Magnetic Resonance Imaging Findings of Inverted Papilloma: Differential Diagnosis with Malignant Sinonasal Tumors

Abstract

A columnar pattern is a reliable MRI indicator of IP and reflects its histological architecture (positive predictive value of 95.8%). The combination of this finding with the absence of extended bone erosion allows for the confident discrimination of IPs from MTs.

Sinonasal Inverted Papilloma: Value of Convoluted Cerebriform Pattern on MR Imaging

“…Our study also showed that the contrast-enhanced T1-weighted images were superior to the T2-weighted images in the detection of a CCP (30 of 30 [100%] versus 28 of 30 [93%]), as reported by Maroldi et al 19 Furthermore, the quality of contrast-enhanced T1-weighted images was at least as good as that of T2-weighted images in all of the patients with IP. The superiority of the contrast-enhanced T1-weighted images might be attributed to the vascular nature of the tumor, which would become more conspicuous after the injection of contrast material.…”

“…[3][4][5][6][7][8][9][10][11][12] Although CT and MR imaging are useful for preoperative assessment of sinonasal IP, differentiation of IP from other malignant sinonasal tumors is often difficult because of a significant overlap of the imaging features. [13][14][15][16][17][18][19] Barnes et al 20 described a distinctive gross mucosal morphology of IP, a so-called convoluted cerebriform pattern (CCP), which can be reflected on MR imaging by the characteristic alternating hypointense and hyperintense bands on T2-weighted and contrast-enhanced T1-weighted images, as reported by Ojiri et al 17 and supported by Maroldi et al 19 years later. It would be useful for planning therapeutic strategies if the CCP on MR imaging can suggest the preoperative diagnosis of IP, because more aggressive surgical approaches would be needed for IPs concomitant with SCC and other malignant sinonasal tumors.…”

“…17 However, they did not evaluate the prevalence of this MR imaging feature in other malignant sinonasal tumors. In their study with 23 patients with IP, Maroldi et al 19 coined the term "columnar pattern" and observed it in 16 patients (69.5%) on T2-weighted images and 23 patients (100%) on contrast-enhanced T1-weighted images. In their study, this columnar pattern was identified in only 1 (4.3%) of 23 other malignant sinonasal tumors on both T2-weighted and contrast-enhanced T1-weighted images.…”

“…[11][12][13][14][15][16][17][18][22][23][24] However, differentiation of IP from other malignant sinonasal tumors by analyzing the internal characteristics on radiologic imaging is often difficult, because there is a significant overlap between those diseases. 15,16,19 IP is seen pathologically as a vascular mass with prominent mucous cyst inclusions interspersed throughout the epithelium and a high intracellular glycogen content. 3,20 The name is a descriptive term of the histology that shows inversion of the surface epithelium into the underlying stroma rather than exophytic proliferation.…”

“…5,15 On physical examination, IP presents as a polypoid growth covered by a convoluted cerebriform mucosa, called a CCP, as described by Barnes et al 20 This gross morphology, created by the juxtaposed epithelial and stromal layers, results in a peculiar pattern on MR imaging, manifesting as the alternating hypointense and hyperintense bands, which has been described under the various terms. 13,17,19 Yousem et al 13 used the term "septate striated appearance" and noticed it in 5 (50%) of 10 patients with IP on T2-weighted images. However, the researchers did not impart much importance to it because it was also seen in 2 of 8 other sinonasal malignancies.…”