Year : 2010 | Volume
: 53 | Issue : 2 | Page : 319--321
En plaque meningioma with angioinvasion
Keya Basu1, Kaushik Majumdar1, Uttara Chatterjee2, Manojit Ganguli3, Sandip Chatterjee4,
1 Department of Pathology, Nilratan Sirkar Medical College, Kolkata, India
2 Department of Pathology, Institute of Post Graduate Medical Education and Research, Kolkata, India
3 Consultant Pathologist, Park Clinic, Kolkata, India
4 Neurosurgeon, Park Clinic, Kolkata, India
2/91 C Gandhi Colony, PO - Regent Estate, Tollygunje, Kolkata-700 092
En plaque meningioma is a rare type of meningioma characterized by infiltrative nature, sheet-like growth and at times invading the bone. We report here a case of en plaque meningioma with typical grade I histomorphology along with unusual feature of angioinvasion. The patient was a 55-year-old man presenting with headache and painful proptosis of right eye. Imaging modalities revealed an en -plaque meningioma extending into the right sylvian fissure, with thickening of right temporal calvarium, greater wing of sphenoid and extension into the orbit. Magnetic resonance angiography showed medial displacement of right middle cerebral artery. The tumor was removed from the sylvian fissure and right temporal convexity. However, only subtotal removal of the intraorbital part was possible. Histology showed a meningothelial meningioma with low tumor cell proliferation, but infiltration into the bone, skeletal muscle and angioinvasion. Recognition of meningiomas en plaque is useful, as these tumors are difficult to resect completely, and are more prone to undergo recurrence or malignant change. In addition, angioinvasion seen in this tumor may have additional prognostic significance.
|How to cite this article:|
Basu K, Majumdar K, Chatterjee U, Ganguli M, Chatterjee S. En plaque meningioma with angioinvasion.Indian J Pathol Microbiol 2010;53:319-321
|How to cite this URL:|
Basu K, Majumdar K, Chatterjee U, Ganguli M, Chatterjee S. En plaque meningioma with angioinvasion. Indian J Pathol Microbiol [serial online] 2010 [cited 2020 Jul 11 ];53:319-321
Available from: http://www.ijpmonline.org/text.asp?2010/53/2/319/64306
Meningiomas are generally slow growing benign tumors attached to the dura mater and are composed of neoplastic meningothelial cells. They form 24-30% of primary intracranial tumors in the western world.  Most meningiomas are benign; however, certain histological types, including the atypical and anaplastic ones are associated with less favorable clinical outcome. Meningioma en plaque represents a morphological subgroup within the meningiomas defined by a carpet or sheet-like lesion that infiltrates the dura and sometimes invades the bone.  Histopathological features of meningioma enplaque are similar to that of usual meningiomas; however, it is sometimes difficult to predict the behavior in individual cases. Extra-cranial meningiomas form 1-2% percentages of all meningiomas.  The en plaque variants commonly involve fronto-parietal, juxtaorbital, sphenoid wing, diffuse calvarial or rarely spinal region. ,,, Due to difficulty in complete resection, the recurrence rate of en plaque meningiomas is higher than the usual counterpart. , These tumors are also more prone to develop malignant change (11%) when compared to intracranial meningiomas (2%). ,
A 55-years-old man presented with headache and painful axial proptosis of the right eye. Computed tomography (CT) scan showed evidence of thickening of roof of the lateral wall of right orbit with evidence of proptosis. There was also thickening of right greater wing of the sphenoid and right temporal calvarium. Magnetic resonance (MR) Imaging of brain showed an en plaque meningioma extending into the right sylvian fissure with extension into right temporal and parietal convexity and extension into the orbit [Figure 1]a and [Figure 2]b. MR angiography revealed medial displacement of the right middle cerebral artery.
A right fronto-temporo-parietal free flap was raised and the tumor was removed completely from the Sylvian fissure and right temporal convexity. However, only subtotal removal of intraorbital part was achieved after drilling the roof and lateral wall of the right orbit, due to the proximity of the tumor to right middle cerebral artery. The bone flap raised was removed as it was found to be completely infiltrated with tumor. Post-operative MR scan showed satisfactory tumor removal without any recurrence after 14 months of surgery.
Microscopic examination of tumor showed the features of meningothelial meningioma with cells arranged in sheets and whorls, having indistinct cell borders and vesicular nuclei. On hematoxylin and eosin (H and E) stain, there was no increase in the mitotic activity or evidence of necrosis. However, tumor infiltration into the bone and overlying soft tissues including skeletal muscles [Figure 2] a and b was seen. Interestingly, extensive angioinvasion [Figure 2]c and d of the dural vascular channels was also noted. Immunohistochemical staining for PCNA showed a low labeling index.
The term "en plaque" had been described by Cushing as '"flat spreading carpets of tumor'". , Meningioma en plaque is a specific clinicopathological entity, which although locally invasive, usually bears the histology of WHO grade I meningioma. Tumor with diffuse and extensive dural involvement and extracranial extension into calvarium, orbit, soft tissues including skeletal muscle and angioinvasion, as seen in this case has been rarely described. Occurring commonly in the sphenoidal ridge, calvarium or spinal region, these tumors have a "collar like" or "sheet like" growth along the dura, unlike the usual globular meningiomas. 
Calvarial thickening at the site of origin of meningiomas is common and the meningothelial cells are well known to invade and expand the bone.  Hyperostosis, seen frequently in en plaque variants is associated with infiltration of the medullary spaces by whorls and syncyitia of meningothelial cells. ,, The present case also showed similar bony invasion. Meningiomas presenting with scalp swelling, osteolytic lesions and extracranial soft tissue masses may be more aggressive in nature.  CT and MR imaging are useful to evaluate the extent of extradural and calvarial involvement;  early recognition can help to determine the extent of surgery and provide a better prognosis.
Meningiomas have traditionally been divided into benign, atypical and anaplastic categories.  This case showed features of a benign meningioma with no evidence of necrosis or increased mitotic activity. Evidence of bone infiltration through osseous canaliculi is not considered as the evidence of malignancy. However, the significance of angioinvasion as seen in our case has not been reported and is not known.
Successful treatment of these tumors is a challenging proposition. Complete resection in most cases is almost impossible due to extensive dural and calvarial involvement, and proximity to vital structures. ,, Partial removal, though causes relief of symptoms, can lead to higher chance of recurrence.  In the case described here, intraorbital part of the tumor could not be completely removed because of the close proximity of the middle cerebral artery; though the patient continues to be free of tumor for a follow up of 14 months, further long-term follow-up is warranted.
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