Characteristic bright signal of parotid pleomorphic adenomas on T2-weighted MR images with pathological correlation

An algorithm for preoperative differential diagnostics of parotid tumours on the basis of their dynamic and diffusion-weighted magnetic resonance images: a retrospective analysis of 158 cases

“…Clinical experience suggests that the previously proposed cut-off values for T peak (120, 210 or 240 s) and WR (10%) [9,18,20,21] are not accurate enough to distinguish malignant tumours from pleomorphic adenomas. Moreover, the TICs for some parotid malignancies resemble those traditionally assigned to pleomorphic adenomas [20]. Therefore, some authors postulated that these two types of lesions should be distinguished on the basis of their ADC values determined on diffusion-weighted MRI.…”

“…However, further research on the cut-off values for T peak and WR providing maximum accuracy in the differential diagnostics of these three groups produced conflicting results. While there is a consensus with regards to the cut-off values for T peak and WR that accurately distinguish parotid malignancies from Warthin tumours (T peak = 60 s and WR = 30%) [9,18,20,21], the differential diagnostics of pleomorphic adenomas and malignant lesions is still a challenge. Clinical experience suggests that the previously proposed cut-off values for T peak (120, 210 or 240 s) and WR (10%) [9,18,20,21] are not accurate enough to distinguish malignant tumours from pleomorphic adenomas.…”

“…The time intensity curves (TICs) for two most common histological types of benign parotid lesions, pleomorphic adenomas and Warthin tumours, differ from those for parotid malignancies [1,[7][8][9][10][11][12][13]19]. A few studies applying this knowledge in differential diagnostics of parotid tumours produced promising results [18,20,21]. However, this evidence, originating from relatively small studies of patients with pleomorphic adenomas, Warthin tumours and parotid malignancies, was not confirmed in routine clinical practice [5].…”

“…However, this evidence, originating from relatively small studies of patients with pleomorphic adenomas, Warthin tumours and parotid malignancies, was not confirmed in routine clinical practice [5]. Moreover, some empirical data imply that parotid malignancies are not homogeneous in terms of their presentation on dynamic MRI, and therefore some of them may be misdiagnosed as pleomorphic adenomas [20].…”

37 Recurrent Pleomorphic Adenoma

“…Typically, imaging studies will reveal a lobulated mass with post-contrast enhancement and a bright T2-weighted signal without local tissue invasion [6]. The bright signal on T2-weighted images corresponds to myxoid areas and is distinctive for pleomorphic adenoma [7]. Alternately, a hypointense signal on T2-weighted or STIR (short tau inversion recovery) images is indicative of hyalinization [8]; when in combination with an ill-defined or infiltrative border [5] the findings are suggestive of degeneration and subsequent malignant change.…”