

Given the suspicion of renal cell carcinoma, both patients underwent partial nephrectomy.

OUTCOME

The recovery of the two patients was uneventful, and there was no evidence of local recurrence or metastasis many years after surgery.

LESSONS

RH is a rare benign tumor that can be easily misdiagnosed as clear cell carcinoma. Characteristic CT and MRI manifestations may improve preoperative diagnostic accuracy to avoid surgery or indicate nephron-sparing surgery.

Renal Hemangioblastoma with Mixed Mullerian tumour of endometrium: A tale of two rare primary tumours

INTRODUCTION

Renal hemangioblastoma (RH) is a very rare benign tumour. Hemangioblastoma most commonly occurs in the central nervous system (CNS), and only few cases of RH have been reported as they occur most commonly as asymptomatic masses found incidentally. Mixed Mullerian tumour (MMT) of the uterus is a rarer and aggressive form of uterine malignancy. The detection of two primary rare tumours incidentally is a rare entity.

CASE PRESENTATION

A 50-year-old female presented with abnormal uterine bleeding which on endometrial sampling was diagnosed as a rare variety of endometrial cancer, i.e. MMT or uterine carcinosarcoma. On preoperative imaging, a renal mass was also detected which was highly vascular and was mimicking renal cell carcinoma (RCC). Fine needle aspiration cytology (FNAC) was done from the renal mass to differentiate between RCC and metastasis, but it showed only blood cells. Patient underwent staging laparotomy for endometrial cancer and frozen section examination of the renal mass which was inconclusive with few atypical cells, and thus, patient underwent radical nephrectomy too. Histopathological examination revealed it to be a RH which is a very rare benign tumour.

DISCUSSION

RH is a rare benign tumour which does not require any treatment in majority of the patients. Only 26 cases of RH outside the CNS have been reported till date. MMT is a rare aggressive uterine tumour with an incidence of 1-2 % of all uterine neoplasms, which metastasizes early, and thus, early identification and treatment is the key. RH needs to be differentiated from RCC to avoid over treatment. Morphological findings are similar in RCC and RH; preoperative FNAC, PET scan, and intraoperative frozen section can be utilized to differentiate the two, in well-circumcised tumours and high index of suspicion. Occurrence of renal mass as an incidental finding in the preoperative work up of uterine malignancy directed us to the differentials of metastasis or another histologically distinct primary tumour. The presence of two rare primary tumours, i.e. RH and MMT in the same patient which are unrelated, is a rare entity.

Sporadic renal hemangioblastoma: A case report of a rare benign renal tumor

In renal tumors, suspicious for renal cell carcinoma, where there is any doubt and discrepancy between morphology and immune profile, we recommend performing further immunohistochemical staining for pan-cytokeratin, S100, NSE, and inhibin-alpha. Thus, follow-up overtreatment can be avoided in cases of benign kidney tumors.

Extraneuraxial hemangioblastoma: A clinicopathologic study of 10 cases with molecular analysis of the VHL gene

Less than 250 extraneuraxial hemangioblastomas occurring in paraneuraxial or peripheral sites have been reported to date, sporadically or in the setting of von Hippel-Lindau disease. Seventeen such cases underwent molecular genetic analysis, using either the patient's peripheral blood in 9 cases or paraffin embedded tumor tissue in the rest. VHL gene mutations were documented in 3/9 cases in which DNA from peripheral blood lymphocytes was used, all with clinically manifest von Hippel-Lindau disease; instead, no VHL gene alterations were found in all of the 8 cases with sporadic extraneuraxial hemangioblastoma in which DNA from tumor tissue was analyzed. Our aim is to investigate the molecular genetic profile of the VHL gene in extraneuraxial hemangioblastoma using paraffin embedded tumor tissues. The clinical features, histopathology, and molecular investigations of 10 extraneuraxial hemangioblastomas (7 females, 3 males; median age: 47 years) are presented herein. The histopathologic diagnosis was supported by immunohistochemistry (10/10) and electron microscopy (4/10). Molecular genetic analysis was conducted (10/10) for VHL gene mutations, LOH, and gene promoter methylation. Two of the present cases were already published with only limited or no molecular investigations. Four tumors of the present series were paraneuraxial, and 6 peripheral (2 involved soft tissues, and 4 the kidney). One tumor was von Hippel-Lindau disease-associated, 1 was classified as "hemangioblastoma-only VHLD", 7 were sporadic, and one was unknown. All were histopathologically analogous to their counterpart located inside the central nervous system. Immunophenotypically, all tumors expressed vimentin, S-100, NSE, and alpha-inhibin (10/10). Ultrastructurally, unbound lipid droplets filled the cytoplasms of the stromal cells. Molecular analysis revealed 3 inactivating mutations (1 germline, two somatic) in the coding sequence of the VHL gene in 2 different extraneuraxial hemangioblastomas, and LOH in 4 (two as a double hit), all non-renal extraneuraxial hemangioblastomas. Methylation analysis failed to disclose promoter methylation in any case. In conclusion, we report eight new cases from the wide category of extraneuraxial hemangioblastomas (4 paraneuraxial, and 4 renal), one of which was von Hippel-Lindau disease-associated and 7 sporadic. VHL gene alterations were found not only in the von Hippel-Lindau disease-associated tumor, but - for the first time - also in 3 sporadic ones, two of which with novel mutations.

Extraneuraxial Hemangioblastoma: Clinicopathologic Features and Review of the Literature

Extraneuraxial hemangioblastoma occurs in nervous paraneuraxial structures, somatic tissues, and visceral organs, as part of von Hippel-Lindau disease (VHLD) or in sporadic cases. The VHL gene plausibly plays a key role in the initiation and tumorigenesis of both central nervous system and extraneuraxial hemangioblastoma, therefore, the underlying molecular and genetic mechanisms of the tumor growth are initially reviewed. The clinical criteria for the diagnosis of VHLD are summarized, with emphasis on the distinction of sporadic hemangioblastoma from the form fruste of VHLD (eg, hemangioblastoma-only VHLD). The world literature on the topic of extraneuraxial hemangioblastomas has been comprehensively reviewed with ∼200 cases reported to date: up to 140 paraneuraxial, mostly of proximal spinal nerve roots, and 65 peripheral, 15 of soft tissue, 6 peripheral nerve, 5 bone, and 39 of internal viscera, including 26 renal and 13 nonrenal. A handful of possible yet uncertain cases from older literature are not included in this review. The clinicopathologic features of extraneuraxial hemangioblastoma are selectively presented by anatomic site of origin, and the differential diagnosis is emphasized in these subsets. Reference is made also to 10 of the authors' personal cases of extraneuraxial hemangioblastomas, which include 4 paraneuraxial and 6 peripheral (2 soft tissue hemangioblastoma and 4 renal).