Presentation
Right eye proptosis.
Patient Data
The right ethmoid sinus is expanded by virtue of a well-defined mass lesion. It measures 4.1 x 4.0 x 4.0 cm along its max axial and CC dimensions. It elicits an intermediate signal on T1 and a predominately low signal on T2 with internal cystic areas. The lesion expands the right ethmoid sinus and extends inferiorly within the roof of the right nasal cavity. It expands the sinus laterally, encroaching upon the right orbital cavity with subsequent proptosis. It bulges intracranially displacing the right frontal lobe superiorly.
Radiological features are suggestive of the right ethmoid sinus ossifying fibroma.
The lesion appears predominantly hyperdense, with internal cystic hypodense areas.
Radiological features are suggestive of the right ethmoid sinus ossifying fibroma.
Pathology after excision showed:
Gross:
Multiple irregular grayish-tan tissue pieces were totally submitted.
Microscopic:
Sections examined from the specimen received revealed pieces of moderately cellular tumor tissue formed of meningeal cells with plump nuclei and minimal pleomorphism, pale eosinophilic cytoplasm, and indistinct cell borders arranged in whorls and lobules with spindling at the periphery of the lobules. There are foci showing spindled cells with elongated nuclei arranged in fascicles. There are many psammoma bodies. There is infiltrating bony tissue. There is a portion of the respiratory epithelium with mucoserous glands. No sheeting or necrosis. No mitotic activity. No evidence of malignancy in the examined sections.
Diagnosis:
Right ethmoid sinus mixed transitional and psammomatous meningioma, WHO grade 1, infiltrating bone tissue.
Case Discussion
Primary extracranial meningioma of the nasal cavity or paranasal sinuses is rare, especially in children. The sinuses most commonly affected are the frontal, maxillary, ethmoid, and sphenoid sinuses.
Theories that have been proposed to explain the primary origin of extracranial meningiomas include:
the presence of arachnoid cells in nerve sheaths or in vessels where they emerge from the central nervous system
migration of meningeal tissue from the meninges to extracranial regions during embryogenesis
traumatic events or intracranial hypertension that displaces arachnoid cells
undifferentiated mesenchymal cells
Differential diagnoses include mucocele, ossifying angiofibroma, hemangioma, lymphoma, and olfactory neuroblastoma.
Extracranial meningiomas are usually misdiagnosed. However, CT and MRI are usually useful in the detection of the extent and invasion of the tumor.
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