CASE 18685 Published on 10.09.2024

Key features of sinonasal inverted papilloma: Focal hyperostosis/cerebriform pattern

Section

Head & neck imaging

Case Type

Clinical Case

Authors

Rodrigo Sánchez Vallejo, Esther Granell Moreno

Neuroradiology Division, Department of Radiology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain

Patient

52 years, male

Categories
Area of Interest Ear / Nose / Throat ; Imaging Technique CT, MR
Clinical History

A 52-year-old male smoker presented with a 4-month history of right-sided nasal obstruction and rhinorrhoea. No other symptoms; particularly no epistaxis or anosmia. Nasal endoscopy revealed a large polypoid mass which appeared to arise from the middle meatus, filling the entire right nasal fossa and extending into the cavum.

Imaging Findings

Contrast-enhanced computed tomography (CT) and pre and post-contrast magnetic resonance (MR) imaging of the sinonasal cavity were performed.

CT (Figures 1a and 1b) revealed a mildly enhancing soft tissue density mass occupying the right maxillary sinus and ipsilateral nasal fossa, along with a focal hyperostosis located at the maxillary roof. No bony destruction or intralesional calcifications were found.

MR (Figures 2a and 2b) confirmed the presence of a large expansile lobulated mass, arising from the superior wall of the right maxillary sinus with extension into the lateral nasal wall and anterior ethmoidal cells, obstructing the anterior ostiomeatal complex.

The mass showed an iso-intense signal compared to muscle, exhibiting a convoluted cerebriform pattern (CCP), characterised by alternating hypointense and hyperintense bands, which were best visualised on T2-weighted images. No extension beyond the sinus was observed.

Histopathology confirmed the final diagnosis.

Discussion

Inverted papilloma (IP) is the most common benign epithelial sinonasal neoplasm (50% to 80% of all papillomas) [1]. It exhibits locally aggressive behaviour, a tendency to recur, and potential for malignant transformation into squamous cell carcinoma (SCC), with synchronous or metachronous malignancy rates of 4% and 7%, respectively [2,3]. Histologically, IP display an endophytic growth pattern, in which surface epithelial cells invaginate into the underlying stroma [3]. The common site of origin is the lateral nasal wall and the maxillary or ethmoidal sinus [3,4].

The etiopathogenesis is not fully understood; however, chronic inflammation, viral infections, environmental exposure, and angiogenic factors have been implicated [2,3,5].

IP occurs two to five times more often in men than in women, usually in the 5th and 6th decades. Symptoms are nonspecific, including unilateral nasal obstruction, epistaxis, rhinorrhoea, anosmia, and headache. Endoscopic examination reveals a reddish-grey lobulated tumour [3].

CT appearance of IP is nonspecific, showing a unilateral sinonasal soft-tissue density mass, with variable enhancement, often accompanied by bone remodelling and intralesional calcifications (20%) [3,6]. Additionally, focal hyperostosis is frequently associated, which can predict a tumour attachment site, with a high positive predictive value of 89% [4].

MR shows a characteristic convoluted cerebriform pattern (CCP), reflecting the tumour’s histopathologic architecture. Though the CCP is a reliable MR feature (accuracy of 89%), it can also be seen in co-existing IP with SCC or other malignant tumours; therefore, the final diagnosis relies on histopathology [3,7,8]. The presence of bone destruction on CT and the absence of CCP, along with restricted diffusion and necrosis on MR, may indicate malignant transformation or co-existent SCC [3,7,9].

The proper surgical approach selection (endonasal endoscopic, external, or combined) depends on accurate preoperative imaging assessment, determining the tumour attachment site and extension.

Recurrences occur within 2 years of surgery, with rates between 8.5% and 40%, mostly attributable to incomplete removal. Therefore, the complete resection of the IP attachment site is needed to avoid recurrences. Imaging follow-up is recommended for 3–5 years [3,4].

IP malignant transformation may require extensive surgical resection, along with radiation or chemotherapy [3,9,10].

Teaching Points

  • Sinonasal IP is characterised by locally aggressive behaviour, frequent recurrences, and potential for malignant transformation.
  • Focal hyperostosis highly correlates with the origin site of IP.
  • CCP is a distinctive MR feature of IPs, but it cannot certainly distinguish between benign IP from IP concomitant with SCC or other malignant tumours.

All patient data have been completely anonymised throughout the entire manuscript and related files.

 

Differential Diagnosis List
Antrochoanal polyp
Sinonasal polyposis
Sinonasal inverted papilloma
Sinonasal carcinoma
Final Diagnosis
Sinonasal inverted papilloma
Case information
URL: https://eurorad.org/case/18685
DOI: 10.35100/eurorad/case.18685
ISSN: 1563-4086
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