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A clinical impression of a frontal space occupying case include the butterfly configuration, forniceal
lesion (SOL) was considered in view of a history thickening and features of a “mass-effect” with a clinical
suggestive of mesial and orbitofrontal dysfunction with presentation akin to a butterfly glioma; prominent
suspicion of white-matter (WM) involvement in view of differentiating features being the enhancement and
pyramidal signs. The initial magnetic resonance imaging perfusion patterns. The differential diagnosis of
(MRI) [Figure 1] revealed an ill-defined butterfly shaped acute-subacute acquired “butterfly lesions” involving
intra axial SOL involving bilateral frontal lobes as well the corpus callosum as seen in the patient represents
as anterior insula with predominant involvement of a challenge in itself with multimodal imaging playing
subcortical deep WM and extension into bilateral caudate a crucial role. A host of etiologies can be broadly
nuclei, genu and the anterior 1/3 of body of corpus grouped as: tumors such as glioma, lymphoma and
callosum. Moderate mass-effect over bilateral frontal metastasis; inflammatory demyelinating pathologies
horns of lateral ventricles was observed. The lesion like tumefactive MS; infections such as progressive
was hyperintense on T2-weighted and hypointense on multifocal leukoencephalopathy and Whipple’s
T1-weighted images with mild diffusion restriction over disease; toxins leading to disseminated necrotizing
the periphery. Peripheral enhancement was noted on leukoencephalopathy, e.g. intrathecal or systemic
intravenous gadolinium administration. There was no exposure to methotrexate or cytosine arabinoside and
MR evidence of calcification or hemorrhage within the acute radiation necrosis. Imaging characteristics that
[1]
lesion. MR spectroscopy (MRS) from the intermediate potentially differentiate these conditions are depicted
part of the lesion revealed elevated choline peak, in Table 1. Clinico-radiological presentation of a
reduced N-acetyl aspartate (NAA) and the presence of non-neoplastic pathology like tumefactive demyelinating
lactate; however perfusion values were noted to be low lesion (TDL) resembling a butterfly glioma is fraught
in the lesion. with chance of a misdiagnosis (due to heterogeneity of
imaging characteristics within the lesion itself).
On admission, the patient was noted to develop rapidly
progressive encephalopathy with features of raised Unlike in our patient, TDL tend to be circumscribed
intracranial pressure in the form of bradycardia, lesions with mild mass-effect or vasogenic
hypersomnolence and hypertension. With the imaging edema. These typically involve the supra-tentorial
[2]
consideration of an intermediate-high grade SOL WM although they may extend to involve the cortical
and gliomatosis cerebri high on the cards in view gray matter with gyral edema. In a large series of
of a butterfly-patterned lesion with calloso-forniceal 168 patients with biopsy confirmed central nervous
thickening [Figure 1a], a neuronavigation-guided biopsy system inflammatory demyelinating disease, frontal
and as an alternative a frontal decompressive procedure and parietal subcortical regions were most often
was considered. The frozen-section specimen and affected and a butterfly configuration involving the
histopathology report [Figure 2] was consistent with [3]
tumefactive demyelination hence decompression corpus callosum was observed in only 12% of cases.
was not performed. Such a presentation mimicking Forniceal thickening was not described in this series
a butterfly glioma is extremely rare. The patient was and represents a unique observation in our patient
treated with pulse methyl predisolone followed by oral as this deviated the impression towards a neoplastic
prednisolone that was administered in a dose of 1 mg/kg etiology. Approximately half of TDL have pathological
for 8 weeks followed by slow taper and cessation contrast enhancement, usually in the form of ring
over 1 year. Prior to discharge evoked potentials, and enhancement. [2,3] A variety of intracranial pathologies
cerebrospinal fluid studies including oligoclonal bands can present as a ring-enhancing lesion (REL) on MRI,
were negative thereby making multiple sclerosis (MS) including glioma, metastasis, lymphoma, radiation
less likely. Dramatic clinical improvement was noted, necrosis, infarct, abscess and tumefactive demyelination.
and the patient returned to the premorbid personality Although less common in typical demyelination, REL
with normal neuropsychological performance 3 months are more likely to be biopsied in order to exclude
into treatment. Serial MRI [Figure 3] verified gradual these other pathologies that are mandatory from a
resolution of the WM hyperintensities and contrast treatment and prognostication point of view. In a recent
enhancement with development of minimal bifrontal series among the most prevalent pathologies associated
atrophy. MRS at 1 year showed reduction in the choline with ring enhancement, demyelinating lesions of
peak with reduced NAA and no evident lactate peak. MS constituted a small number (6%) and patterns of
T2-weighted hypointensity are useful to differentiate
DISCUSSION between pathologies. Figure 1b and c demonstrate this
[4]
pattern of enhancement in the patient. The enhancing
The neuroimaging characteristics distinctive in the portion of the ring is believed to represent the leading
pattern of tumefactive demyelination in the index edge of demyelination and thus favors the WM side of

174 Neuroimmunol Neuroinflammation | Volume 2 | Issue 3 | July 15, 2015 Neuroimmunol Neuroinflammation | Volume 2 | Issue 3 | July 15, 2015 175