A 62-year-old woman experienced symptoms of intermittent
forgetfulness and aphasia that had worsened over a 2-week period.
Her medical history was significant for smoking 2 packs of
cigarettes per day for many years and for a right hemicolectomy as
a result of long-standing Crohn's disease. A noncontrast computed
tomography (CT) of the brain was performed (Figure 1).
Noncontrast CT of the brain revealed what appeared to be an
intra-axial mass of predominantly low attenuation, in the left
frontal lobe (Figure 1). Layering debris levels were present.
Vasogenic edema was evident, as was mass effect with compression of
the left lateral ventricle and small subfalcine herniation. The
overlying calvarium was normal, with no evidence of hyperostosis or
Based upon these findings, magnetic resonance (MR) imaging was
performed and revealed a multilobular, multiseptate cystic mass
with an enhancing mural nodule and enhancement of the cyst wall. A
minimal dural tail was seen (Figure 2). Layering debris was
confirmed. Vasogenic edema and mass effect were again present.
(Figure 3). Several large flow voids were seen at the periphery of
the mass. Chief diagnostic considerations were a primary central
nervous system neoplasm such as astrocytoma, hemangioblastoma, or
ganglioglioma, rather than metastatic disease.
CT of the chest, abdomen, and pelvis and a bone scan were all
negative (not shown).
The diagnosis of typical benign meningioma (nodule and cyst
wall) was established at surgery. The cyst contained xanthochromic
This case provides an opportunity to review both the common and
unusual imaging features of meningiomas. The typical meningioma
will be obviously extra-axial, buckling brain cortex. It is
unilobular, dense on noncontrast CT, and nearly isointense to the
brain on T1- and T2-weighted MR images. Contrast enhancement is
Some findings, such as vasogenic edema and dural attachment, are
common but nonspecific.2 The etiology of vasogenic edema
associated with meningioma is uncertain and debated. Gross
hemorrhage is uncommon.3 Meningiomas are usually
described as solid tumors. Large or multilobular cysts are
uncommon, as is ring enhancement. Cyst formation may be the result
of hemorrhage or necrosis, fluid secretion from the meningioma, or
loculation of cerebrospinal fluid (CSF). Intratumoral and
peritumoral cysts have been described. The intratumoral cysts are
presumably formed from hemorrhage, necrosis, or fluid secretion
within the tumor. Peritumoral cysts are thought by some to be
formed by CSF entrapment as in an arachnoid cyst. Ring enhancement
suggests an intratumoral cyst.1 The atypical features
can easily lead to confusion with glial neoplasms, metastases, or
Meningiomas are common intracranial neoplasms. Atypical features
have been described and radiologic diagnosis requires familiarity
with these features. When confronted with any lesion, one should
consider the uncommon presentation of a common lesion, including
the possibility that several atypical features are present within
the same lesion. When this occurs, even an experienced imager could
- Buetow MP, Buetow PC, Smirniotopoulos JG. Typical, atypical and
misleading features in meningioma. RadioGraphics. 1991;11:
- Wasenko JJ, Hochhauser L, Stopa EG, Winfield JA. Cystic
meningiomas: MR characteristics and surgical correlations. AJNR Am
- Osborn AG, Tong KA. Handbook of Neuroradiology:Brain and Skull.
2nd ed. St. Louis, MO: Mosby; 1996:289-301.