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TOPICS COVERED IN THIS SITE Introduction
Surgical treatment in meningiomas.
Histological aspects in meningiomas.
Supratentorial meningiomas in general.
Parasagittal meningiomas.
Falx meningiomas.
Convexital meningiomas
Olfactory groove meningiomas.
Tuberculum sellae meningiomas.
Sphenoid wing meningiomas.
Optic sheath meningiomas.
Middle fossa meningiomas.
Cavernous sinus meningiomas.
Intraventricular meningiomas.
Malignant meningiomas.
Peritorcular meningiomas.
Tentorial meningiomas.
Infratentorial meningiomas.

Meningiomas outside the nervous system.


Skyra 3 tesla magnetom running in the neurosuite since
28-November-2013

 

  Extracranial meningiomas of the head and neck region are rare neoplasms, the majority being a secondary location of a primary intracranial tumour. Prognosis of this tumour is generally excellent.
Surgical excision is the treatment of choice, with no need for further treatment; nevertheless, differential diagnosis must consider other more common tumours of the head and neck and be based on histopathologic examination and relative techniques, including examination of frozen sections. This procedure is particularly useful assessing surgical treatment and should be performed whenever possible to exclude the malignant nature of the lesion and avoid over-treatment.

Introduction

According to the World Health Organization, meningioma is a tumour arising from arachnoidal cells and, in the majority of cases, its behaviour is benign. It accounts for 24-30% of all intracranial tumours and has an incidence of 13/100,000 per year.
Extracranial meningiomas are rare; the majority have a secondary location of a primary intracranial tumour. Therefore, once the diagnosis of meningioma is established, the presence of a meningioma of the neuraxis or extension of a primary central meningioma must be excluded.

Case demonstration:


The patient came to the clinic 29-April-2014 complaining of difficult breathing fro the right nostril with progressive exophthalmus right eye for one year. He was operated for septal deviation elsewhere without benefit. CT-scan done 29-April-2014 showing a huge mass in the right maxillo- sphenoidal area, pushing the septum to the left and elevating the medial wall of the right orbit up and lateral.
On examination; the patient has no visual problems except the right exophthalmus. The lacrimal duct is closed and the tears are running outside the canal. It was possible to see the tumor through the right nostril. It was totally obstructing the passage.
The patient was sent for MRI investigations with contrast with MRA of the brain and carotid systems. There was no arterial involvement and the mass was totally extracranial, but reaching and abutting the pituitary floor and shifting the right optic nerve medially.
Through the right nostril, the tumor was attacked and piece-meal resection was performed. Fresh frozen biopsy telling that it is either meningioma or fibrous dysplasia. Inspection of the tumor bed cavity was negative. Intraoperative MRI done showing huge remnant of the tumor, which was followed and resected. Hemostasis. 2 nasal tubes were inserted.
Smooth postoperative recovery.
The patient is not characteristic for either meningioma, nor for fibrous dysplasia. It is benign and grossly looking as chordoma.
Intraoperative MRI is superior to the usual inspection, as in this case.


Figure-1


Figure-2

In retrospective analysis of the MR Spectroscopy done before surgery, it was similar to pattern seen intracranially as seen in Figure 1 and 2.

Discussion

Primary extracranial meningiomas of head and neck region are rare tumours, the majority being a secondary location of a primary intracranial tumour, accounting for 1-2% of all meningiomas and with a generally favorable prognosis.

Therefore, once the diagnosis of meningioma is established, the presence of a meningioma of the neuraxis or extension of a primary central meningioma should be excluded. The most frequent extracranial sites reported are the nasal cavity and paranasal sinuses, cranial bones, middle ear, scalp and soft tissues of the face and neck and parotid gland. The largest series of extracranial head and neck meningiomas encompass 146 cases, among which the majority was of the skin and scalp (n = 59), middle ear (n = 26), nasal cavity (n = 17), temporal bone (n = 2) and parotid gland (n = 1). Other large series consider the sinonasal tract (n = 30) 6, ear and temporal bone meningiomas.
The etiology of extracranial meningiomas resides in the migration of arachnoid cells deriving from the neural crest, but different mechanisms have been proposed such as originating from arachnoid cells of nerve sheaths emerging from skull foramina, from Pacchionian bodies possibly displaced or entrapped in an extracranial location during embryologic development, by trauma or cerebral hypertension displacing arachnoid islets or deriving from undifferentiated mesenchymal cells.
Extracranial meningiomas exhibit various different histologic patterns just as their intracranial counterparts.
By cytology, meningotheliomatous cells show bland nuclei with delicate chromatin and intranuclear pseudoinclusions. The immunohistochemical profile of extracranial meningiomas is indistinguishable from intracranial lesions. All tumours expressed epithelial membrane antigen and vimentin, variable expression of protein S-100 and are negative for acidic gliofibrillary protein.
Although the lesions has a radiographic and histological growth pattern that is aggressive, none were diagnosed as a malignant meningioma. Their indolent clinical behaviour was further suggested by cellular immunoreactivity for Ki-67, which was less than 5%. Differential diagnosis includes different benign and malignant tumours, such as epithelial neoplasms (carcinoma), tumours originating from the neural crest (melanoma, olfactory neuroblastoma) and vascular and mesenchymal tumours (angiofibroma, paraganglioma, ossifying fibroma).
Histologic features and immunohistochemical findings can easily separate these entities, especially in the differential diagnosis between carcinoma and melanoma; in more intriguing cases immunohistochemistry for cytokeratins, S-100 protein and HM B-45 allows distinction from meningiomas.
Prognosis of primary meningioma is generally excellent, thus supporting the indolent growth of meningiomas, except for rare malignant forms; surgical excision is the treatment of choice, with no need for further treatment. Recurrences usually develop in the same site as the primary lesion and probably represent residual disease rather than recurrent tumour.
Clinical and radiographic features of these tumours cannot predict the nature of these lesions. Therefore, histopathologic examination is necessary as it can distinguish these
neoplasms from other head and neck tumours. In particular, frozen sections are particularly useful in assessing the surgical procedure and should be performed whenever possible to exclude the malignant nature of the lesion and avoid overtreatment.

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