British Journal of Neurosurgery, February 2015; 29(1): 90–91 © 2014 The Neurosurgical Foundation ISSN: 0268-8697 print / ISSN 1360-046X online DOI: 10.3109/02688697.2014.952270
SHORT REPORT
Myopericytoma of the posterior cranial fossa Catherine H. Zhang1, Harutomo Hasegawa1, Paul Johns2 & Andrew J. Martin1 1Department of Neurosurgery, Atkinson Morley Wing, St. George’s Hospital, London, UK, and 2Department of Cellular
Br J Neurosurg Downloaded from informahealthcare.com by Nyu Medical Center on 06/08/15 For personal use only.
Pathology, St. George’s Hospital, London, UK
focal concentric perivascular whorling. Nuclear atypia was modest, mitotic profiles were not identified and no necrosis or brain invasion was found. The Ki67 (proliferative) index was very low. Immunohistochemistry for epithelial membrane antigen (EMA) demonstrated a thin peripheral layer of cells at the lesion margins, in keeping with meningothelial tissue. The stroma and vessel walls were immunopositive for smooth muscle actin (SMA) and h-caldesmon, but negative for desmin (Fig. 2b). Labelling for CD34 demonstrated a layer of unremarkable endothelial lining cells, but was negative in the stromal cells. Despite the unusual location, the overall histological pattern and immunophenotype were felt to be most consistent with a myopericytoma.
Abstract Myopericytoma is a soft tissue tumour believed to be derived from perivascular myoid cells. They are typically found in subcutaneous tissues in the extremities. Intracranial myopericytomas are exceptionally rare. Here we report a man with an asymptomatic posterior fossa myopericytoma with evidence of dural infiltration. Keywords: angioleiomyoma; brain tumour; haemangiopericytoma; myopericytoma
Clinical details A 36-year-old right-handed man of South East Asian origin presented in 2006 with a left-sided Bell’s palsy. Brain MRI revealed an incidental 26 ⫻ 18 ⫻ 15 mm extra-axial, lobular, durally based mass at the right cerebellar convexity, which was hypointense on T1-weighted images, hyperintense on T2-W, and enhanced avidly with contrast. There was no mass effect or hydrocephalus. The patient had no relevant symptoms and the neurological examination was normal other than left facial weakness. The tumour was presumed to be a meningioma and was initially managed with surveillance imaging at his local hospital. It enlarged slowly and the patient was referred for elective excision seven years later, when the tumour had grown to 28 ⫻ 26 ⫻ 20 mm (Fig. 1). A standard midline posterior fossa craniotomy was performed, and a distinct plane was found between the tumour and the brain. The consistency of the tumour was soft in some parts and fibrous in others, vascular, and unusually lobulated. The tumour was attached to the dura on the cerebellar convexity, and this was detached and coagulated. The recovery from surgery was uneventful and a 6-month post-operative MRI confirmed complete resection. Histology showed a highly vascular lesion infiltrating the dura, composed of multiple blood-filled channels of varying sizes (Fig. 2a). The vascular spaces were separated by walls of variable thickness, composed of fibrous tissue and smooth muscle, surrounded by round to oval cells with
Discussion Myopericytoma was described by Granter and colleagues in 1998, as part of their reappraisal of haemangiopericytoma as a clinicopathological entity. It is part of a spectrum of tumours showing perivascular myoid differentiation, which includes myofibromas, glomangiopericytomas and angioleiomyomas. The predominant histological pattern of myopericytomas was described as the presence of round to oval cells with eosinophilic cytoplasm, arranged circumferentially in layers around vascular lumina in an ‘onion-skin’ pattern.1 Macroscopically, they are typically well-circumscribed
Fig. 1. Post-contrast MRI showing a lobulated, enhancing tumour in the posterior fossa.
Correspondence: Dr. Catherine Zhang, Department of Neurosurgery, Atkinson Morley Wing, St. George’s Hospital, Blackshaw Road, London SW17 0QT, UK. E-mail: [email protected] Received for publication 31 May 2014; accepted 3 August 2014
90
Posterior fossa myopericytoma
91
Br J Neurosurg Downloaded from informahealthcare.com by Nyu Medical Center on 06/08/15 For personal use only.
Fig. 2. Low power photomicrographs showing the main histopathological features of the lesion. (a) Routine haematoxylin and eosin (H&E)-stained section showing a well-circumscribed benign vascular tumour composed of small and large anastomosing channels, lined by unremarkable endothelial cells. (b) Immunohistochemistry for smooth muscle actin shows that the walls of the blood-filled spaces contain smooth muscle. Immunolabelling for desmin, EMA and CD34 (not shown) was negative in the stromal cells.
and unencapsulated. Clinically, they are slow-growing and usually painless, mostly found in soft tissues of the extremities, and do not recur after surgical resection. Malignant myopericytomas are rare, but have been reported to occur in the extremities, neck and mediastinum.2 Intracranial myopericytomas are extremely rare. Isolated intracranial myopericytomas have only been described in a case series of three reports by Rousseau et al.2 The cases in this series included a calcified pineal region tumour, a tumour of the orbital apex eroding the sphenoid bone, and an anterior fossa tumour. MRI characteristics were hypointense on T1, hyperintense on T2 and all enhanced with gadolinium contrast. Clinical presentations were with hydrocephalus in the first and with reduced visual acuity in the latter two cases. All three were successfully treated with surgical resection, and no recurrence was reported within 9–12 months for two patients. The other patient (pineal region tumour) died six months after surgery due to an unrelated cause. Only the anterior fossa tumour was reported to show tumour proliferation abutting the dura, but there was no evidence of infiltration. All tumours were immunopositive for SMA and vimentin, and negative for cytokeratins, EMA, CD34 antigen, desmin, and S100 protein. Multifocal myopericytomas involving the intracranial cavity in immuno-compromised patients have been reported in two patients.3 The affected sites were the cerebellopontine angle and the right frontal lobe. The Epstein-Barr virus (EBV) has been suggested as a possible aetiological factor in these cases. Both these patients did not undergo complete resection of the tumours but have survived for many years, leading Lau et al.3 to conclude that multifocal disease may suggest multicentric growth rather than metastasis.
We present the first description of an isolated intracranial myopericytoma arising in the posterior fossa, infiltrating the dura. It is possible that similar tumours were classified as haemangiopericytomas prior to the description of the myopericytoma as a distinct clinicopathological entity. However, intracranial haemangiopericytomas are generally aggressive tumours that recur after surgical resection, and if the clinical course of intracranial myopericytomas are to resemble those found elsewhere in the body, a more favourable outcome may be expected. Myopericytoma should therefore be considered in the differential diagnoses of durally-based tumours, particularly those resembling angioleiomyomas and haemangiopericytomas. Further case reports of this rare tumour will play an important role in establishing its clinical behaviour and hence guide patient care.
Declaration of interest: The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.
References 1. Granter SR, Badizadegan K , Fletcher CD. Myofibromatosis in adults, glomangiopericytoma, and myopericytoma: a spectrum of tumors showing perivascular myoid differentiation. Am J Surg Pathol 1998;22:513–25. 2. Rousseau A , Kujas M, van Effenterre R, et al. Primary intracranial myopericytoma: report of three cases and review of the literature. Neuropathol Appl Neurobiol 2005;31:641–8. 3. Lau PP, Wong OK, Lui PC, et al. Myopericytoma in patients with AIDS: a new class of Epstein-Barr virus-associated tumor. Am J Surg Pathol 2009;33:1666–72.
SHORT REPORT
Myopericytoma of the posterior cranial fossa Catherine H. Zhang1, Harutomo Hasegawa1, Paul Johns2 & Andrew J. Martin1 1Department of Neurosurgery, Atkinson Morley Wing, St. George’s Hospital, London, UK, and 2Department of Cellular
Br J Neurosurg Downloaded from informahealthcare.com by Nyu Medical Center on 06/08/15 For personal use only.
Pathology, St. George’s Hospital, London, UK
focal concentric perivascular whorling. Nuclear atypia was modest, mitotic profiles were not identified and no necrosis or brain invasion was found. The Ki67 (proliferative) index was very low. Immunohistochemistry for epithelial membrane antigen (EMA) demonstrated a thin peripheral layer of cells at the lesion margins, in keeping with meningothelial tissue. The stroma and vessel walls were immunopositive for smooth muscle actin (SMA) and h-caldesmon, but negative for desmin (Fig. 2b). Labelling for CD34 demonstrated a layer of unremarkable endothelial lining cells, but was negative in the stromal cells. Despite the unusual location, the overall histological pattern and immunophenotype were felt to be most consistent with a myopericytoma.
Abstract Myopericytoma is a soft tissue tumour believed to be derived from perivascular myoid cells. They are typically found in subcutaneous tissues in the extremities. Intracranial myopericytomas are exceptionally rare. Here we report a man with an asymptomatic posterior fossa myopericytoma with evidence of dural infiltration. Keywords: angioleiomyoma; brain tumour; haemangiopericytoma; myopericytoma
Clinical details A 36-year-old right-handed man of South East Asian origin presented in 2006 with a left-sided Bell’s palsy. Brain MRI revealed an incidental 26 ⫻ 18 ⫻ 15 mm extra-axial, lobular, durally based mass at the right cerebellar convexity, which was hypointense on T1-weighted images, hyperintense on T2-W, and enhanced avidly with contrast. There was no mass effect or hydrocephalus. The patient had no relevant symptoms and the neurological examination was normal other than left facial weakness. The tumour was presumed to be a meningioma and was initially managed with surveillance imaging at his local hospital. It enlarged slowly and the patient was referred for elective excision seven years later, when the tumour had grown to 28 ⫻ 26 ⫻ 20 mm (Fig. 1). A standard midline posterior fossa craniotomy was performed, and a distinct plane was found between the tumour and the brain. The consistency of the tumour was soft in some parts and fibrous in others, vascular, and unusually lobulated. The tumour was attached to the dura on the cerebellar convexity, and this was detached and coagulated. The recovery from surgery was uneventful and a 6-month post-operative MRI confirmed complete resection. Histology showed a highly vascular lesion infiltrating the dura, composed of multiple blood-filled channels of varying sizes (Fig. 2a). The vascular spaces were separated by walls of variable thickness, composed of fibrous tissue and smooth muscle, surrounded by round to oval cells with
Discussion Myopericytoma was described by Granter and colleagues in 1998, as part of their reappraisal of haemangiopericytoma as a clinicopathological entity. It is part of a spectrum of tumours showing perivascular myoid differentiation, which includes myofibromas, glomangiopericytomas and angioleiomyomas. The predominant histological pattern of myopericytomas was described as the presence of round to oval cells with eosinophilic cytoplasm, arranged circumferentially in layers around vascular lumina in an ‘onion-skin’ pattern.1 Macroscopically, they are typically well-circumscribed
Fig. 1. Post-contrast MRI showing a lobulated, enhancing tumour in the posterior fossa.
Correspondence: Dr. Catherine Zhang, Department of Neurosurgery, Atkinson Morley Wing, St. George’s Hospital, Blackshaw Road, London SW17 0QT, UK. E-mail: [email protected] Received for publication 31 May 2014; accepted 3 August 2014
90
Posterior fossa myopericytoma
91
Br J Neurosurg Downloaded from informahealthcare.com by Nyu Medical Center on 06/08/15 For personal use only.
Fig. 2. Low power photomicrographs showing the main histopathological features of the lesion. (a) Routine haematoxylin and eosin (H&E)-stained section showing a well-circumscribed benign vascular tumour composed of small and large anastomosing channels, lined by unremarkable endothelial cells. (b) Immunohistochemistry for smooth muscle actin shows that the walls of the blood-filled spaces contain smooth muscle. Immunolabelling for desmin, EMA and CD34 (not shown) was negative in the stromal cells.
and unencapsulated. Clinically, they are slow-growing and usually painless, mostly found in soft tissues of the extremities, and do not recur after surgical resection. Malignant myopericytomas are rare, but have been reported to occur in the extremities, neck and mediastinum.2 Intracranial myopericytomas are extremely rare. Isolated intracranial myopericytomas have only been described in a case series of three reports by Rousseau et al.2 The cases in this series included a calcified pineal region tumour, a tumour of the orbital apex eroding the sphenoid bone, and an anterior fossa tumour. MRI characteristics were hypointense on T1, hyperintense on T2 and all enhanced with gadolinium contrast. Clinical presentations were with hydrocephalus in the first and with reduced visual acuity in the latter two cases. All three were successfully treated with surgical resection, and no recurrence was reported within 9–12 months for two patients. The other patient (pineal region tumour) died six months after surgery due to an unrelated cause. Only the anterior fossa tumour was reported to show tumour proliferation abutting the dura, but there was no evidence of infiltration. All tumours were immunopositive for SMA and vimentin, and negative for cytokeratins, EMA, CD34 antigen, desmin, and S100 protein. Multifocal myopericytomas involving the intracranial cavity in immuno-compromised patients have been reported in two patients.3 The affected sites were the cerebellopontine angle and the right frontal lobe. The Epstein-Barr virus (EBV) has been suggested as a possible aetiological factor in these cases. Both these patients did not undergo complete resection of the tumours but have survived for many years, leading Lau et al.3 to conclude that multifocal disease may suggest multicentric growth rather than metastasis.
We present the first description of an isolated intracranial myopericytoma arising in the posterior fossa, infiltrating the dura. It is possible that similar tumours were classified as haemangiopericytomas prior to the description of the myopericytoma as a distinct clinicopathological entity. However, intracranial haemangiopericytomas are generally aggressive tumours that recur after surgical resection, and if the clinical course of intracranial myopericytomas are to resemble those found elsewhere in the body, a more favourable outcome may be expected. Myopericytoma should therefore be considered in the differential diagnoses of durally-based tumours, particularly those resembling angioleiomyomas and haemangiopericytomas. Further case reports of this rare tumour will play an important role in establishing its clinical behaviour and hence guide patient care.
Declaration of interest: The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.
References 1. Granter SR, Badizadegan K , Fletcher CD. Myofibromatosis in adults, glomangiopericytoma, and myopericytoma: a spectrum of tumors showing perivascular myoid differentiation. Am J Surg Pathol 1998;22:513–25. 2. Rousseau A , Kujas M, van Effenterre R, et al. Primary intracranial myopericytoma: report of three cases and review of the literature. Neuropathol Appl Neurobiol 2005;31:641–8. 3. Lau PP, Wong OK, Lui PC, et al. Myopericytoma in patients with AIDS: a new class of Epstein-Barr virus-associated tumor. Am J Surg Pathol 2009;33:1666–72.
