|Year : 2015 | Volume
| Issue : 1 | Page : 51-54
Orbital roof intradiploic meningioma in a 16-year-old girl
Satish Kumar Verma, Gurudutta Satyarthee, Sachin Anil Borkar, Manmohan Singh, Bhawani Shankar Sharma
Department of Neurosurgery, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||2-Apr-2015|
Satish Kumar Verma
Department of Neurosurgery, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Primary intraosseous or ectopic meningioma of the skull is a rare tumor accounting for about 1% of meningioma. Intradiploic meningioma is an extremely rare type of extraneuraxial meningiomas. Intradiploic meningioma of the orbit is extremely rare, and <8 such cases are reported till date in western literature occurring in the pediatric age group. Here the authors present a case of 16-year-old female, who presented with progressive proptosis, with normal vision and was managed successfully surgically. Clinical features, pathophysiology, and surgical management of this rare entity are discussed in the context of pertinent literature.
Keywords: Extradural, intradiploic, meningioma, orbital
|How to cite this article:|
Verma SK, Satyarthee G, Borkar SA, Singh M, Sharma BS. Orbital roof intradiploic meningioma in a 16-year-old girl. J Pediatr Neurosci 2015;10:51-4
| Introduction|| |
Primary intraosseous or ectopic meningioma of the skull is a rare tumor accounting for about 1% of meningiomas. Intradiploic meningioma is an extremely rare type of extraneuraxial meningioma.  It is postulated to arise from arachnoid cell rests captured at inappropriate sites during embryonic development or implantation of these cells by some mechanical insult like trauma or dural tear.  Their origin can also be attributed to cellular dedifferentiation within the diploic space or cranial nerve sheath cells during their course through dipoles. These arise in paranasal sinuses, neck, and orbit and very rarely in diploe of cranial bones. Pediatric orbital roof intradiploic meningioma is reported in the isolated case reports. ,,,, These tumors are observed mostly within the first two decades of life and histologically are usually of psammomatous variety. Here the authors present a case of a 16-year-old female who had progressive proptosis with intact vision and was managed successfully surgically.
| Case Report|| |
This patient presented to our Out-Door Department with complaints of progressive proptosis of the right eye for the last 2 years with associated occasional mild to moderate headache. There was neither associated history of diminution of vision on the affected side nor diplopia in any of the gaze. On examination, there was axial proptosis on right side without any restriction of the extraocular movements. Visual acuity as per Snellen's chart was 6/6 in bilateral eyes with normal visual fields and fundus examination. Rest of the neurological examination was normal. Hematological and biochemical parameters were normal.
Computerized axial tomography (CT) scan with thin cuts of the orbit suggested a hyperdense lesion of about 4 cm × 5 cm size at the orbital roof causing splaying of the outer and inner tables with extension into the superior and supero-lateral aspects of right orbit displacing the globe antero-medially and enlargement of the right orbit [Figure 1]. The lesion extended up to the olfactory groove medially and planum sphenoidale posteriorly. It also encroached upon the ethmoidal, sphenoid and frontal sinuses but without any bony destruction. There was slight hyperostosis of the anterior and lateral part of the orbital roof. The lesion enhanced homogenously intense after contrast administration [Figure 2].
|Figure 1: Preoperative computed tomography (CT) brain axial bone cuts (a). Preoperative CT brain coronal bone cuts (b)|
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Magnetic resonance imaging (MRI) showed T1-weighted iso-hypointense and T2-weighted heterogeneous mass lesion in the right orbital roof with intense postgadolinium enhancement [Figure 3].
|Figure 3: Magnetic resonance imaging (MRI) brain post gadolinium coronal (a). MRI brain post gadolinium sagittal (b)|
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Routine presurgical work-up was done, and the patient was electively taken up for microsurgical excision under general anesthesia. Right fronto-temporal craniotomy with orbitotomy done to expose the tumor. Tumor was found to be completely extra-axial destroying the orbital roof and extending into the basifrontal region and into the sphenoid sinus. Tumor was soft, suckable, pinkish in color and highly vascular. Gross total microsurgical excision including the attached dura mater done. Duraplasty was done using the pericranium graft. Orbital roof was reconstructed using split calvarial bone graft to avoid any postoperative pulsatile proptosis. Bone flap fixed in an esthetic manner and closure done in layers. Lumbar drain was placed to prevent any cerebrospinal fluid (CSF) leak from the basifrontal dura and consequent CSF rhinorrhoea.
Postoperative course was uneventful. Patient is preserved neurologically with excellent cosmetic outcome.
| Discussion|| |
Mostly meningioma are considered as primary intradural lesion, however those originating from location other than meninges are called extra calvarial or ectopic meningioma. They can originate from subcutaneous tissue of skin, paranasal sinus, orbit, neck, salivary gland, calvaria and along per neural sheath of cranial nerves. ,, Winkler in 1904 first described a meningioma originating from extradural location.  Extradural meningioma arising in the skull is usually referred as intraosseous, calvarial or intradiploic. Intraosseous meningioma denotes a subset of extradural meningioma arising in bone and accounts for about two-third of extradural meningioma. Crawford et al. after reviewing 31 cases of intraosseous meningioma, observed that orbital and frontoparietal regions are the most common locations. 
Intradiploic meningioma is very rare in children and reported in isolated case reports. In 2011, Khalatbari et al. could find only seven cases of intradiploic meningioma of the orbital roof published in the western literature and added their one own case in a 14-year-old female.
Crawford et al. reported the diagnostic criteria mass has histopathology consistent with a meningioma, located in epidural and intraosseous compartment; however brain, arachnoid and dura matter is not involved. 
Various hypotheses are postulated to explain its extradural origin. One postulate is that intradiploic meningioma originates from entrapment of arachnoid cells within the bone. Multiple theories exist on how the cells become located in the skull; although none are universally accepted, and different origins are possible. Head trauma, abnormal cranial moldings and embryogenesis, and arachnoid cells accompanying blood vessels and cranial nerves as they traverse the skull, can all result in the entrapment of arachnoid cells or meningocytes in the bone. It is presumed that intradiploic meningioma arise from these entrapped cell rests in the calvarium.
Lang et al. classified primary extradural meningioma in three groups, first being purely extracalvarial, next purely calvarial, and finally the third group represents calvarial meningioma with extracalvarial extension. 
Clinically these case present with exophthalmos, on the involved side, tends to occur predominantly in early second decade of life. However, vision is usually unaffected and in addition they can have a subcutaneous mass.
Radiographically, X-ray can delineate location and its chronic pressure effect on surrounding bone. ,,,,,,, It shows generally osteoplastic or hyperostosis reaction in the form of granular or speckled calcification which involves roof or wall of the orbit. Radiologically intradiploic meningiomas are typically either osteoplastic or osteolytic, however, mixed versions also have been reported although the majority are osteoblastic, extremely rarely are osteolytic or very extremely have a mixed pattern. These can present with opacity of the orbital roof on X-ray skull study. Osteoblastic variety causes hyperostosis, which may mimic fibrous dysplasia. Most of these tumors are benign but malignant transformation is also described. The osteolytic subtype of intradiploic meningiomas are more likely to be malignant than the osteoblastic subtype. Intradiploic meningiomas should be considered in the differential diagnosis of patients presenting with osteoblastic or osteolytic skull lesions. The osteolytic lesions typically cause thinning, expansion, and interruption of the inner or outer tables of the skull and these lesions also enhance homogeneously after contrast administration. However, CT imaging can reveal osteoplastic, intradiploic placement of meningioma, MRI can show better delineation of extension of meningioma and soft tissue involvement.
The osteoblastic variety causes hyperostosis, which may mimic fibrous dysplasia and solitary osteoma. However, clinically intradiploic orbital roof meningioma presents with proptosis, but intraorbital meningioma presents with proptosis and decline in visual acuity to almost complete vision loss. However, CT scan and MRI will clearly delineate even intraorbital meningioma. Rarely rapidly progressing chondrosarcoma, can sometimes occur in orbital wall, is known for aggressive behavior with a high recurrence rate and causes distant metastasis. Hence, preferably orbital chondrosarcoma should be excised along with an eye ball and the orbital contents to prevent recurrence in future.
In the present case, the lesion appeared as an osteolytic variety, with an interruption of the outer table as well as an intact inner table with extensions as described earlier.
Surgery is usually the standard mode of treatment, and all reported pediatric cases had surgical excision, and no recurrence is reported in pediatric cases. However, meticulous reconstruction of the orbital roof is essential and can be done using calvarial bone graft or titanium plate.  In the present case, we achieved complete microsurgical excision of the lesion with reconstruction with split calvarial bone graft with excellent neurological and cosmetic results without any postoperative complications.
Histopathology of previously reported five cases were the psammomatous meningioma with one cases each of transitional, transitional with psammomatous body, and meningothelial meningioma. ,
Khalatbari et al. also reported a case occurred in 14 years who presented with exophthalmos and double vision. CT scan and MRI showed an intradiploic orbital roof tumor causing expansion of diploic space and associated pneumosinus dilatans. She also underwent complete surgical resection, and histopathological study of the specimen revealed the transitional meningioma. 
Authors have previously reported a transitional meningioma in a 40-year-old male, who underwent surgical excision with reconstruction of the orbital roof; he had no recurrence or exophthalmos in the follow-up period. 
| Conclusion|| |
Intradiploic meningiomas are extremely rare lesions and usually do not cause dural infiltration, so extradural complete surgical excision is preferred, and intradural exploration is usually not required. However, intradural exploration is advised only if there is extensive dural infiltration or dural breach is observed. Excellent results can be obtained with proper surgical planning and meticulous surgical technique.
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[Figure 1], [Figure 2], [Figure 3]