Neuroimage

Cyst with a mural nodule: Unusual case of brain metastasis

A. Garg, A. Suri,* V. Gupta Department of Neuroradiology and *Neurosurgery, AIIMS, New Delhi, India.

A 34-year-old woman presented with history of headaches, vomit- ing and progressive left hemiparesis for the last 3 months. CECT showed right frontal juxtaventricular, cystic lesion with an enhanc- ing mural nodule and focal wall (Figure 1a). On MRI, the cyst was hypointense on T1WI (Figure 1b) and hyperintense onT2WI (Fig- ure 1c) and suppressed on FLAIR sequence (Figure 1d). Per-opera- tively, a cyst with yellowish clear fluid and a small grayish, solid part were removed. The cyst walls were not necrotic. HPE revealed a malignant tumor composed of cells with focal areas of glandular dif- ferentiation with marked pleomorphism. The tumor cells were im- munoreactive for cytokeratin and mucin. The wall of the cyst showed gliosis. A diagnosis of metastatic adenocarcinoma was made. No pri- mary could be localized. The radiological differential considerations for a cystic tumor 1a 1b with an enhancing mural nodule include pilocytic astrocytoma, hemangioblastoma, pleomorphic xanthoastryocytoma, menin- gioma and ganglioglioma.1,2 The radiological finding of a cystic tumor with a mural nodule had not been described previously in brain metastases. The presence of minimal edema relative to the size of the lesion in our case was also unusual for a metastatic deposit. FLAIR sequences have been reported to be useful in distinguishing between cystic neoplastic and non- neoplastic lesions.3 The cyst had suppression of signal inten- sity on FLAIR imaging, thereby suggesting non-mitotic pa- thology. This unusual appearance is possibly attributed to the 1c 1d lack of proteinaceous or myxoid material inside the cyst, which is rare in metastasis. Therefore, FLAIR images should be Figures 1a - 1d: Contrast enhanced CT (Figure 1a) shows a cytic lesion with an enhanced mural nodule (white arrow) in right frontal lobe. Cyst interpreted with caution. has smooth, thin wall with focal wall enhancement and minimal edema. Cyst follows CSF signal intensity on TIWI (Figure 1b) and slightly hyperintense to CSF on T2WI (Figure 1c) and suppression of signal on References FLAIR image (Figure 1d). Mural nodule is isointense to gray matter on T 1 WI (black arrow) (Figure 1b) and T2WI (Figure 1c) 1. Maiuri F. Cysts with mural nodules in the cerebral hemispheres. Neurosurgery 1988;22:703-6. 2. Tomita T, McLone DG, Naidich TP. Mural tumors with cysts in the cerebral Recovery MR imaging. AJNR Am J Neuroradiol 1999;20:1259-67. hemisphere in children. Neurosurgery 1986;19:998-1005. 3. Aprile I, Iaiza F, Lavaroni A, Budai R, Dolso P, Scott CA, et al. Analysis of cystic intracranial lesions performed with Fluid-Attenuated Inversion Accepted 10.09.2003.

Vipul Gupta Department of Neuroradiology, Neurosciences Center, All India Institute of Medical Sciences, New Delhi - 110029, India. E-mail: [email protected]

136 Neurology India March 2004 Vol 52 Issue 1 136 CMYK