Signs in Imaging-The Dural Tail Sign

Eric W.Wallace,MDThe Dural Tail Sign 1APPEARANCEThe dural tail sign is seen on contrast material–enhanced mag-netic resonance (MR)images as a thickening of the enhanced dura mater that resembles a tail extending from a mass (Figs 1,2).EXPLANATIONPrecise pathophysiologic understanding of the dural tail typi-cally associated with meningioma is less than complete.It was initially proposed that dural tails resulted from direct tumor invasion (1),but many later investigators (2,3)were able to show little or no direct tumor involvement.It was therefore proposed that dural tails represented reactive changes to the dura mater,with perhaps minimal changes to meningothelial nodules that were adjacent to but not in contiguity with the tumor.Meningiomas are known to be hypervascular,which results in additional adjacent reactive changes such as hyper-ostosis and sinus blistering (4).It is reasonable that both mech-anisms (tumor invasion and hypervascular reaction)may be responsible for the dural tail sign.DISCUSSIONAn early clinical description of meningioma was reported in 1614(5).Unfortunately,at that time the diagnosis could be made only after death.In 1902,George E.Pfahler,MD,then a resident physician,was able to offer a radiologic diagnosis on a living patient.Pfahler described the “tumor shadow”of a meningioma on conventional radiographs (5).In 1989,Wilmset al (1)described dural tails that were associated with menin-giomas on MR images.Disagreement exists in the literature regarding the impor-tance of dural tails on meningiomas.Some extraaxial tumors (eg,vestibular schwannomas)are difficult to distinguish from meningiomas,and accurate diagnosis could be facilitated with a sensitive and specific sign.In 1990,Goldsher et al (2)pub-lished a report on 30meningiomas,of which 60%had tails.The authors devised radiologic criteria to reliably establish the presence or absence of dural tails.Three criteria were adopted:(a)The tail should be identified on two successive sections through the tumor,(b)the tail should taper smoothly away from the tumor,and (c)the tail must have an enhancementAtrainee (resident or fellow)wishing to submit a manuscript for Signs in Imaging should first write to the Editor for approval of the sign to be prepared,to avoid duplicate preparation of the samesign.Figure 1.Coronal T1-weighted spin-echo MR image (repetition time msec/echo time msec,400/20)of the brain with intravenous gado-linium enhancement shows dural tail (arrow)attached to a typical meningioma (arrowhead).Signs in Imaging56greater than that of the tumor itself.Given this strict de fini-tion,none of the 41nonmeningioma tumors in the control group,including extraaxial or super ficial tumors,met the cri-teria for a dural tail.Goldsher et al thus concluded that dural tails were a “highly speci fic feature of meningiomas ”(2).Although findings from a few studies have supported the fact that the presence of a dural tail is at least suggestive of meningioma (60%–72%of meningiomas have a tail)(2,6),many cases have now been reported of dural tails that are attached to nonmeningioma tumors (or tumefactive pro-cesses).To date,dural tails have been documented adjacent to chloroma,primary central nervous system lymphoma,sarcoid-osis,vestibular schwannoma,metastatic tumor,syphilitic gumma,and an aggressive papillary middle ear tumor (7–10).No clear answer can be discerned from the literature as to why some tumors cause a dural tail and others do not.In the particular case of meningiomas,some investigators have noted tumor invasion,and others relate the tail to hypervascular reaction.These two common explanations (namely,aggressive in filtration and in flammatory reaction)are also noted for most of the nonmeningioma tumors.Whatever the explanation,the dural tail sign remains a helpful sign at least suggestive of meningioma.Acknowledgment:Much gratitude and high regard are extended to Joon Kie Kim,MD,for his expert assistance in this project and others.References1.Wilms G,Lammens M,Marchal G,et al.Thickening of durasurrounding meningiomas:MR features.J Comput Assist Tomogr 1989;13:763–768.2.Goldsher D,Litt AW,Pinto RS,Bannon KR,Kricheff II.Dural “tail ”associated with meningiomas on Gd-DTPA-enhanced MR images:characteristics,differential diagnostic value,and possible implica-tions for treatment.Radiology 1990;176:447–450.3.Tokumaru A,O ’uchi T,Eguchi T,et al.Prominent meningealenhancement adjacent to meningioma on Gd-DTPA-enhanced MR images:histopathologic correlation.Radiology 1990;175:431–433.4.Rowbotham GF.The hyperostosis in relation with the meningi-oma.Br J Surg 1939;26:593–622.5.Siegelman ES,Mishkin MM,Taveras JM.Past,present,and futureof radiology of meningioma.RadioGraphics 1991;11:899–910.6.Aoki S,Sasaki Y,Machida T,Tanioka H.Contrast-enhanced MR images in patients with meningioma:importance of enhance-ment of the dura adjacent to the tumor.AJNR Am J Neuroradiol 1990;11:935–938.7.Bourekas EC,Wildenhain P,Lewin JS,et al.The dural tail sign revisited.AJNR Am J Neuroradiol 1995;16:1514–1516.8.Tien RD,Yang PJ,Chu PK.“Dural tail sign ”:a speci fic MR sign for meningioma?J Comput Assist Tomogr 1991;15:64–66.9.Kutcher TJ,Brown DC,Maurer PK,Ghaed VN.Dural tail adjacent to acoustic neuroma:MR features.J Comput Assist Tomogr 1991;15:669–670.10.Senegor M.Prominent meningeal “tail sign ”in a patient with a metastatic tumor.Neurosurgery 1991;29:294–296.Figure 2.Sagittal T1-weighted spin-echo MR image (415/20)of the upper thoracic spine demonstrates substantial dural tail (arrow)asso-ciated with spinal meningioma (arrowhead).Volume 233⅐Number 1Dural-Tail Sign⅐57。