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Journal of Cancer Research and Therapeutics, Vol. 6, No. 4, October-December, 2010, pp. 560-563 Case Report Cystic angiomatous meningioma in the cerebellopontine angle mimicking hemangioblastoma Prabal Deb1, Hirdesh Sahni2, Harjinder Singh Bhatoe3 1 Department of Pathology, Armed Forces Medical College, Pune, India Correspondence Address: Prabal Deb, Associate Professor and Neuropathologist, Department of Pathology, Armed Forces Medical College, Pune, India, debprabal@indiatimes.com Code Number: cr10138 PMID: 21358102 DOI: 10.4103/0973-1482.77074 Abstract We hereby report an extremely unusual case of cystic angiomatous meningioma in the CPA region in a 58-year-old male patient. He presented with complaints of headache, repeated episodes of vomiting and increasing unsteadiness of gait. Neuroimaging showed a large multicystic left-sided tentorial tumor projecting into the cerebellum and CPA with contrast-enhancing peripheral solid rim. He underwent a left retromastoid craniectomy and total excision of the tumor. Histopathology revealed an angiomatous meningioma with predominant microvascular component and extensive cystic changes. Immunopositivity for epithelial membrane antigen (EMA), vimentin and S-100 protein proved vital in excluding a hemangioblastoma.Keywords: Angiomatous, cerebellopontine angle, cystic, meningioma Introduction Cystic meningiomas are uncommon tumors that have predilection for the pediatric age group, and commonly occur in the cerebral convexity and parasaggital areas. These neoplasms often mimic gliomas, metastatic malignancies, or hemangioblastomas, which are more frequently associated with a cystic morphology. [1],[2],[3] Angiomatous meningiomas are also rare and its association with cystic morphology, unlike meningothelial type, is uncommon. Most angiomatous meningiomas affect the cerebral convexity, and its occurrence in the cerebellopontine angle (CPA) is unusual. [1],[4] Encountering a meningioma with both cystic and angiomatous pattern is exceptional, and its location in the CPA region, to the best of our knowledge, has never been reported. Case Report A 58-year-old male patient presented with complaints of headache, repeated episodes of vomiting and increasing unsteadiness of gait. Clinical examination revealed left-sided cerebellar dysmetria with dysdiadochokinesia. He was normotensive and lacked any neurocutaneous marker. Routine laboratory investigations were within normal limits. Computerized tomography (CT) scan showed a cystic tumor in the left CPA, close to the tentorium. Contrast studies showed rim enhancement. There was no hydrocephalus or calcification. Magnetic resonance imaging (MRI) revealed a large multicystic left tentorial tumor measuring 5 × 4 × 3 cm with solid mural component, projecting into the left cerebellum and CPA. There was prominent enhancement of the internal septae and the eccentric solid mural component [[Figure - 1]a-c]. The transverse sinus is not infiltrated. Minimal perilesional edema is seen in the adjoining cerebellar hemisphere. A left retromastoid craniectomy with total excision of the tumor was performed. Peroperatively, dura was defined between lateral and sigmoid sinuses. On retracting the cerebellum, a firm, well defined cystic vascular tumor containing straw colored fluid was noted, which was adherent to tentorial leaf and compressing the cerebellum, which could be excised completely. Tissue was fixed in 10% neutral buffered formalin, routinely processed and paraffin embedded. Five-micron thick sections were cut and stained by hematoxylin and eosin (H and E) stain. Immunohistochemical staining was done by streptavidin-biotin immunoperoxidase technique (LSAB Kit, M/s Dakopatts, Denmark) using monoclonal antibodies to epithelial membrane antigen (EMA), vimentin (Vim), S-100 protein, and glial fibrillary acidic protein (GFAP); while proliferation index was evaluated using MIB-1 antibody staining (all antibodies were prediluted and obtained from M/s BioGenex, US). Microscopically, tumor appeared highly vascular with prominent cystic areas. Majority of the tumor was composed of small, capillary-like and thin-walled blood vessels (′microvascular pattern′). Intervening areas contained variable amount of tumor cells with vacuolated cytoplasm [[Figure - 2]a-d]. There was no increased mitosis, microvascular proliferation or necrosis. Immunopositivity of tumor cells for epithelial membrane antigen (EMA), vimentin [[Figure - 2]e, f] and S-100 protein confirmed a diagnosis of angiomatous meningioma in preference to hemangioblastoma. MIB-1 labeling index (MIB-LI) was < 1%. Post-operative recovery was largely uneventful. He was on regular follow-up for the next six months; and at last review, he was asymptomatic, ambulant, without any neurological deficit. Discussion Meningiomas comprise 15-18% of intracranial tumors in adults and 33% of all incidental intracranial neoplasms. [1] Angiomatous meningioma is an uncommon variant accounting for 2.1% of all meningiomas and having predilection for the cerebral convexity. [4] In the CPA, meningiomas account for approximately 3-13% of all neoplasms, with two large series reporting an incidence of 6.5%. [5] The most common variants are meningothelial and transitional, while angiomatous is a rarity. [5],[6] It is postulated that CPA meningiomas originate from the cells lining arachnoid villae located adjacent to intracranial veins and dural sinuses. They usually grow from areas adjacent to the sigmoid sinus, jugular foramen, torcula, or the superior and inferior petrosal sinuses. [5] Cystic meningiomas are also rare, accounting for 0.7% to 11.7% of all meningiomas. [2] These neoplasms generally affect children and have predilection for convexity and parasaggital sinus, features which were contrary to the present case. It is unusual for cystic meningiomas to either display an angiomatous component or to occur in the CPA; [7] and meningiomas in the CPA region to have both cystic and angiomatous pattern is not known. Cyst formation in meningiomas is thought to be a resultant of ischemic necrosis, cystic degeneration, intratumoral hemorrhage, trapping of CSF, peritumoral edema into cyst, active secretion by tumor cells, or due to glial reaction and transudation. [8] Cystic meningiomas have been classified by Nauta et al[9] into types 1 to 4, based on if cysts were intratumoral, peritumoral with / without tumor lining cyst wall, and cyst at the brain-tumor interface. The present case was of type 2. With the availability of CT scan and MRI, the incidence of diagnosing cystic meningioma has increased. Currently, MRI especially with gadolinium enhancement, is the preferred mode, since this is able to distinguish cyst wall invaded by tumor cells (type 2) from cyst wall composed of gliotic tissue without tumor infiltration (type 3). The presence of a nodule of a cystic lesion close to the dura, and enhancement of the adjacent dura suggests the diagnosis of a cystic meningioma. [3],[10] In general, ′true′ intratumoral cysts in association with highly vascularised meningiomas are exceedingly rare, with an incidence of around 0.2% only. [7] In the past, most cases of highly vascularized cystic meningiomas have been reported as ′angioblastic meningioma′, an obsolete term which has often included hemangioblastoma and hemangiopericytoma, apart from transitional cases between meningioma and hemangioblastoma, vascular malformation and metastasis from renal cell carcinoma. [1],[7] On histopathology, angiomatous meningioma is chararcterised by abundance of well-formed vascular channels, sinusoids or capillaries. In their series of 38 cases, Hasselblatt et al[4] noted two subtypes of angiomatous meningioma, viz. microvascular subtype (more than 50% contain vessels with diameter below 30 μ), and a macrovascular subtype. These tumors may also display microcystic change along with foamy cells (which are related to leakage of plasma lipids across thin vessel walls); in addition to solid areas with meningotheliomatous meningioma elements. In view of the cystic neoplasm on imaging, prominent microvascular pattern with foamy cells in the present case suggested the possibility of hemangioblastoma. Hemangioblastomas are benign neoplasms of uncertain histogenesis constituting 1-2% of all primary central nervous system tumors. [1] Cerebellar hemangioblastoma is the most common initial manifestation, affecting 64% of patients with von Hippel-Lindau (VHL) disease. MRI has largely replaced both angiography and CT scan. Currently gadolinium-enhanced MRI, showing a contrast-enhancing nodule with the associated cyst or syrinx, is the diagnostic method of choice. Although false-negatives may be seen with small lesions (<5 mm) and with delayed imaging, false-positive findings are rare and may be due to metastatic lesions or arachnoid cysts. [11] On gross the lesions are small nodules in the wall of a cyst. The fluid is characteristically yellow to brown, whereas the tumor is red and / or yellow depending on the vascularity and lipid content. On histopathology, large vacuolated stromal cells along with a rich capillary network characterize hemangioblastoma. The ′clear cell morphology′ of stromal cells due to numerous lipid-containing vacuoles mimics metastatic renal cell carcinoma, while the exuberant gliosis around the cyst wall may resemble pilocytic astrocytoma. [1] Since both angiomatous meningioma and hemangioblastoma are benign tumors, the need to differentiate them from therapeutic viewpoint appears irrelevant, though a confirmed diagnosis of hemangioblastoma often suggests VHL disease. Further, differentiating angiomatous meningiomas from hemangiopericytoma is imperative since the former is not associated with aggressive clinical behavior. [1],[7] References
Copyright 2010 - Journal of Cancer Research and Therapeutics The following images related to this document are available:Photo images[cr10138f2.jpg] [cr10138f1.jpg] |
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