SPHENOID MENINGIOMA OCCURRING AS A LATERAL ORBITAL MASS
ABSTRACT
The differential diagnosis of a mass presenting in the lateral aspect of the orbit with bony erosion and involving the skin includes many malignancies, predominately sarcomas. A total evaluation of the mass to include histopathologic characteristics and the true extent if the disease is critical to proper management of the patient.
A 68 year-old man was referred for therapy with a diagnosis of fibrosarcoma. Evaluation of the disease revealed contiguous tumor from the right temporal region into the posterior orbit, with displacement of the globe and extension intracranially. During operation a frozen section analysis of the tumor was also interpreted as fibrosarcoma. A craniofacial resection was performed, including orbital exenteration and resection of a large 10X12 cm segment of attached dura. There was no evidence of extension into the brain. Final pathologic evaluation of the tumor was meningioma rather than fibrosarcoma. This unusual presentation of a meningioma has never been reported in the medical literature. The difficulty with interpretation of the original biopsies will be discussed, as well as the management of this case.
The differential diagnosis of a mass presenting in the lateral aspect of the orbit with bony erosion and involving the skin includes many malignancies, predominately sarcomas. A total evaluation of the mass to include histopathologic characteristics and the true extent of the disease is critical to proper management of the patient. A case is reported of a spheniod wing meningioma which presented as a mass lateral to the right orbit. A frozen section analysis of the tumor was interpreted as fibrosarcoma, which was consistent with the previous diagnosis from another pathologist. Final evaluation of the tumor following resection was meningioma rather than fibrosarcoma. This unusual presentation has never been reported in the medical literature. The difficulty with interpretation of the original biopsies, as well as the management of the case, will be discussed.
CASE REPORT
A 68 year-old man, W.O. was referred for therapy with a diagnosis of fibrosarcoma. For 2 months, he had noted an asymptotic swelling over the right temple. An open biopsy done during exploration of the mass was interpreted as a low grade fibrosarcoma.
The patient was referred to the University of Arkansas Head and Neck Oncology Service for further evaluation and treatment. Evaluation of the swelling revealed a firm, non-tender, soft tissue mass overlying the right frontal bone. This mass ballotted with another beneath the right zygomatic arch, but did not clinically involve the orbit. Consultation with an ophthalmologist confirmed that there was no clinical orbital involvement. A computerized tomographic scan revealed contiguous tumor from the right temporal region of the face and scalp into the posterior orbit with displacement of the lateral rectus muscle in a medial direction. The lateral orbital wall was eroded by tumor. The mass measured 3x3x6 cm and invaded into the right middle cranial fossa, abutting the dura. This intracranial extension, however, did not appear to involve the brain.
At surgery, a frozen section analysis of the tumor was performed both in the soft tissue lateral to the orbit and in the tissue within the orbit. This frozen section was interpreted as fibrosarcoma, which was consistent with the pervious diagnosis. A craniofacial resection was performed, including orbital exenteration and resection of a large, 10x12cm segment of attached dura. Extracranially, the tumor extended from the lateral orbital tissue to below the zygomatic arch and into the infratemporal fossa. Intracranially, there was no evidence of brain involvement and tumor-free margins were successfully obtained on the dura. Postoperatively the patient healed without difficulty and has remained free of disease for over 15 months. Rehabilitation with a facial prosthesis has been successfully accomplished.
PATHOLOGIC EXAMINATION
Examination of the surgical specimen revealed a tumor which originated along the spheniod wing, invaded through the bone of the lateral orbital wall, and presented itself as a subcutaneous mass lateral to the orbit. Light microscopy showed a highly cellular, pleomorphic, spindle-cell tumor consistent with either fibrosarcoma or meningioma. Multiple mitoses were in evidence, as well as granulofilamentous inclusion bodies in the cytoplasm. The latter have recently been described in meningiomas. Electron microscopy revealed abundant, thick microfilaments within the cell bodies. There were numerous cytoplasmic interdigitating processes between the cells that were attached by desmosomes.
DISCUSSION
Meningiomas comprise 15% of all intracranial tumors. Usually of good prognosis, they are commonly well-circumscribed, seldom metastasize, and are slow to invade surrounding tissue in a infiltrative fashion. They spread by direct extension along the plane of least resistance and extend into bone along the haversian canals, rather than by erosion. Sporadically, a highly malignant, atypical variant of meningioma has been reported that is aggressive to invade tissue and metastasize early.
These tumors are thought to be hamartomatous, arising from the arachnoid villi. The most widely accepted classification is based on the predominant cell type and pattern of histology within the tumor. Five sub-groups of classification are recognized:
- Meningotheliomatous (syncytial)
- Fibroblastic
- Mixed or transitional
- Angioblastic
- Sarcomatous
Diagnostic differentiation is often difficult between these sub-groups and also among other neoplasms of soft tissue because of the numerous histopathological features which are common to them. In this case, microscopic evidence of a cellular spindle-cell tumor was interpreted as fibrosarcoma. This diagnosis verified the clinical finding of a lateral orbital mass, as well.
This unusual presentation of a meningioma was confirmed only when the tissue was examined under the electron only when the tissue was examined under the electron microscope. Presence of desmosomes and cytoplasmic interdigitating processes and inclusion bodies confirmed the diagnosis.
This particular clinical presentation of a meningioma has never been reported in the medical literature. This diagnosis must be considered in the interpretation of masses of the soft tissue lateral to the orbit.