Peripheral Hemangioblastoma: Clinicopathologic Characterization in a Series of 22 Cases

Brachyury expression is highly specific for chordoma: A tissue microarray study involving 14,976 cancers from 135 different tumor types and subtypes

Brachyury protein plays a role in defining the midline of bilaterian organisms. Commonly expressed in chordomas, brachyury immunohistochemistry is used to distinguish chordomas from their differential diagnoses. However, brachyury expression has also been described to frequently occur in other cancer entities. To better comprehend the role of brachyury expression in cancer, a tissue microarray containing 14,976 samples from 135 different tumor entities and 608 samples of 76 different normal tissue types were analyzed by immunohistochemistry. Brachyury staining was found in 55 (0.44 %) of the 12,409 interpretable tumor samples, including 37 (0.3 %) with weak, 10 (0.08 %) with moderate, and 8 (0.06 %) with strong positivity. Brachyury staining strongly predominated in chordomas. Of ten chordomas, 7 were strongly and 3 moderately positive. Only 5 of the 134 analyzed further tumor categories showed brachyury staining, 4 of which originated from testicular germ cells. Brachyury positivity occurred in 21.4 % of 42 yolk sac tumors, 15.2 % of 46 embryonal carcinomas, 4.4 % of 562 seminomas, and 2.4 % of 41 teratomas of the testis. Our data support the previously suggested high specificity of brachyury for chordoma detection, and demonstrate that germ cell tumors represent the only additional group of unrelated cancer entities expressing brachyury at a significant level.

Immunohistochemical Expression of PAX8 in Central Nervous System Hemangioblastomas: A Potential Diagnostic Pitfall for Neuropathologists

The histologic differential diagnosis between intracranial hemangioblastoma (HB) and metastatic clear cell renal cell carcinoma may be challenging, especially considering that both tumors exhibit clear cell morphology and can be associated with vHL mutation and/or Von Hippel-Lindau syndrome. As the execution of immunohistochemical analyses is often mandatory, the expression of PAX8 has been traditionally considered a reliable marker of metastatic clear cell renal cell carcinoma, being consistently negative in intracranial HB. However, as in recent years, some cases of PAX8-positive HBs have been reported in the literature; we studied the expression of this antibody on a series of 23 intracranial HB, showing that about 40% of these tumors may express PAX8 and that this immunoreactivity is often focal and weak. We would like to emphasize that the possibility of a PAX8-positive intracranial HB does exist and must be taken into account by neuropathologists to avoid misdiagnoses; in this regard, a broader immunohistochemical panel also including CD10, Inhibin-α, PAX2, S100, and anti-Renal cell carcinoma (RCC) antibody is highly recommended.

Uncommon Tumors of the Lung: Recently Described and Rediscovered Tumors

CONTEXT.—

The great majority of primary pulmonary neoplasms are represented by non-small cell carcinomas-adenocarcinoma and squamous cell carcinoma. In addition, there is another group of neoplasms such as those of neuroendocrine origin that also represent a meaningful subset of primary lung neoplasms. Basically, any other tumor that is not in these groups of tumors may represent an unusual lung neoplasm.

OBJECTIVE.—

To highlight more recently described unusual tumoral entities that may represent a challenge in diagnosis and that require awareness of their existence.

DATA SOURCES.—

This is a review of 3 different entities: bronchiolar adenoma, adenofibroma, and hemangioblastoma-like clear cell stromal tumor. These tumoral conditions are rare, and a review of the literature is presented. The most relevant morphologic, immunohistochemical, and molecular aspects of bronchiolar adenoma, adenofibroma, and hemangioblastoma-like clear cell stromal tumor are presented. The difficulty of arriving at an unequivocal diagnosis in small biopsies is highlighted.

CONCLUSIONS.—

The 3 entities represent uncommon tumors occurring primarily in the lung and a diagnostic challenge not only in biopsy specimens but also often in surgically resected specimens. The use of immunohistochemical stains and in some cases of molecular diagnostics is of aid in arriving at final interpretation.

What Is New in Pathologic Diagnosis and Classification of the Common Renal Cell Neoplasms?

Diagnostic challenges remain among the common renal cell carcinoma (RCC) subtypes. High-grade clear cell RCC may have deceptive patterns, for example BAP1-deficient tumors. Subtyping type 1 and 2 papillary RCC is no longer recommended, as former type 2 tumors may now be contain other diagnostic entities, such as FH-deficient RCC, MITF family RCC, or others. Clear cell papillary tumor is no longer considered carcinoma due to its highly favorable behavior. However, imperfect examples are best considered clear cell RCC. Oncocytic renal neoplasm of low malignant potential has been proposed as a borderline category in the absence of overt malignant features.

Mesenchymal Neoplasms of the Kidney and Perinephric Soft Tissue

Mesenchymal neoplasms of the kidney present challenges because they are uncommon, and because perinephric soft tissue biopsies are sometimes submitted as "kidney" masses, causing diagnostic confusion. Here, the author thoroughly reviews mesenchymal neoplasms of the kidney, including metanephric stromal tumor, classic and cellular congenital mesoblastic nephroma, anaplastic sarcoma and clear cell sarcoma of the kidney, malignant rhabdoid tumor, PEComa/angiomyolipoma, and anastomosing hemangioma. The author also discusses perinephric myxoid pseudotumor of fat, as well as diagnostic pitfalls presented by well-differentiated/dedifferentiated liposarcoma and sarcomatoid carcinoma.

Emerging fusion-associated mesenchymal tumours: a tabular guide and appraisal of five 'novel' entities

AIMS

The field of molecular pathology has undergone significant advancements in the clinical impact of sarcoma diagnosis, resulting in challenges to nosology of bone and soft tissue tumours. The surge in molecular data has led to the identification of novel fusions and description of new 'entities'. To illustrate this, we have selected five emerging entities with novel fusions: clear cell stromal tumour of the lung with YAP1::TFE3 fusion, GAB1::ABL1 fusion spindle cell neoplasm, NUTM1-rearranged sarcomas, NR1D1-rearranged sarcomas and calcified chondroid mesenchymal neoplasms.

METHODS

Literature for the relevant case reports and case series of these five entities were reviewed and clinicopathological data was collected. Additionally, this review includes a table format of recently described fusion-associated mesenchymal neoplasms.

RESULTS

The morphological and immunohistochemical features, along with diagnostic challenges, are discussed for each entity.

CONCLUSIONS

Here, we have provided a review of selected emerging mesenchymal neoplasms, which of these neoplasms will meet the threshold to be 'new entities' remains to be determined.

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.

Clear cell stromal tumor of the lung: Report of 3 cases with emphasis on multifocal tumors

We describe 3 patients with clear cell stromal tumor (CCST) of the lung, all of whom presented with multifocal disease. The patients were 2 men and 1 woman aged 47-58 years (mean, 54 years). Two patients had evidence of autoimmune disease and their pulmonary disease was an incidental finding; one patient presented with non-specific respiratory symptoms. Radiologic imaging revealed multiple pulmonary nodules in all patients. Histologically, the tumors were solid-cystic and composed of cytologically bland, medium-sized ovoid to spindle cells with eosinophilic to clear cytoplasm arranged in a subtle nested pattern. These tumor cells were set in a highly vascularized stroma. Occasional cytologic atypia with multinucleated tumor cells was noted but mitotic activity was low. An infiltrate of mixed inflammatory cells was apparent in all tumors. Immunohistochemical analysis demonstrated diffuse expression of vimentin and TFE3 in all cases. Next generation sequencing revealed the presence of YAP1::TFE3 fusion in 1/1 case. All patients have remained alive albeit with stable or progressive disease, 24-66 months after diagnosis. These cases highlight the existence of multifocal pulmonary CCST and seem to support the notion that multifocality in CCST may be associated with more protracted clinical course. Awareness of the existence of multifocal pattern is important for patient management and prognosis.

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.

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.

von Hippel-Lindau disease-related neoplasia with an emphasis on renal manifestations

von Hippel-Lindau (VHL) disease is characterized by biallelic inactivation of the VHL gene leading to abnormal or absent VHL protein function, and constitutive activation of hypoxia-inducible factors (HIF) that leads to pro-tumorigenic signaling. Individuals with VHL disease develop numerous cysts and tumors involving multiple organs including the kidneys, central nervous system, endolymphatic sac, lungs, pancreatobiliary system, adrenal glands, epididymis, and/or broad ligament. On histologic examination, these lesions show morphologic overlap as they are frequently characterized by cells with clear cytoplasm and prominent vascularity. In addition to distinguishing non-renal tumors from metastatic clear cell renal cell carcinoma, understanding site-specific histopathologic and immunophenotypic features of these tumors has several applications. This includes distinguishing VHL-related tumors from those that arise sporadically and lack VHL gene alterations, guiding further genetic workup, and helping distinguish between different genetic predisposition syndromes. In this context, immunohistochemical studies for markers such as paired box 8 (PAX-8), carbonic anhydrase 9 (CA9), and glucose transporter 1 (GLUT-1) have an important role in routine clinical practice and represent cost-effective diagnostic tools. The recent development of targeted therapeutics directed against HIF-mediated signaling represents a significant milestone in the management of VHL disease and highlights the importance of accurately diagnosing and characterizing the wide spectrum of VHL disease-associated lesions.

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.

Expression of Hemangioblast Proteins in von Hippel-Lindau Disease Related Tumors

Von Hippel-Lindau (VHL) disease is a hereditary tumor syndrome that targets a highly selective subset of organs causing specific types of tumors. The biological basis for this principle of organ selectivity and tumor specificity is not well understood. VHL-associated hemangioblastomas share similar molecular and morphological features with embryonic blood and vascular precursor cells. Therefore, we suggest that VHL hemangioblastomas are derived from developmentally arrested hemangioblastic lineage keeping their potential of further differentiation. Due to these common features, it is of major interest to investigate whether VHL-associated tumors other than hemangioblastoma also share these pathways and molecular features. The expression of hemangioblast proteins has not yet been assessed in other VHL-related tumors. To gain a better understanding of VHL tumorigenesis, the expression of hemangioblastic proteins in different VHL-associated tumors was investigated. The expression of embryonic hemangioblast proteins Brachyury and TAL1 (T-cell acute lymphocytic leukemia protein 1) was assessed by immunohistochemistry staining on 75 VHL-related tumors of 51 patients: 47 hemangioblastomas, 13 clear cell renal cell carcinomas, 8 pheochromocytomas, 5 pancreatic neuroendocrine tumors, and 2 extra-adrenal paragangliomas. Brachyury and TAL1 expression was, respectively, observed in 26% and 93% of cerebellar hemangioblastomas, 55% and 95% of spinal hemangioblastomas, 23% and 92% of clear cell renal cell carcinomas, 38% and 88% of pheochromocytomas, 60% and 100% of pancreatic neuroendocrine tumors, and 50% and 100% of paragangliomas. We concluded that the expression of hemangioblast proteins in different VHL-associated tumors indicates a common embryological origin of these lesions. This may also explain the specific topographic distribution of VHL-associated tumors.

Extraneuraxial Hemangioblastoma: An Unusual Soft Tissue Neoplasm that Mimics More Common Entities but Carries Distinct Clinical Implications

Hemangioblastoma, one of the characteristic tumors associated with Von Hippel-Lindau (VHL) disease, most often presents in the central nervous system (CNS) but can uncommonly arise in extraneuraxial, or previously referred to as peripheral, locations. Without the clinical context of known VHL disease, hemangioblastoma may not enter the differential for a soft tissue mass outside the CNS. Here, we present two patients with diagnostically challenging extraneuraxial hemangioblastoma to highlight the importance of considering this entity within the differential diagnosis of soft tissue neoplasms containing clear cells and delicate vasculature. We review the relevant diagnostic features, including a suggested immunohistochemical panel, along with the potential associated clinical implications of making this diagnosis. It is recommended that affected patients be offered genetic counseling to assess for underlying VHL disease.

Spinal cervical extradural hemangioblastoma

Spinal cervical extradural and intra-extradural hemangioblastomas are exceptional, with only nine reported cases. This study reviews the diagnostic and surgical problems of this rare entity. Two female patients, aged 80 years and 25 years, respectively, one with Von Hippel-Lindau disease (VHLD), experienced brachial pain and weakness. On magnetic resonance imaging, a dumbbell intra-extraspinal hemangioblastoma was evidenced. The surgical resection through posterior laminectomy resulted in clinical remission of brachial pain and weakness. The magnetic resonance aspect of a dumbbell lesion suggests a neurogenic tumor; the correct preoperative diagnosis is possible in individuals with VHLD. The surgical problems include high tumor vascularity, vertebral artery control, and nerve root preservation. However, the surgical excision results in clinical remission.

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.

Recurrent YAP1-TFE3 Gene Fusions in Clear Cell Stromal Tumor of the Lung

Clear cell (hemangioblastoma-like) stromal tumor of the lung (CCST-L) is a recently described distinctive rare pulmonary neoplasm of unknown histogenesis and molecular pathogenesis. Only 7 cases have been reported in 2 recent studies, although additional cases might have been reported under the heading of extraneural pulmonary hemangioblastoma. We herein describe 4 CCST-L cases, 3 of them harboring a YAP1-TFE3 fusion. The fusion-positive tumors occurred in 3 women, aged 29, 56, and 69 years. All presented with solitary lung nodules measuring 2.3 to 9.5 cm. Histologically, all tumors showed similar features being composed of relatively uniform medium-sized epithelioid to ovoid cells with clear cytoplasm and small round monomorphic nuclei. Scattered larger cells with enlarged hyperchromatic nuclei and marked pleomorphism were noted in 2 cases. The tumors were associated with a hypervascularized stroma with variable but essentially subtle resemblance to capillary hemangioblastoma and perivascular epithelioid cell tumor (PEComa). Immunohistochemistry was negative for all lineage-specific markers. Targeted RNA sequencing showed a YAP1-TFE3 fusion in 3 of 4 cases. All 3 tumors showed homogeneous nuclear TFE3 immunoreactivity. Two patients were disease free at 36 and 12 months. The third patient had biopsy-proven synchronous renal and hepatic metastases, but extended follow-up is not available (recent case). The fourth case lacking the fusion affected a 66-year-old woman and showed subtle histologic differences from the fusion-positive cases, but had comparable TFE3 immunoreactivity. CCST-L represents a distinctive entity unrelated to hemangioblastoma and likely driven by recurrent YAP1-TFE3 fusions in most cases. The relationship of our cases to the recently reported "hemangioblastoma-like" CCST-L remains to be determined. Analysis of larger series is paramount to delineate the morphologic spectrum and biological behavior of this poorly characterized entity.

Novel Clinical Insights into Spinal Hemangioblastoma in Adults: A Systematic Review

BACKGROUND

Hemangioblastomas (HBs) are well-vascularized, benign central nervous system tumors and the third most common primary spinal cord tumor after astrocytoma/ependymoma, occurring sporadically or as a part of autosomal dominant von Hippel-Lindau disease, in which tumors are often multiple and prone to relapse. Spinal HBs are commonly located in the cervical cord and associated with a syrinx formation. Owing to location and growth trends, they may cause significant neurological deficit, impairing quality of life. We conducted a systematic review to understand better clinical insights into spinal HB in adults and compare spinal HB versus posterior cranial fossa HB.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for conducting systematic reviews, we reviewed the English-language literature on adult spinal HB in the MEDLINE/PubMed database over the last 40 years.

RESULTS

We reviewed 237 articles on adult spinal HB and analyzed national and continental distribution, clinical symptoms, tumor location and presence of syringomyelia, treatment strategies and postoperative complications, histology and immunochemistry, and treatment outcomes. We compared individual characteristics in sporadic and von Hippel-Lindau disease spinal HBs. Finally, we compared features of posterior cranial fossa and spinal HBs.

CONCLUSIONS

Spinal cord HBs most commonly have a dorsal intramedullary location. Total surgical tumor resection is the first treatment option; preoperative embolization may be performed to reduce intraoperative bleeding and surgical time. HBs located in the spine have decreased mortality and rate of infection, but increased rates of cardiopulmonary complications compared with HBs in the posterior cranial fossa.

A pure extradural hemangioblastoma mimicking a dumbbell nerve sheath tumor in cervical spine: illustrative case

BACKGROUND

Spinal extradural hemangioblastomas (HBs) are quite uncommon, with most reported cases involving the thoracic and lumbar areas. Therefore, the presence of a dumbbell-shaped pure extradural cervical HB is exceptional, making preoperative diagnosis particularly challenging.

OBSERVATIONS

The authors report a case of a 27-year-old woman who presented to their outpatient clinic with progressive cervicobrachialgia and numbness in the left arm. Magnetic resonance imaging showed a C5-6 intradural extramedullary lesion, and, despite some atypical features, the diagnosis of a possible neurogenic tumor was made. A multidetector computed tomography scan and angiography confirmed the expansion and remodeling of the left neural foramen as well as the highly vascularized nature of the mass. Preoperative embolization of the lesion was performed. Complete tumor resection was accomplished, followed by a C5-6 posterior fusion. Histopathology and immunohistochemistry revealed an HB.

LESSONS

HBs should be considered among the differential diagnosis of cervical extradural tumors. Exhaustive preoperative workup and surgical planning are decisive in order to attain gross-total resection with favorable outcomes.

Hemangioblastoma of the Peripheral Nervous System: A Critical Analysis of Its Rarity in Von Hippel-Lindau Disease

Von Hippel-Lindau (VHL) disease is a multisystem disease cause by germline mutations of the VHL tumor suppressor gene. Hemangioblastomas are the most common manifestation of VHL disease and can occur in the central nervous system in up to 90% of these patients. By contrast, we found only one true case of a peripheral nervous system (PNS) hemangioblastoma in the setting of VHL. We explore the possible reasons behind the lack of PNS hemangioblastomas in VHL disease.

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.

Spinal extradural hemangioblastoma: A systematic review of characteristics and outcomes

Extradural spinal nerve root hemangioblastoma is a rare entity with very few cases reported in the literature. A comprehensive picture of the treatments and outcomes of the same is thus not available. A systematic search was done according to PRISMA guidelines. Search criteria included terms: spinal extradural hemangioblastoma, extradural hemangioblastoma, and spinal root hemangioblastoma. The parameters considered were treatment, motor, and sensory outcome, association with von-Hippel-Lindau (VHL) syndrome. Twenty-two studies (19 full text articles) were available for the review. A total of 39 cases of extradural spinal nerve root hemangioblastoma have been reported. These cases had a median age of 44 years with male predominance (2:1) and up to 48% occur in the thoracic level, similar to our case. Thirty-six percent of patients were associated with VHL syndrome. Surgical resection was the primary modality of treatment with embolization used in selected cases (20%). They had mean follow-up of 23 (±11) months. The prognosis was better than the intradural counterpart with no motor deficit and sensory deficit in only 9%. Preoperative identification of the extradural nature of this pathology and complete excision at the first surgery offers excellent outcomes compared to intradural lesion. Targeted embolization may be used in cases anticipated with high blood loss.

Hemangioblastoma-like Clear Cell Stromal Tumor of the Lung: A Clinicopathologic and Immunohistochemical Study of 5 Cases

Five cases of an unusual primary benign stromal tumor designated as hemangioblastoma-like clear cell stromal tumor of the lung are presented. The patients are 4 women and 1 man between the ages of 39 and 52 years of age (average: 45.5 y). The patients presented with nonspecific symptoms of cough, chest pain, or dyspnea. None of the patients had any prior history of malignancy or tumor elsewhere. Diagnostic imaging showed the presence of an intrapulmonary tumor. Lobectomy was performed in all 5 patients. Grossly, the tumors were well-demarcated but not encapsulated with focal areas of hemorrhage without necrosis. Histologically, low power examination showed a cellular proliferation alternating with discrete dilated vessels reminiscent of a vascular neoplasm. Higher magnification showed medium-sized cells with clear cytoplasm arranged in sheets and cords. Mitotic activity and marked cellular atypia were not present. A wide panel of immunohistochemical studies was performed including epithelial, neural, muscle, vascular, and neuroendocrine markers, all of which showed negative staining. Tumor cells showed positive staining for vimentin. In 2 cases, fluorescence in situ hybridization for the solitary fibrous tumor was performed and was negative. Clinical follow-up in 3 patients showed no evidence of recurrence. The cases herein presented highlight an unusual benign stromal tumor of the lung, which needs to be considered in the differential diagnosis of tumors with a clear cell and vascular appearance.

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.

Benign peripheral nerve tumors

Benign peripheral nerve tumors encompass a wide range of neoplasms and non-neoplastic tumor like lesions. Some of these lesions if not encountered in the setting of genetic syndromes, are occurring sporadically. The principles of oncology should be respectfully followed in every step of diagnostic approach and surgical management. Albeit, classified as benign, some of them do have different level of malignant potential, thus the treating physicians should be aware of that to avoid possible pitfalls with devastating outcomes. This article reviews the most common benign peripheral nerve tumors discussing the clinicopathological findings, imaging appearance and the current trend in their approach.

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).

Hypervascular Lesions of the Cerebellopontine Angle: The Relevance of Angiography as a Diagnostic and Therapeutic Tool and the Role of Stereotactic Radiosurgery in Management. A Comprehensive Review

BACKGROUND

The cerebellopontine angle (CPA) is a narrowed skull base area containing important cranial nerves and vessels and bordering with eloquent areas of the posterior fossa. Tumors of the CPA are a heterogeneous group and can have extradural, intradural/extra-axial, or intra-axial origins. Their vascular supply changes depending on their anatomic origin. Symptomatic, large CPA tumors require surgical resection in order to prevent irreversible, severe neurological damages. However, its tight and strategical location make surgery in the CPA very challenging and require appropriate pre-surgical planning. Pre-surgical diagnosis is of great importance as it allows us to choose the optimal management for the particular patient. This is of further significance when encountering high-risk lesions such as hypervascular tumors. Neurosurgeons should utilize every available pre-surgical diagnostic modalities as well as neo-adjuvant treatments in order to reduce such risks.

METHODS

We review all reported cases of hypervascular lesions of the CPA and discuss the roles of angiography and stereotactic radiosurgery in their management.

RESULTS

Three lesions of the CPA can be considered as truly hypervascular: hemangioblastomas, hemangiopericytomas and paragangliomas. All lesions share many radiological features. However, each lesion has a different anatomical origin and hence, has a characteristic vascular supply. Pre-surgical angiography can be utilized as a diagnostic tool to narrow down the differential diagnosis of a vascular CPA lesion, based on the predominant supplying vessel. In addition, pre-surgical embolization at time of angiography will narrow the associated surgical risks.

CONCLUSIONS

Angiography is a crucial diagnostic and therapeutic tool, helping both in narrowing the presurgical differential diagnosis and in controlling intraoperative bleeding. Because of the high surgical risks associated with resection of vascular tumors in the CPA, noninvasive treatments, such as stereotactic radiosurgery, also may have a crucial role.

Short-Spindled Cell Haemangioblastoma with CD34 Expression: New Histopathological Variant or Just a Stochastic Cytological Singularity?

Haemangioblastomas are neoplasms of uncertain histogenesis with cellular and reticular variants advocated in current lore. Herein we describe an intriguing cerebellar specimen with unusual traits including spindle cell morphology and CD34 positivity. A thirty-nine-year old man had an infratentorial tumour discovered incidentally and resected three times. In all the instances, histopathological diagnosis was haemangioblastoma; nonetheless, he had neither physical stigmata nor family history of von Hippel-Lindau disease. By histology, the lesion was composed of areas of conventional stromal cells admixed with territories populated by short-spindled cells packed in lobules, sometimes giving the appearance of gomitoli. Immunoperoxidase-coupled reactions confirmed the expression of inhibin A, neuron-specific enolase (NSE), PS100, and CD57 but also revealed focal immunolabeling for CD34, CD99, and FXIIIa. This case highlights the potential phenotypical diversity that can be found within these neoplasms. Rather than uncertain histogenesis, it may in fact reflect multiple lines of differentiation—histomimesis—prone to adopt unusual morpho- and immunophenotypes in a subset of haemangioblastomas.

Purely extradural spinal nerve root hemangioblastomas

Spinal nerve root hemangioblastomas present mostly as intradural-extradurally. Purely extradural spinal nerve root hemangioblastoma is a very rare entity. In this study, we aimed to analyze epidemiological perspectives of purely extradural spinal nerve root hemangioblastomas presented in English medical literature in addition to our own exemplary case. PubMed/MEDLINE was searched using the terms “hemangioblastoma,” “extradural,” “spinal,” and “nerve root.” Demographical variables of age, gender, concomitant presence of von Hippel–Lindau (VHL) disease; spinal imaging and/or intraoperative findings for tumor location were surveyed from retrieved articles. There are 38 patients with purely extradural spinal nerve root hemangioblastoma. The median age is 45 years (range = 24–72 years). Female:male ratio is 0.6. Spinal levels for purely extradural spinal nerve root hemangioblastomas, in order of decreasing frequency, are thoracic (48.6%), cervical (13.5%), lumbar (13.5%), lumbosacral (10.8%), sacral (8.1%), and thoracolumbar (5.4%). Concomitant presence of VHL disease is 45%. Purely extradural spinal nerve root hemangioblastomas are very rare and can be confused with other more common extradural spinal cord tumors. Concomitant presence of VHL disease is observed in less than half of the patients with purely extradural spinal nerve root hemangioblastomas. Surgery is the first-line treatment in these tumors.

Updates in Benign Lesions of the Genitourinary Tract

The genitourinary tract is a common site for new cancer diagnosis, particularly for men. Therefore, cancer-containing specimens are very common in surgical pathology practice. However, many benign neoplasms and nonneoplastic, reactive, and inflammatory processes in the genitourinary tract may mimic or cause differential diagnostic challenges with malignancies. Emerging clinicopathologic, immunohistochemical, and molecular characteristics have shed light on the pathogenesis and differential diagnosis of these lesions. This review addresses differential diagnostic challenges related to benign genitourinary tract lesions in the kidney, urinary bladder, prostate, and testis, with emphasis on recent advances in knowledge and areas most common in diagnostic practice.

Evaluation of PAX8 Expression and Its Potential Diagnostic and Prognostic Value in Renal and Extra-Renal Ewing Sarcomas/PNETs

PAX8 is a transcription factor involved in the regulation of organogenesis of the thyroid gland, kidney, and Müllerian system. It is commonly expressed in epithelial tumors of thyroid and parathyroid glands, kidney, thymus, and female genital tract. PAX8 is increasingly used in the establishment of tissue of origin in carcinomas and has recently been identified in a subset of small blue round cell tumors including Ewing sarcomas/PNETs. However, it is unclear if this association in ES/PNETs is due to renal origin or is PNET specific. In this study we investigated the PAX8 staining pattern of primary renal and extra-renal ES/PNETs to explore its potential diagnostic and prognostic role. A tissue microarray (TMA) of 22 cases of extra-renal Ewing/PNETs and two separate cases of primary renal PNET whole slide sections were immunohistochemically stained with rabbit polyclonal PAX8 antibody. PAX8 was positive in 2 of 2 primary renal PNETs and in 14 (64 %) cases of the extra renal PNETs. The association between PAX8 immunoreactivity and Ewing/PNET was identified in both primary renal and extra-renal Ewing/PNETs for the first time. Further studies are warranted to verify these findings and to shed light in the tumorigenesis of Ewing/PNET. However, PAX8 is not useful in establishing a diagnosis of Ewing/PNET due to its presence in different tumors like carcinomas, lymphomas and sarcomas. PAX8 does not seem to have prognostic value.

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.

Primary gastric hemangioblastoma: report of a case

Capillary hemangioblastoma (CHB) is a benign, highly vascularized tumor that generally occurs in central nervous system either in the setting of von Hippel-Lindau (VHL) disease or, more often, as a solitary sporadic lesion that is increasingly recognized in extraneural sites. We present the case of a 18 year-old man with abdominal pain, nausea and hematemesis, the endoscopy showed polypoid tumor bleeding of 5 cm in gastric antrum. The patients had not signs of VHL disease and was subjected to subtotal gastrectomy and referred to our institution. To our knowledge this is the first reported case of CHB occurring in stomach.

Expression and diagnostic implications of carbonic anhydrase IX in several tumours with predominantly clear cell morphology

AIMS

High expression of carbonic anhydrase IX (CA IX) has been reported in clear cell renal cell carcinoma (ccRCC); few studies have reported CA IX expression in other tumours with predominantly clear cell morphology. The aim of study was to examine the expression and diagnostic implications of CA IX in these latter tumours.

METHODS AND RESULTS

An immunohistochemical study was performed of 159 tumours with predominantly clear cell morphology. The results showed that, in addition to primary (25/25) and metastatic (10/11) ccRCC, CA IX was also expressed in breast (2/2), pulmonary (3/5) and hepatic (1/4) clear cell carcinoma, urothelial carcinoma with clear cell change (3/6), clear cell meningioma (4/6) and ependymoma (2/3), haemangioblastoma (10/10), and clear cell hidradenoma (5/6). However, while strong and diffuse positivity for CA IX was observed in ccRCC, clear cell breast carcinoma, haemangioblastoma, and clear cell hidradenoma, the other cases showed predominantly focal positivity for CA IX. In particular, CA IX staining was often seen at the periphery of necrotic areas.

CONCLUSIONS

Our results indicate that strong and diffuse CA IX expression may be useful for differentiating ccRCC from several clear cell tumours, with the exception of clear cell breast carcinoma, haemangioblastoma, and clear cell hidradenoma.