1. Spinal Hemangiopericytoma: a Rare Ocurrence Antônio Santos de Araújo Júnior 1 ; Arnaldo Salvestrini Jr 1 ; Pedro Alberto Arlant 1 ; Orlando Parisi 2 ; Mirella Martins Fazzito 3 ; Conrado Furtado de Albuquerque Cavalcanti 4 ; Hae Won Lee 4 ; Ricardo Antenor de Souza e Souza 5 ; Luiz Heraldo Arouche da Câmara Lopes 5 1. Neurosurgeon from Sírio Libanês Hospital, São Paulo, Brazil; 2. Head and Neck Surgeon from Sírio Libanês Hospital, São Paulo, Brazil; 3. Neurologist from Sírio Libanês Hospital, São Paulo, Brazil; 4. Radiologist from Sírio Libanês Hospital, São Paulo, Brazil; 5. Neuropathologist from Sírio Libanês Hospital, São Paulo, Brazil Introduction: Most hemangiopericytomas (HPC) are located in the musculoskeletal system and the skin, while the location in the central nervous system (CNS) is rare. The latter represents 2 to 4% in large series of meningeal tumors, thus accounting for less than 1% of all CNS tumors. CNS hemangiopericytomas (HPC), by definition, are highly cellular and vascularized mesenchymal tumour exhibiting a characteristic monotonous low-power appearance and a well-developed, variably thick-walled, branching “staghorn” vasculature; almost always attached to the dura and having a high tendency to locally recur and to metastasize outside the CNS. On radiographic films, HPC appear as a well-demarcated, lytic lesion of adjacent bone, without hyperostosis, a typical feature of meningiomas. Unlike meningiomas, HPC typically lack calcification. On macroscopic examination, meningeal HPC is a solid, well- demarcated tumor, with a tendency to bleed during removal, sometimes profusely. The tumor is usually globoid, slightly lobulated, with firm consistency, grayish to red-brown colored. Spinal hemangiopericytomas Spinal HPCs respond to approximately 8% of all HPC, tend to occur isolated and attached to spinal dura-mater, and usually present a good surgical cleavage between the tumor and the dura. Spinal HPCs mostly involve the extradural bony structures. Primary intradural HPC has only been reported in 10 cases, all of which occurred in the extramedullary region. Case report: We describe a 66-year-old male patient harboring a chronic onset of right leg distal paresis, and instable gait. On neurological examination, he presented with right leg monoparesis, intact pain and light touch sensitivity, loss of unconscious proprioception, with deep tendon patellar hyperreflexia, and abnormal Romberg´s test with sensory ataxia. The patient was promptly submitted to cervicothoracic MRI, showing a huge paravertebral mass, ranging from C6 to T3 level, with homogeneous Gadolinium enhancement, and marked spinal cord compression at T1 level (Figure 1-2). Patient was then submitted to surgery, via a posterior approach, indentifying a huge red-brown firm mass, highly vascular, with profuse bleeding. T1 laminectomy was performed in order to dissect the tumor from the dura-mater, with clear cleavage plane. Total gross removal was accomplished, with “in-block” resection (Figure 3), preserving adjacent tissues and the neurological function, as shown by somatosensitive evoked potential. Histopathological examination and immunohistochemistry essay were performed confirming the diagnosis of HPC (Figure 4). Postoperatively, patient was symptom-free, with normal gait, accomplishing normal daily activities within 2 weeks. Conclusion: HPCs tend to grow faster than anaplastic meningiomas, instead the same median Ki-67 labelling index of 5% (1.2-39%). The local recurrence occurs in approximately 85 to 91% of cases after 15 years. Eventually meningeal HPCs can metastasize to the bones, lungs and liver. Overall, in a series of 28 patients harboring intracranial HPCs, the probability of tumor-related death was 61% at 15 years. References 1.Araújo Jr AS, Salvestrini Jr A, Arlant PA, et al. Spinal hemangiopericytoma: a rare occurrence. Neurosurgery Quarterly, May 2012; 22:84-87. 2. Mekni A, Kourda J, Chelly I, et al. Hemangiopericytoma in the central nervous system. A study of eight cases. Neurochirurgie 2008; 54(1):15-20. 3. Giannini C, Rushing EJ, Hainfellner JA. Haemangiopericytoma. In:Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, ed. WHO Classification of tumours of the central nervous system. 3rd ed. Lyon, FR. IARC; 2007: 178-180. Figure 1. Sagital cervicothoracic T2-weighted (A and B) and post-contrast T2- weighted (C) MRI. (A) Paravertebral cervico thoracic mass, with lobulated appearance; (B) At T1 level, tumoral spinal cord compression without dural invasion, intratumoral heterogeneous signal; (C) Post-Gadolinium, homogeneous tumoral enhancement. Figure 2. Axial cervicothoracic T2-weighted MRI (A and B) and post-contrast T1- weighted MRI (C). (A) Paravertebral mass with lytic lesion from right T1 lamina and spinous process, dislocating the spinal cord to anterior left position; (B) At T1 level, marked spinal cord compression by heterogeneous signal lesion; (C) Post- Gadolinium, homogeneous tumoral enhancement. AB C Figure 3. Total gross ‘in block’ resection, measuring almost 10 cm. AB C A B C D E Figure 4. (A) HE stain, 40x magnification, monomorphous tumor composed of closed packed, randomly oriented tumor cells; (B) 100x magnification, highly cellular tumor with staghorn-type vessels, little intervening fibrosis and marked extracellular matrix, and with lipomatous deposition; (C) 400x, closed packed monomorphous cells with lipomatous deposition; (D) Immunohistochemistry essay, 400x, patchy pattern immunoreactivity for CD34; (E) Immunoreactivity for CD31, 400x, patchy pattern.