DOI: 10.33962/roneuro-2021-047 Intracranial myopericitoma. A case report of a rare tumour in a rare location in an AIDS patient Branko Đurović, Danilo Radulović, Miloš Joković, Irena Cvrkota, Marko Đurović, Nemanja Jovanović, Vuk Aleksić Romanian Neurosurgery (2021) XXXV (3): pp. 281-284 DOI: 10.33962/roneuro-2021-047 www.journals.lapub.co.uk/index.php/roneurosurgery Intracranial myopericitoma. A case report of a rare tumour in a rare location in an AIDS patient Branko Đurović1, Danilo Radulović1, Miloš Joković1, Irena Cvrkota1, Marko Đurović1, Nemanja Jovanović1, Vuk Aleksić1,2 1 Neurosurgery Clinic, Clinical Centre of Serbia, Belgrade, SERBIA 2 Department of Neurosurgery, Clinical Hospital Centre Zemun, Belgrade, SERBIA ABSTRACT Myopericytoma is a benign, soft tissue tumor probably derived from perivascular myoid cells. They are usually found in subcutaneous tissues in the extremities. Intracranial localization of myopericitoma is exceedingly uncommon. We report a 43 years old male patient with incidentally found myopericitoma of the posterior fossa. Patient was operated and tumor was completely removed. Patient was subsequently diagnosed with acquired immunodeficiency syndrome due to human immunodeficiency virus infection. One year after operation tumor showed no signs of recurrence, but patient developed progressive symptoms of AIDS and started highly active antiretroviral therapy (HAART). Connection of intracranial myopericitoma appearance and HIV/AIDS has been reported before, but clear connection is yet to be elucidated. INTRODUCTION Myopericytoma represents a rare benign lesion most frequently found in soft tissue. However, it may arise in any other location. Clinical, neurological and radiological features are unspecific with symptoms arising due to compression of surrounding structures. Surgical resection is the treatment of choice with excellent prognosis. Pathology examination provides the definite diagnosis, but the differential diagnosis is wide. Intracranial location is exceedingly uncommon, and we found only several case reports described in the literature2,7. Connection of intracranial myopericitoma appearance and human immunodeficiency virus infection has been reported before, but causal connection is yet to be elucidated1. We present a case of a 43 years old male with incidentally found myopericitoma of the posterior fossa. One year after the operation patient was diagnosed with acquired immunodeficiency syndrome due to human immunodeficiency virus infection. Keywords AIDS/HIV, myopericitoma, intracranial tumour Corresponding author: Vuk Aleksić Department of Neurosurgery, Clinical Hospital Centre Zemun, Belgrade, Serbia aleksicvuk@hotmail.com Copyright and usage. This is an Open Access article, distributed under the terms of the Creative Commons Attribution Non–Commercial No Derivatives License (https://creativecommons .org/licenses/by-nc-nd/4.0/) which permits non- commercial re-use, distribution, and reproduction in any medium, provided the original work is unaltered and is properly cited. The written permission of the Romanian Society of Neurosurgery must be obtained for commercial re-use or in order to create a derivative work. ISSN online 2344-4959 © Romanian Society of Neurosurgery First published September 2021 by London Academic Publishing www.lapub.co.uk http://www.lapub.co.uk/ 282 Branko Đurović, Danilo Radulović, Miloš Joković et al. CASE REPORT We present a case of a 43 years old male gynecologist who was first examined 6 years ago because of typical migraine headaches, when brain computed tomography (CT) showed small dural based extra axial hyperdense lesion in the posterior region of foramen magnum without significant compressive effect, which was confirmed with brain magnetic resonance imaging (MRI). The patient was motivated for further intermittent follow-up and consecutive MRI showed no signs of lesion expansion and patient remain neurologically intact without symptoms and any complains for almost 6 years. However, patient skipped the last two fallow- ups since he was clinically suspected for COVID-19 infectious disease, although three consecutive PCR tests were negative. Shortly after resolution of respiratory symptoms patient abruptly developed ataxia and gait disturbance with severe neck pain after which he was admitted in our emergency department and brain CT scan showed significant enlargement of extra axial lesion in the posterior cranial fossa with signs of cerebellar and fourth ventricle compression, but without signs of hemorrhage nor hydrocephalus (Figure 1). Figure 1. First brain CT after development of signs and symptoms of cerebellar dysfunction, showing tumor in the cerebellum. Patient was transferred to Neurosurgical clinic of Clinical center of Serbia. At department admission he presented with cerebellar symptomatology including ataxia, asthenia and astasia-abasia complex without muscle weakness accept of mild bilateral thigh flexors weakness. Also, global hyperreflexia with atypical plantar reflex bilaterally was noted. His past medical history was insignificant. Brain MRI showed large intradural extra-axial ovoid shaped tumor measuring 36 x 31 x 33 mm in diameter (LL x AP x CC) located at the posterior midline aspect of foramen magnum and with signs of cerebellar and fourth ventricle compression (Figure 2). Patient was prepared for neurosurgical intervention, and MRI angiography was performed to visualize V3 and V4 segments of vertebral arteries, and fortunately they were distant from the tumor. Figure 2. Brain MRI showing tumor in the posterior aspect of foramen magnum: (A) axial plane, (B) sagittal plane. On the day of surgery, extremely rare situation occurred. Namely, four consecutive transfusion cross-matching blood tests using activated Papain showed positive inter-reaction. However, after our Blood Transfusion Institute provided enough units of blood, we proceeded with intervention, and the patient was operated in the sitting position. The skin was incised on the midline from the occipital protuberance down to the upper cervical region. The midline plane was opened between the posterior muscles, up to the occipital protuberance and down to the spinous process of C2. Bone opening was performed using a drill and Kerrison rongeurs. We decided to perform small right unilateral approach instead of large medial bone opening, since we wanted to avoid occipital sinus injury. Posterior margin of foramen magnum has been also removed. The dura was incised in a Y-shaped fashion and retracted with stitches. After dura opening and retraction of right cerebellar hemisphere, a tumor with insertion on the midline portion of dura was brought into view. The plan was to be perform tumor debulking with the ultrasound aspirator, however since tumor was highly vascularized, we decided to coagulate and liberate dural insertion, after which the tumor was removed in one piece (Figure 3). Operation and early postoperative period were uneventful. Blood loss during operation was minimal, and there was no need for a blood transfusion. Patient recovered well, and preoperative cerebellar symptomatology was less 283 Intracranial myopericitoma pronounced. Control brain CT showed complete tumor removal. Patient was discharged on the 4th postoperative day. The conjugation of morphological, histopathological and immunohistochemical studies allowed the final diagnosis of intracranial myopericytoma. After 6 months patient was without symptoms, and control brain CT showed no signs of tumor recurrence. However, one year from operation patient suffered rapid weight loss, several episodes of recurring fever and profuse night sweats with extreme and unexplained profound fatigue. After investigations patient was diagnosed with acquired immunodeficiency syndrome due to human immunodeficiency virus (HIV) infection. Patient recently started highly active antiretroviral therapy (HAART). Figure 3. (A) Intraoperative image showing right unilateral approach during dura opening phase, (B) tumor after removal. DISCUSSION Myopericytoma is a benign tumor originating from the myoid perivascular cells6. It is often diagnosed in middle-aged patients, and most commonly arises in subcutaneous tissue of distal extremities or sometimes in retroperitoneal space. Granter et al. described the first case of myopericitoma and called it perivascular myoma3. According to current nomenclature, these tumors correspond to a continuum morphological spectrum, including myofibroma, myopericitoma and glomangiopericytoma5. First case of intracranial localization of myopericytoma was described by Rousseau et al. Since then only several cases of intracranial localization have been described8. We present a case of an intracranial myopericitoma with even more rare localization in the posterior cranial fossa. To our knowledge this is the second case of myopericitoma with posterior fossa localization. In the described cases patients had a wide range of age, with slight female predominance7. Our patient is a 43 years old male patient. The histological findings were similar in all cases from the literature with tumor composed of large thick walls vessels with myxoid changes, lined by elliptical and oval/spindle endothelial cells7. Differential diagnoses included meningioma, solitary fibrous tumor/haemangiopericytoma and angioleiomyoma. However, in all cases, as well as in our patient, immunohistochemical studies confirmed diagnosis of myopericytoma. Regarding tumor origin, some studies showed unusual molecular changes such as t(7;12)(p22;q13) and del(6)(q12q15)6. Also, some authors postulate a probable relation between Epstein-Barr infection in AIDS patients and myopericytoma development1,4. Our patient was probably HIV positive many years before operation, and AIDS symptoms appeared soon after intracranial surgery. Although reports on this peculiar association have been described in the literature, more data are needed to clearly show a connection between these entities. Intracranial myopericytoma is a low-grade slow growing tumor, with excellent overall survival. In all cases described in the literature only one patient died and it was due to other cause7. One year after the operation, our patient is without neurological symptoms and without signs of tumor recurrence. However, his general condition is worsening due to AIDS. In conclusion, intracranial myopericytoma is a rare benign neoplasm, successfully treated by surgery and with excellent follow-up. Connection of intracranial myopericitoma appearance and HIV/AIDS is yet to be elucidated. REFERENCES 1. Calderaro J, Polivka M, Gallien S, Bertheau P, Thiebault JB, Molina JM, Gray F. Multifocal Epstein Barr virus (EBV)- associated myopericytoma in a patient with AIDS. 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