A left orbitozygomatic craniotomy was performed for removal of the remaining tumor in the apex of the orbit, and optic canal, followed by local radiation to the tumor bed (5940 cGy). Five years later, the patient presented with tumor recurrence in the floor of the left orbit with bone destruction and extension into the left maxillary sinus. This was successfully treated with resection and radial-free flap reconstruction. The patient has had multiple neuroimaging studies and shows no signs of tumor recurrence 36 months after her last surgery. No evidence of neurofibromatosis type 2 or other meningiomas have been detected in our patient.
A significant feature of meningiomas in childhood is the higher rates of malignant and atypical subtypes in comparison with adults (3,4). In one report, 25% of all meningiomas in the pediatric population showed biological aggressive behavior in terms of disease progression (4). Our patient fit this clinical profile. The main differential diagnoses in a child presenting with an optic nerve tumor are optic nerve glioma and optic nerve meningioma. In our case, complete involvement of optic nerve and restricted diffusion on MRI was also suggestive of a primitive neuroectodermal tumor such as medulloepithelioma (5).
In the pediatric age group, literature regarding the neuroimaging appearance of primary optic nerve meningioma is scant, and no specific pattern has been recognized (1). However, most nerve sheath meningiomas in adult patients have a tubular configuration, followed by other patterns including globular, fusiform, or focal enlargement of the optic nerve sheath (1). Irregular tumor margins in the orbit are indicative of extradural invasion into surrounding tissues (1). MRI is the study of choice for evaluation of optic nerve tumors and should include fat suppression sequences and intravenous contrast (6). Lope et al (7) described the diffusion characteristics of a series of orbital tumors in pediatric patients. In one case, a meningioma demonstrated restricted diffusion; however, they did not generate apparent diffusion coefficient (ADC) values and did not determine the histological type and grade or comment about primary optic nerve meningioma vs extension form an intracranial meningioma.
Multiple studies have found a statistical significance between histopathological subtype of meningiomas and the ADC values, with a tendency for atypical/malignant tumors to have lower ADC values (8,9). Various theories have been proposed to explain the decreased ADC in high-grade tumors including increased tumor cellularity, increased nucleus/cytoplasm ratio, small cell size, fibrous, or gliotic tissues within the tumor or a combination of these factors (10). Ki-67 is an immunohistochemical cell proliferation marker that has been used to differentiate between benign and atypical/malignant meningiomas. In addition, this marker has been shown to be a more reliable predictor of both tumor recurrence and patient survival than histologic grade (11,12). A cutoff Ki-67 index of 10% has been proposed for distinguishing potentially recurrent and nonrecurrent meningiomas (12). In our patient, both restricted diffusion and Ki-67 value were indicative of the malignant nature of the tumor, which recurred despite aggressive initial resection and local radiation.
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