Selective localization of gamma-enolase in stromal cells of cerebellar hemangioblastomas

Hemangioblastomas of the Posterior Cranial Fossa in Adults: Demographics, Clinical, Morphologic, Pathologic, Surgical Features, and Outcomes. A Systematic Review

BACKGROUND

Posterior cranial fossa (PCF) hemangioblastomas are benign, highly vascularized, and well-differentiated tumors with well-described histopathologic features. Although relatively rare, this tumor is the most prevalent primary tumor of the cerebellum in adults.

OBJECTIVE

Because the demographics of patients with such a tumor (as well as the clinical, morphologic, pathologic, surgical features, and outcomes) are not fully understood, we systematized characteristic patient and tumor features.

METHODS

We undertook a systematic review of the English-language literature in PubMed for PCF hemangioblastomas in adults published in the past 31 years. We analyzed geographic distribution and year of publication of articles; demographic data of patients; presenting symptoms and clinical signs; tumor location and morphology; histopathologic features, extent of tumor resection, perioperative blood loss, and postoperative complications; length of hospital stay; and outcomes.

RESULTS

We reviewed 207 articles describing 1759 infratentorial hemangioblastomas in a cohort of 1515 adult patients. We found female predominance in patients with Von Hippel-Lindau disease (VHLD) compared with male predominance in the general patient group. Symptoms of intracranial hypertension were more common in the VHLD group compared with the general group of patients. The cerebellar location was more common in the VHLD group and solid (parenchymatous) tumor was the most common type. Most patients underwent total resection but rate of resection did not differ between the general and VHLD groups. Most patients had a favorable outcome.

CONCLUSIONS

The literature of adult PCF hemangioblastomas is limited and general surgical experience with such tumors is scarce because of their rarity. Rates of postoperative complications and mortality remain higher than expected. However, prognosis and surgical outcomes are generally favorable. Nevertheless, surgery of adult PCF hemangioblastomas is a demanding and challenging task.

Systemic VHL gene functions and the VHL disease

The von Hippel-Lindau tumor suppressor gene (VHL) is best known as an E3 ubiquitin ligase that negatively regulates the hypoxia inducible factor (HIF). VHL mutations are the genetic defects underlying several human diseases including polycythemia, familial VHL tumor syndrome and sporadic renal cell carcinoma. VHL mutations can lead to cell-autonomous phenotypes in the tumor cells. However, non-tumor cell-autonomous functions of VHL have also been noted. VHL tumor-derived cytokines can promote inflammation and induce mobilization of endothelial progenitor cells. Up-regulation of HIF caused by VHL loss-of-function mutants, including heterozygotes, has been shown to increase the activities of hematopoietic stem cells, endothelial cells and myeloid cells. As such, systemic functions of VHL likely play important roles in the development of VHL disease.

Immunohistochemical markers to distinguish between hemangioblastoma and metastatic clear-cell renal cell carcinoma in the brain: utility of aquaporin1 combined with cytokeratin AE1/AE3 immunostaining

Distinguishing hemangioblastomas from metastatic clear-cell renal cell carcinomas (CCRCCs) in the brain is a diagnostic challenge owing to similar clinical and morphologic presentations. Inhibin-alpha and aquaporin1 were shown as positive markers of hemangioblastoma, but are not totally reliable distinguishing hemangioblastoma from metastatic CCRCC. This study shows that the diagnosis can be achieved using a combination of markers. To identify the panel of markers useful for this differential, 67 hemangioblastomas and 34 metastatic CCRCCs were analyzed using a panel of antibodies including aquaporin1, inhibin-alpha, D2-40, cytokeratin AE1/AE3, epithelial membrane antigen, and CD10. The study confirms the usefulness of aquaporin1 (97% sensitivity, 83% specificity) and inhibin-alpha (88% sensitivity, 79% specificity) as positive markers of hemangioblastoma and shows that aquaporin1 is a superior positive marker versus inhibin-alpha for the differential. Positivity of tumor cells with cytokeratin AE1/AE3 is the signature of a metastatic CCRCC (100% specificity, 88% sensitivity) and CD10 expression as well (100% specificity, 79% sensitivity). The combined use of aquaporin1 and AE1/AE3 yields a high degree of sensitivity and specificity to differentiate between hemangioblastoma and metastatic CCRCC. All tumors but one aquaporin1 positive and cytokeratin AE1/AE3 negative (65/66) correspond to hemangioblastomas (97% sensitivity, 97% specificity, 98.5% diagnostic positive predictive value). Tumors with the opposite profile, aquaporin1 negative, and cytokeratin AE1/AE3 positive, (25/25), correspond to metastatic CCRCC (74% sensitivity, 100% specificity, 100% diagnostic positive predictive value). In summary, aquaporin1 is the most sensitive positive marker of hemangioblastoma. Despite its moderate specificity, when used in combination with epithelial marker AE1/AE3, it allowed to reliably distinguish hemangioblastoma from metastatic CCRCC.

Suprasellar haemangioblastoma. Report of two cases and review of the literature

We report 2 patients with suprasellar haemangioblastoma (HBL). The first, a 54-year-old man, presented with headache and gradually worsening bilateral visual field defects that had progressed to complete blindness on the right side. Computed tomography (CT) and magnetic resonance imaging (MRI) of the brain demonstrated a suprasellar mass. The mass was removed through a pterional craniotomy. The postoperative course was uneventful. He had no stigmata of von Hippel-Lindau (VHL) disease. After 5 years follow-up, vision in the left eye is normal but the right eye remains blind and MRI reveals no recurrence. The second, a 38-year-old man presented with a 2-month history of severe headaches and complete visual loss in the left eye. He had had surgery for excision of a cerebellar HBL, 5 years prior to this presentation. CT and MRI revealed a residual mass in the posterior fossa and a new suprasellar mass. He underwent craniotomy and subtotal excision of the suprasellar tumour. The histological diagnosis was HBL in both patients. HBL in the sellar and suprasellar region are rare and may be sporadic or occur in association with VHL disease. The literature is reviewed and diagnosis and treatment options discussed.

Activation of hypoxia-inducible factor-1 in bacillary angiomatosis: evidence for a role of hypoxia-inducible factor-1 in bacterial infections

BACKGROUND

Bartonella species are the only known bacterial pathogens causing vasculoproliferative disorders in humans (bacillary angiomatosis [BA]). Cellular and bacterial pathogenetic mechanisms underlying the induction of BA are largely unknown.

METHODS AND RESULTS

Activation of hypoxia-inducible factor-1 (HIF-1), the key transcription factor involved in angiogenesis, was detected in Bartonella henselae-infected host cells in vitro by immunofluorescence, Western blotting, electrophoretic mobility shift, and reporter gene assays and by immunohistochemistry in BA tissue lesions in vivo. Gene microarray analysis revealed that a B henselae infection resulted in the activation of genes typical for the cellular response to hypoxia. HIF-1 was essential for B henselae-induced expression of vascular endothelial growth factor as shown by inhibition with the use of HIF-1-specific short-interfering RNA. Moreover, infection with B henselae resulted in increased oxygen consumption, cellular hypoxia, and decreased ATP levels in host cells. Infection with a pilus-negative variant of B henselae did not lead to cellular hypoxia or activation of HIF-1 or vascular endothelial growth factor secretion, suggesting a crucial role of this bacterial surface protein in the angiogenic reprogramming of the host cells.

CONCLUSIONS

B henselae induces a proangiogenic host cell response via HIF-1. Our data provide for the first time evidence that HIF-1 may play a role in bacterial infections.

Loss of heterozygosity reveals non-VHL allelic loss in hemangioblastomas at 22q13

Hemangioblastomas (HBs) are low-grade (World Health Organization grade I/IV) central nervous system (CNS) tumors that frequently contain VHL (3p26) mutations. They occur sporadically and in von Hippel Lindau (VHL) disease. Encoded pVHL aids degradation of hypoxia-inducible factors (HIFs) in the presence of normal oxygen levels. HBs provide an in vivo view of HIF effects within a CNS tumor. Typically, HBs are cystic tumors containing a mural nodule formed by noninvasive, vacuolated stromal cells that are embedded in a network of capillaries. Nine HBs, consecutively resected from 8 patients at our institution during a recent 2-year time span, were evaluated for additional losses of tumor suppressor genes. Non-VHL microsatellites studied for loss of heterozygosity (LOH) are near tumor suppressor genes lost in gliomas, pituitary adenomas, several CNS tumors on 22q, neurofibromatosis 1, and colon carcinomas (13, 2, 2, 1, and 2 markers for each, respectively). LOH in the region of 3p21.3-3p26.3 occurred in 3 of 8 HBs informative for at least 1 marker (D3S1539, D3S2303, or D3S2373). By using 2 markers (D22S417 and D22S532) for 22q13.2, LOH was found in 5 of 8 informative HBs. All 3 HBs with allelic losses near VHL also showed LOH at 22q13.2. No consistent losses were found with markers for 1p34, LMYC, 5q21, 5q32, 9p21, 10q23, 17p13, and 19q13. LOH for the 22q13.2 region in HBs suggests that the loss of another tumor suppressor gene is involved in the pathogenesis of HBs in addition to VHL. Absence of LOH for glioma markers is consistent with the low-grade behavior of HBs.

Inhibin alpha distinguishes hemangioblastoma from clear cell renal cell carcinoma

Inhibin alpha subunit (inhibin A) expression in hemangioblastomas has not been previously reported in the literature. We analyzed the expression of inhibin A in 25 hemangioblastomas from 22 patients. Eleven cases were from 8 patients with von Hippel-Lindau disease, and these tumors were multicentric and/or recurrent. The remaining 14 cases from 14 patients were sporadic. The male-to-female ratio was 8:3, and the age at presentation ranged from 19 to 78 years (mean 35 years; median 45 years). Eighteen tumors were located in the cerebellum/posterior fossa, 1 in the medulla, 1 in the occipital lobe, and 5 in the spinal cord. Four metastatic renal cell carcinomas in brain, 10 renal cell carcinomas from 8 patients with von Hippel-Lindau disease, and 5 sporadic clear cell renal cell carcinomas were also included. Two patients with von Hippel-Lindau disease had both renal cell carcinoma and hemangioblastoma. The stromal cells of all 25 cases of hemangioblastoma expressed inhibin A. Strong, moderate, and weak cytoplasmic immunoreactivity was noted in 17, 5, and 3 cases, respectively. In contrast, none of the 19 renal cell carcinomas, primary as well as metastatic, expressed inhibin A. There was no difference in the inhibin A staining pattern between the sporadic hemangioblastoma and those associated with VHL. These findings demonstrate inhibin A to be a useful marker in distinguishing hemangioblastoma from metastatic clear cell renal cell carcinoma. While the diagnostic importance is evident, the pathophysiology of inhibin A expression by the stromal cells of hemangioblastoma remains unknown and further investigation is required.

Transthyretin and transferrin in hemangioblastoma stromal cells

Hemangioblastoma, a rare benign tumor of the CNS, consists of two main components: capillaries and stromal cells. Despite many efforts, the histogenesis of stromal cells is still unknown. We took a new approach to clarify the origin of stromal cells using immunohistochemical methods. Paraffin-embedded tissue of 24 surgically removed hemangioblastomas of the CNS was examined with antibodies against transthyretin, transferrin, vimentin, NSE, protein S-100, CK 8, KL-1, EMA, CD34, factor VIII rAg, and collagen IV. Stromal cells showed a positive reaction with anti-transthyretin in 12 of 24 hemangioblastomas, a positive reaction with anti-transferrrin, to a different extent, in 13 of 24 cases, and many stromal cells expressed basal membrane collagen IV on the cell surface in 19 of 24 cases. The expression of transthyretin and transferrin in stromal cells of hemangioblastomas is reported for the first time, thus providing an antigenic profile of hemangioblastoma stromal cells that is very similar to that of immature choroid plexus epithelium. These findings support the notion that hemangioblastoma stromal cells may originate from the embryonal plexus epithelium. We discuss our results with special regard to stromal cell histogenesis, including a review of the literature.

Retroperitoneal peripheral hemangioblastoma: a case report and review of the literature

Central nervous system hemangioblastomas are uncommon tumors of controversial etiology that are usually found in the posterior fossa of the cranial cavity, retina, and spinal cord. Peripheral involvement is rare; only isolated case reports have been identified. We report an unusual case of hemangioblastoma involving the retroperitoneum. A 47-year-old African-American man presented with polycythemia on routine laboratory testing. Computed tomography revealed a large retroperitoneal mass near the pancreas, in a left suprarenal location, without adrenal involvement and without attachment to a nerve. Although hemangioblastoma may be associated with the von Hippel-Lindau syndrome, this patient did not have any of the stigmata of this disease. The histologic features included a highly vascular tumor with cellular areas composed of plump, pleomorphic spindled and epithelioid (stromal) cells with variable cytoplasmic lipid vacuoles and hypocellular areas with inflammatory cells and collagenous fibrils. Immunohistochemical staining showed that the tumor (stromal) cells were positive for vimentin, calponin, S-100 protein, neuron-specific enolase, and CD57 and negative for glial fibrillary acidic protein, cytokeratins, epithelial membrane antigen, CD34, HMB-45, desmin, and the actins. These morphologic and immunohistochemical findings are consistent with hemangioblastoma. To our knowledge this is the first reported case of a hemangioblastoma in this location. Based on this case we conclude that hemangioblastoma may occur in the retroperitoneum and outside of the central nervous system in a patient without von Hippel-Lindau syndrome. The immunoprofile of this case suggests that hemangioblastomas are mesenchymal neoplasms exhibiting both neural and myofibroblastic differentiation.

Angiogenic histogenesis of stromal cells in hemangioblastoma: ultrastructural and immunohistochemical study

Controversy regarding the origin of characteristic stromal cells (SC) is responsible for the placement of hemangioblastoma as a single entity in the category of "tumors of uncertain histogenesis" in the current WHO classification of brain tumors. This subclassification of hemangioblastoma is, to a large extent, a consequence of a remarkable antigenic heterogeneity of SC demonstrated in many, often contradictory immunohistochemical studies. In contrast, most of the electron microscopic studies demonstrated a number of features indicating angiogenic nature of SC and, therefore, hemangioblastoma. This study reevaluated the histogenesis of SC, applying immunohistochemistry as well as electron microscopy and immunoelectron microscopy. Immunohistochemical studies confirmed most of the previous results indicating a very frequent expression of vimentin, S-100 protein, neuron-specific enolase, and cytokeratins. SC were less commonly immunoreactive for desmin, factor XIIIa, and Ricinus communis lectin receptors, and only occasionally for factor VIII and Ulex europeus lectin. They were negative for other markers of endothelial, neuronal, glial, neuroendocrine, and smooth muscle differentiation. Approximately 1% of SC showed Ki67 immunoreactivity, indicating their slight proliferative activity, consistent with the benign nature of the tumor. In contrast to the inconclusive results of the immunohistochemistry, electron microscopy demonstrated a clear relationship of SC to endothelial cells, smooth muscle cells, and pericytes. Occasional SC were found within the vascular lumina. SC often showed intracellular caveolae consistent with the formation of early capillary lumina. Moreover, occasional SC contained small Weibel-Palade bodies positive for factor VIII in immunoelectron microscopy. SC represent a heterogeneous population of abnormally differentiating mesenchymal cells of angiogenic lineage, with some morphological features of endothelium, pericytes, and smooth muscle cells. Occurrence of SC in hemangioblastoma could be related to a limited ability of angioformative stromal cells to develop an architecture of capillary lumina integrated with the vascular network of the tumor. Hemangioblastoma should be reclassified and included together with other vascular tumors of the central nervous system.

Desmoplastic cerebral astrocytoma of infancy. Light microscopy, immunocytochemistry, and ultrastructure

The first detailed ultrastructural study of a superficial desmoplastic cerebral astrocytoma of infancy is reported. This is a neoplasm which mimics a mesenchymal tumor, originally described in 1984 under the name of "superficial cerebral astrocytoma attached to dura." This tumor, which is believed to have a good prognosis, was resected from the frontoparietal region of a 6.5-month-old girl, in whom it had presented as a large densely enhancing vascular and cystic mass. The ultrastructure of the tumor appeared to be distinctive, characterized by the absence of neuronal elements, and the presence of large amounts of redundant and sometimes extensively duplicated basal laminal material and collagen between nonpleomorphic and nonlipidized astrocytes, corresponding to the reticulin fibers seen by light microscopic analysis between the S-100 protein and glial fibrillary acidic protein (GFAP)-positive cells. The features of the tumor, its differential diagnosis, and its relationship to other pediatric supratentorial tumors are discussed.

Diagnostic markers in human neurooncology. A progress report

In this progress report, some of the most commonly used antibodies are discussed in regard to their immunohistochemical application to human neurooncology. The importance of determining the spectrum of antibody immunoreactivity in a wide panel of normal, reactive, and neoplastic tissues is stressed. in atypical and aberrant cases, immunopositivity needs to be interpreted with caution and in the context of all other available data. The demonstration of a well-characterized, cell type-specific marker in a tumor reflects not so much its cytogenesis as its differentiation potential and its capacity for metaplasia. The relation of an abnormal or aberrant expression of antigenic determinants to the process of neoplasia raises a number of intriguing questions to which research in the next few years will likely provide answers.

Haemangioblastoma. An immunohistochemical study of ten cases

Ten cases of cerebellar haemangioblastoma were studied using the immunoperoxidase technique for glial fibrillary acidic protein (GFAP), Factor VIII-related antigen (F8RA), Ulex europeus agglutinin 1 (UEA-1), S-100 protein, neurone-specific enolase (NSE), leucocyte common antigen, synaptophysin, chromogranin and eight polypeptide hormones (bombesin, pancreatic polypeptide, somatostatin, thyroglobulin, calcitonin, glucagon, insulin and gastrin). GFAP and S-100 were demonstrated at the periphery of all tumours and in small groups of cells in the centre of four cases. Most of these cells had the morphology of reactive astrocytes but some had the appearance of stromal cells. In general stromal cells gave negative results. F8RA and UEA-1 stained the endothelial cells in each case but there was no stromal cell reactivity. NSE was present in the stromal cell component of all tumours. There was no staining for synaptophysin, for chromogranin, or any of the polypeptide hormones. It therefore appears that some haemangioblastomas contain an admixed non-neoplastic astrocytic element. NSE, F8RA and UEA-1 staining demonstrates that the endothelial and stromal cell parts of the tumour are antigenically distinct. Recent reports of polypeptide hormone expression cannot be confirmed and it is therefore unlikely that stromal cells originate from primitive peptidergic neurones.

Immunohistochemical characteristics of haemangiopericytic meningiomas: comparison with typical meningiomas, haemangioblastomas and haemangiopericytomas from extracranial sites

The relationship between malignant vascular meningeal tumours and typical meningiomas remains controversial, despite the need for accurate diagnostic distinction between the two, and some forms of vascular meningioma may be more closely allied to haemangioblastomas or extracranial haemangiopericytomas than to true meningiomas. In order to try to clarify the diagnostic characteristics and origins of the entity known as haemangiopericytic meningioma, 10 histologically typical cases were stained by the immunoperoxidase technique with a panel of seven antibodies. The results were compared with those obtained from typical and angiomatous meningiomas, haemangioblastomas and haemangiopericytomas from extracranial sites. Both the haemangiopericytic meningiomas and the extracranial haemangiopericytomas showed a similar staining pattern, which differed from that of the typical and angiomatous meningiomas in the strikingly focal nature of the vimentin staining and the lack of reactivity with antibodies to epithelial elements. The haemangioblastomas were less consistent in their individual staining characteristics, but had a quite different overall pattern from all the other tumour types. It is, therefore, suggested that so-called haemangiopericytic meningiomas are in fact primary haemangiopericytomas of the meninges, antigenically distinct from true meningiomas and displaying a malignant potential appropriate to haemangiopericytomas arising in any other sites.