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.
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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.
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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.
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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.
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