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The extracranial component of an intracranial meningioma is common and may present clinically as an isolated mass in the head and neck region. Conversely, primary extracranial meningiomas with intracranial extension are rarer and we report one such case diagnosed at fine needle aspiration in a 41-year-old woman presenting with a solitary cheek swelling of two years duration. The cytological diagnosis prompted imaging studies which highlighted the intra-cranial component. Subsequent histopathology and IHC study seconded the cytological diagnosis. Thus, diagnosis at FNAC at rare sites is quite challenging and may get missed if the eyes don't see what the mind doesn't know!
The index case is that of a 41-year-old lady who presented with a left cheek swelling of two years duration associated with on and off left-sided headache. The swelling had a gradual onset and slowly increasing in size. It was an ill-defined soft, non-tender 4×3 cm swelling causing fullness of the left cheek [Figure 1]a. No regional lymph nodes were palpable. The oral cavity, dentition, and the floor of the mouth were normal. With a clinical diagnosis of? Schwannoma/Lymphoma, a transnasal FNAC was performed as an outpatient procedure. The cellular smears stained with Haematoxylin-Eosin and Papanicolaou stains showed cohesive clusters of plump ovoid spindle cells forming tight whorls at places [Figure 1]b, [Figure 1]c & [Figure 1]d. These cells showed bland nuclear morphology with fine chromatin, abundant eosinophilic cytoplasm, indistinct cell borders with specs of calcification [Figure 1]d. With the distinct cellular whorls and calcification in the form of psammoma bodies seen with minimal or no spindle cell component, a cytological diagnosis of meningioma was made. Immunocytochemistry done thereafter showed diffuse intense cytoplasmic positivity for CK, EMA, Vimentin [Figure 1]e, [Figure 1]f, [Figure 1]g, S100, and was negative for synaptophysin and chromogranin, excluding nerve sheath tumor and paraganglioma. Imaging studies were recommended to look for an intra-cranial component of meningioma. A CT scan of skull base till neck (with contrast) showed a heterogeneously enhancing lesion measuring 5 × 4.4 × 4 cms in the left retro maxillary space and masticator space with intracranial extra axial extension of the tumor of size 1.5 × 0.81 × 0.84 cm along the meninges in the left parasellar region with widening of left foramen rotundum suggesting left maxillary nerve involvement [Figure 1]h. The lesion was completely excised with a craniofacial approach. The histology was that of meningothelial meningioma (WHO grade 1) [Figure 1]i and was ratified by immunohistochemistry with diffuse cytoplasmic positivity for vimentin, EMA, PR and S100, and negative for GFAP. With the final diagnosis of primary extracranial meningioma with intracranial extension, the patient was advised regular follow-up. The patient, as of date, is asymptomatic with repeat CT scan showing no tumor recurrence.
Figure 1: a: Clinical photograph showing a diffuse swelling over the left cheek. b-d: Note cohesive clusters of polygonal cells with bland nuclei, fine chromatin, abundant eosinophilic cytoplasm and indistinct cell borders [b (H and E x40), c (H and E x200], and specs of calcification in d (H and E x200). e-j: Immunocytochemistry showing intense (3+) diffuse cytoplasmic positivity for CK (e), EMA (f) and Vimentin (g). h: Pre-operative contrast CT axial section scan showing large ill-defined heterogeneous enhancing isodense lesion in left infra temporal fossa with soft tissue mass along temporalis muscle. i: Section shows classical histology of meningioma with a psammoma body (H&E x 200) 
Discussion 
Meningiomas are indolent intra-cranial neoplasms accounting for about 18% of primary intracranial tumors and 25% of primary intra-spinal tumors[1] while extra cranial extension of intracranial meningiomas are seen in only 20% of cases.[2] Isolated presentation of extra-cranial and extra-spinal meningiomas are uncommon with an incidence of 1 to 2%.[3] This case is probably the first of primary extracranial extraspinal meningiomas of the cheek being diagnosed prospectively, with FNA prompting for a look-out for an intracranial component. FNA diagnosis was considered a challenge owing to the unusual site of occurrence, specially being the extra-cranial site.
Isolated solitary cheek swelling in the patient demanded attention and its diagnosis of meningioma prompted further investigation for intracranial extension at the right time before the major surgery was taken up. To date, only 19 cases of isolated meningioma in the oral cavity have been reported to the best of our knowledge; 6 of which presenting with cheek swelling were purely extracranial and their diagnoses were made only on histopathology,[4],[5],[6] making this case unique where the final diagnosis of meningioma was first made on cytology, which prompted imaging studies and further evaluation for the intracranial component.
The fact that the cheek swelling was large and of long duration, hints at being an extra-cranial meningioma initially and progressing with an intracranial component which is very small has shown early extension into foramen rotundum resulting in headache and features suggesting left maxillary nerve involvement. Thus, this index case, to begin with was primarily an extracranial extra axial meningioma showing progression at a later date with an intracranial component.
The cytological and histopathological criteria of extracranial meningiomas are similar to those of their intracranial counterparts. All the reported cases share the same features, namely, whorls of spindle cells of uniform round-to-oval cells in a syncytial and whorled pattern or epithelioid cell proliferation and psammoma bodies with no nuclear atypia. Most of the cases reported in the literature confirmed their diagnosis using immunohistochemistry with the tumor cells staining positive for monoclonal antibodies against EMA, cytokeratin, vimentin with variable response to S100 and negative for synaptophysin and chromogranin, excluding a possibility of paragangliomas, nerve sheath tumor and metastatic carcinomas. Further, timely recommendation to the surgeon to look for an intracranial extension as done in this case, helped him to change the surgical planning to a combined craniofacial approach which guided him for a total removal of the meningioma. This is important to note, as these cases also require prior antibiotic prophylaxis, vaccine for preventing meningitis, neurosurgery support, be guarded to anticipate any surgical complication, and a good follow-up for they have a high recurrence rate. Thus, an eye for cellular whorls associated with specs of calcification at cytology, should prompt one a diagnosis of meningioma in any head and neck swelling. Beware of common lesions at uncommon sites, as the right cytological diagnosis is made available at the right time for further appropriate patient management. One should remember to expect the unexpected when similar lesions are encountered.
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The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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References 
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CheckDOI: 10.4103/joc.joc_84_21
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