The “dural tail” sign: intracranial tumors radiologically mimicking meningiomas

Introduction. The determination of the extra-axial origin of a tumor has a significant clinical importance. The location of the lesion affects treatment planning and it is predictive for prognosis. Classic neuroradiological criteria of extra-axial tumors are a CSF or pial vessels rim which separates the neoplasm from the brain, the intense enhancement after gadolinium administration and the thickening of the dura adjacent the tumor (“dural tail” sign). The “dural tail sign” term was originally coined to define the enhancement of dura mater due to neoplastic infiltration or meningeal hypervascularity and dilated vessels, frequently observed in meningiomas. Meningiomas account for approximately 20-30% of all intracranial tumors and are frequently benign. Thus, in the common opinion, the “dural tail” sign wrongly has become synonymous of meningiomas. However, many other neoplasms either of meningeal or parenchymal origin, benign and malignant, can be associated to a “dural tail” sign on contrast-enhanced Magnetic Resonance Imaging (MRI), thus appearing as meningiomas mimickers. Objects. The aim of our study was to investigate the neuroradiological characteristics of lesions presenting the dural tail sign, in order to facilite the differential diagnosis between meningiomas and other neoplasms. Materials and Methods. At the Neurosurgical Department of the University Hospital of Messina, we retrospectively selected from our database 10 patients who underwent surgery with a neuroradiological diagnosis of intracranial meningioma. All patients underwent morphological Magnetic Resonance Imaging (MRI) examination; some of them underwent Magnetic Resonance Spectroscopy (H-MRS) and Perfusion Computed Tomography (PCT). The neuroradiological data were compared with histological and immunohistochemical markers. Results and Conclusions. In our patients, the neuroradiological diagnosis of meningiomas based on “dural tail” sign was not confirmed by histology, but a wide spectrum of dural, leptomeningeal and parenchymal histotypes were diagnosed. Particularly, at histology, 2 hemangiopericitomas (HPC), 1 metastatic carcinoma, 1 intradural chordoma, 1 leptomeningeal medulloblastoma, 2 hemangioblastomas, 3 high-grade gliomas were documented. H-MRS and PCT provided interesting complementary data, able to increase the specificity of the neuroradiological diagnosis. In conclusion, many intracranial lesions may radiologically mimic meningiomas, showing the “dural tail” sign which is characteristic, but not pathognomonic of this benign tumor. The accurate integration of the neuroradiological, histological and immunohistochemical findings can lead to a correct diagnosis which affects treatment and prognosis.