Imaging of sino-nasal inverted papilloma: How can we emphasize the usefulness of the “striated pattern” sign?

Abstract

Background: Inverted papilloma (IP) is an uncommon sino-nasal neoplasm with potentially distinctive MRI and CT features. The MR "striated" imaging pattern has been reported as a valuable MR imaging feature of IP. The purpose of this study was to validate the usefulness of this sign using detailed criteria of the sign itself. Results: All imaging findings were described for 16 patients in descriptive pattern. The nasal involvement showed highest prevalence followed by the maxillary sinus. The bony changes include remodeling and defects (n = 6), remodeling only (n = 4), and None (n = 6). Changes were severe 1/10, moderate in 3/10, and mild 5/10. Focal hyperostosis was seen in six. A striated pattern was "diffuse" in all 16 (100%) of the IPs; it followed a certain direction in all 16 patients: divergent (n = 6), convoluted (n = 2), and parallel (n = 8). Divergent growth from focal hyperostosis was seen (n = 4). Visibility of the sign was superior in T2 images (n = 11), superior in enhanced images (n = 3), and equal in both (n = 2). Conclusions: The striated pattern is a reliable MR imaging feature of sino-nasal IPs. Validity and usefulness of this sign can be emphasized by defining parameters of the signs itself including the following: diffusivity, direction of striations and relation to hyperostosis, and comparing visibility in both T2 and GAD-enhanced images, as well as combining this imaging signature with remolding bony changes < 1.5.

Evaluation of Unilateral Sinonasal Lesions

“…In the study of Eid and Eissa [5], nasal involvement was the most common type, occurring in ten cases, in eight patients, with varying degrees of nasal and sinus involvement, and only two patients with purely unilateral nasal disease; One depicts a nasal mass between the inferior and middle turbinates, while another is epicentered on the traditional location of the lateral nasal wall, opposite the middle meatus. In one example of bilateral bi-nasal illness, the nasal lesions were predominantly big with limited frontal sinus extension.…”

A practical overview of CT and MRI features of developmental, inflammatory, and neoplastic lesions of the sphenoid body and clivus

“…Calcifications within papilloma are rare. At MRI, this tumour appears isointense to muscle on T1W images [ 73 ], and it may show a typical “cerebriform” pattern on T2W and CE-T1W images, thanks to the alternating lines of high and low SI. The diffusion pattern is non-specific and does not reliably allow radiologists to separate the inverted papilloma from malignant lesions [ 73 ]; sometimes, intralesional carcinoma foci usually can be observed as areas of lower ADC values [ 74 ].…”

“…At MRI, this tumour appears isointense to muscle on T1W images [ 73 ], and it may show a typical “cerebriform” pattern on T2W and CE-T1W images, thanks to the alternating lines of high and low SI. The diffusion pattern is non-specific and does not reliably allow radiologists to separate the inverted papilloma from malignant lesions [ 73 ]; sometimes, intralesional carcinoma foci usually can be observed as areas of lower ADC values [ 74 ]. Differential diagnoses : sphenoid sinus mucocele, which does not show CE of the internal component (see “ Mucocele ” paragraph); spheno-choanal polyp, a unilateral inflammatory soft tissue mass arising from sphenoid sinus and extending through its drainage ostium and spheno-ethmoidal recess towards the choana and nasopharynx.…”

Sinonasal Inverted Papilloma Extirpation by Endoscopic Approach: a Case Report

“…sinus and hyperostosis feature with the tendency to grow on the tumor which is also known as "cone shape appearance" was also found. [9][10][11][12] Surgical approach is the treatment of choice for inverted papilloma including lateral rhinotomy, maxillectomy, degloving, and mass extirpation via endoscopy. The principle of inverted papilloma treatment is total tumor removal without residue to prevent relapse.…”