Sporadic hemangioblastoma of the kidney: an underrecognized pseudomalignant tumor?

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.

Polycythemia Secondary to Renal Hemangioblastoma: A Case Report and Literature Review

Secondary polycythemia is a paraneoplastic syndrome observed in tumors with excessive erythropoietin (EPO) production. Renal cell carcinoma (RCC) and cerebellar hemangioblastoma are the 2 most well-known tumors to induce secondary polycythemia. Hemangioblastomas occurring in the kidney are rare. In this work we present a case of renal hemangioblastoma that caused erythrocytosis in a 19-year-old man. We demonstrated intratumoural EPO production by immunohistochemistry, and conducted whole-exome sequencing to evaluate possible genetic alterations that reported to induce tumor-related polycythemia. In spite of an indolent clinical behavior, renal hemangioblastoma is difficult to differentiate from RCC not only clinically, but also histopathologically. Given that RCC is the most well-known renal tumor to induce erythrocytosis, the uncommon manifestation of polycythemia in renal hemangioblastoma, as shown in our case, can cause further diagnostic challenges. Renal hemangioblastoma should be listed in the differential diagnoses of renal tumors presenting with erythrocytosis, apart from the most common RCC.

Clinicopathological and molecular features of renal cell carcinomas with haemangioblastoma-like features distinct from clear cell renal cell carcinoma

AIMS

Haemangioblastomas arise in the central nervous system. Rarely, haemangioblastomas may develop in extra-neural sites, such as the kidneys. A few reported cases of renal cell carcinomas (RCCs) with haemangioblastoma-like features have exhibited both clear cell renal cell carcinoma (CCRCC)- and haemangioblastoma-like components. The clinicopathological and molecular characteristics of RCCs with haemangioblastoma-like features were analysed, focusing on VHL alterations, in comparison with CCRCCs partially resembling haemangioblastoma.

METHODS AND RESULTS

Four RCCs with haemangioblastoma-like features and five CCRCCs partially resembling haemangioblastoma were included. The RCCs with haemangioblastoma-like features were indolent and lacked adverse prognostic factors. All RCCs with haemangioblastoma-like features had a well-circumscribed appearance and a thick fibromuscular capsule, with fibromuscular bundles extending into the tumour to varying degrees in the three tumours. Each RCC with haemangioblastoma-like features exhibited CCRCC-like areas with indistinct tubular structures and foci of haemangioblastoma-like areas, in which vessels and short spindle cells overwhelmed tumour cells. Whereas haemangioblastoma-like areas in the CCRCCs partially resembling haemangioblastoma exhibited sparse vessels and spindle cells and distinct clear cells. The RCCs with haemangioblastoma-like features exhibited a unique immunohistochemical profile, with positive staining for inhibin-α, S100, carbonic-anhydrase-9, keratin7, and high molecular weight keratin and negative staining for (alpha-methylacyl-CoA racemase) AMACR. RCC with haemangioblastoma-like features did not display any VHL alterations, including VHL mutation, 3p LOH, and methylation of the VHL promoter region, and the two tumours harboured a likely oncogenic missense variant of MTOR (c.7280T>G).

CONCLUSION

The histopathological, immunohistochemical, and molecular findings suggest that RCC with haemangioblastoma-like features is a distinct entity from CCRCC.

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.

Clinicopathological analysis of extraneural sporadic haemangioblastoma occurring in the tongue

Haemangioblastoma is a morphologically distinctive tumour with uncertain histogenesis, typically occurring in the cerebellum, brain stem or spinal cord and less commonly in extraneural locations. Here, we present a case of haemangioblastoma occurring in the tongue, which is the first reported case in terms of the pathogenic site. The tumour was morphologically indistinguishable from central nervous system haemangioblastoma, that is, neoplastic stromal cells with cytoplasmic vacuolisation and abundant small vessels. Immunohistochemical studies revealed that the tumour cells were positive for S100, NSE, CD56, Syn, EMA, vimentin and α-inhibin, while negative for CK, SMA, factor Ⅷ, D2-40 and GFAP. Immunostainings for CD34 and CD31 outlined the rich and delicate vascular channels. Ki-67 expression was presented in approximately 3% of tumour cells. Primary haemangioblastoma has not been previously described at this site, and this case emphasises the need to consider haemangioblastoma in the differential diagnoses of neoplasms occurring in the tongue.

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.

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.

Primary Renal Mesenchymal Neoplasms in Nephrectomy Specimens: A 16-Year Survey of Primary and Incidental Cases From a Single Institution

Context. Primary renal mesenchymal neoplasms are rare but diverse. Several neoplasms of mesenchymal derivation can arise as a primary renal mass; however, incidental tumors are identified in nephrectomies performed for end-stage renal disease or other malignant epithelial renal neoplasms. In this article, we document their frequencies with demographic information in nephrectomy specimens. Design. We retrospectively searched our database for nephrectomy specimens from the year 2000 to 2016. Results. A total of 224 cases were identified with an incidence rate of 4.4% (224/5128). One hundred ninety (85%) neoplasms were benign, 27 (12%) were malignant, and 7 (3%) were of intermediate biologic behavior. The majority of cases occurred in adults (93%, 208/224), and 39% of cases represented an incidental finding. The most common neoplasms were angiomyolipoma (58%) and renomedullary interstitial cell tumor (17%). Malignant mesenchymal kidney tumors are rare (0.39% of nephrectomy specimens). The most common adults' malignant tumors in our survey were synovial sarcoma and Ewing's sarcoma. Conclusion. Primary renal mesenchymal tumors are rare and are mostly benign in nature with many incidentally identified lesions. They arise in different age groups with malignant lesions usually presenting at a younger mean age.

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).

Extraneural hemangioblastoma of the kidney: the challenge for clinicopathological diagnosis

Background

Hemangioblastoma is a benign cerebellar tumour which may occur as a sporadic entity or in association with von Hippel-Lindau (VHL) disease in approximately 25% of cases. Renal hemangioblastoma (RH) is an extremely rare and newly recognised tumour. Here, we describe five cases of RH, one discovered by CT in an accident and the other four detected during routine examinations.

Methods

Five cases of renal hemangioblastoma retrieved from the Department of Pathology, Fudan University Shanghai Cancer Center were studied and the literatures were reviewed. Immunohistochemistry was used to differentiate and confirm this tumour.

Results

Pathological examination following tumour resection revealed RH in all cases, the first patient was also diagnosed with renal cell carcinoma (RCC), suggesting the possibility of VHL syndrome, but PCR sequencing analysis of the VHL gene confirmed no mutation in any of the three exons, implying sporadic disease .Histologically, the tumours were circumscribed, composed of sheets of oval or polygonal cells and a prominent vascular network. Tumour cells had pleomorphic nuclei, but mitotic figures were rare. The diagnosis of hemangioblastoma was confirmed by immunohistochemistry.

Conclusions

RH is very rare and is challenging to differentially diagnose. Distinguishing RCC and RH is difficult and each has a different prognosis, so differentiating between them is essential for avoiding over-diagnosis and unnecessary treatment.

Brachyury: a diagnostic marker for the differential diagnosis of chordoma and hemangioblastoma versus neoplastic histological mimickers

Brachyury is a transcription factor which is required for posterior mesoderm formation and differentiation as well as for notochord development during embryogenesis. Due to its expression in the neoplastic cells of chordoma, a malignant tumour deriving from notochordal remnants, but not in tumors showing a similar histology, brachyury has been proposed as a diagnostic marker of this neoplasia. Though commonly considered a hallmark of chordoma, the expression of brachyury has been also documented in the stromal cells of hemangioblastoma (HBL), a slow growing tumor which may involve the central nervous system (CNS) and, rarely, the kidney. Herein we review the role of brachyury immunohistochemical detection in the identification and differential diagnosis of chordoma and HBL towards histological mimickers and suggest that brachyury is added to the panel of immunohistochemical markers for the recognition of HBL in routinary practice, principally in unusual sites.

PAX8 expression in sporadic hemangioblastoma of the kidney supports a primary renal cell lineage: implications for differential diagnosis

Hemangioblastoma is a benign, morphologically distinctive neoplasm of disputed histogenesis that typically occurs in the central nervous system either in the setting of von Hippel-Lindau disease or more often sporadically. Extraneural hemangioblastoma is exceptional and raises a challenging differential diagnosis. Herein, we report a primary renal hemangioblastoma occurring in 51-year-old woman without stigmata of von Hippel-Lindau disease. Histologically, the tumor was composed of sheets of polygonal epithelioid stromal cells with ample pale or eosinophilic, vacuolated cytoplasm in an arborizing capillary network. Tumor cells showed variable nuclear pleomorphism, intranuclear cytoplasmic invaginations, scattered hyaline globules, and psammoma-like calcifications. Some areas showed branching hemangiopericytoma-like vessels with tumor cells radiating from the wall, while other areas were edematous and hyalinized with sparse stromal cells and abundant reticular vessels. Immunohistochemically, the tumor cells reacted strongly and diffusely with antibodies to PAX8, CD10, α-inhibin, S100 protein, neuron-specific enolase, and vimentin, and they showed focal positivity with antibodies to epithelial membrane antigen and AE1/AE3. Tumor cells were negative for CK7, CK8/18, RCC antigen, synaptophysin, chromogranin, c-kit, D2-40, HMB45, melan-A, cathepsin K, SMA, desmin, CD31, CD34, and estrogen and progesterone receptors. Positive immunoreactivity for PAX8 is unexpected and contrasts to central nervous system (CNS) hemangioblastomas, which are essentially always negative for PAX8. This novel finding adds support to the hypothesis that the immunoprofile of extraneural hemangioblastoma varies with site of origin, perhaps as a result of tumor cell lineage and retention of organ-specific markers or acquisition of site-specific antigens due to local factors.

Sporadic renal haemangioblastoma: Case report and review of the literature

Haemangioblastoma is a benign tumour which generally occurs in a relatively restricted area of the central nervous system. Renal haemangioblastoma are extremely rare. We report a rare case of renal haemangioblastoma occurring in a 61-year-old male with a solid mass, which was detected during a routine examination. The patient was asymptomatic and abdominal computed tomography (CT) revealed a solid mass in the right kidney. No definitive preoperative diagnosis could be established. Surgical resection of the tumour revealed sporadic renal haemangioblastoma by pathological examination. The patient was followed up at 1 year without any problems. We also present a supplementary review of previously published cases and literature.

Sporadic hemangioblastoma of the kidney: a rare renal tumor

Hemangioblastoma is a benign and morphologically distinctive tumor that can occur sporadically or in association with von Hippel-Lindau disease in approximately 25% of the cases, and which involves the central nervous system in the majority of the cases. Rare occurrences of hemangioblastoma in peripheral nerves and extraneural tissues have been reported. This report describes one case of sporadic renal hemangioblastoma happened in a 16-year-old Chinese female patient, presenting with hematuria, and low back pain. Histologically, the tumors were circumscribed, and composed of sheets of large polygonal cells traversed by arborizing thin-walled blood vessels. The diagnosis of hemangioblastoma was confirmed by negative immunostaining for cytokeratin, and positive staining for α-inhibin, S100 and neuron-specific enolase (NSE). This benign neoplasm which can be mistaken for various malignancies such as renal cell carcinoma, epithelioid hemangiopericytoma and epithelioid angiomyolipoma, deserves wider recognition for its occurrence as a primary renal tumor.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5445834246942699.

Sporadic haemangioblastoma of the kidney with rhabdoid features and focal CD10 expression: report of a case and literature review

We present here an intriguing case of sporadic renal haemangioblastoma occurring in a 61-year-old male. The tumor consisted of nests of polygonal cells and abundant capillary networks. The neoplastic cells generally showed abundant eosinophilic cytoplasm and prominent eccentric nuclei, resembling the rhabdoid cells. Pronounced intranuclear cytoplasmic pseudoinclusions were another significant feature seen. NSE, a-inhibin and S100 were positive in tumor cells and particularly, focal CD10 expressions were observed. This is possibly the first reported case of a haemangioblastoma showing a rhabdoid phenotype and CD10 immunopositivity. Malignant rhabdoid tumor and renal cell carcinoma with rhabdoid features were probably the most challenging mimics need to be differentiated. The result of focal CD10 staining in our case may further lead to confusion with renal cell carcinoma. To avoid misdiagnosis, more considerations should be attached to the rare neoplasm.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1068858553657049.

Sporadic hemangioblastoma of the kidney in a 29-year-old man

Hemangioblastoma of the kidney is a rare, newly recognized tumor with morphological features similar to its cerebellar counterpart. There have been only 4 cases reported in the literature in English, all of them occurring in middle-aged to elderly patients. Here, we report a case of renal hemangioblastoma in a young adult without clinical evidence of von Hippel-Lindau disease. The tumor was composed of polygonal cells with mildly eosinophilic to clear cytoplasm and a rich vascular network. Immunohistochemical staining revealed a typical profile (positivity for α-inhibin, neuron-specific enolase and S100; negative results for epithelial membrane antigen, HMB-45, and Melan-A), which confirmed the diagnosis. Despite the similarity to renal-cell carcinoma in morphology, hemangioblastoma of the kidney is clinically indolent. Correct recognition of this pathological entity is important to avoid overdiagnosis and unnecessary clinical treatment.