Radial intralesional linear calcifications and focal hyperostosis: key points for diagnosis, extension and point of origin identification of sinonasal inverted papilloma.

Sinonasal inverted papilloma (IP) often appears as a unilateral sinonasal soft-tissue mass with varying enhancement, often accompanied by bone remodelling, intralesional calcifications, focal hyperostosis, and cone-shaped bone thickening (observed in 60 to 80% of cases) (1,2). A non-contrast sinonasal CT scan may reveal a soft tissue polypoid mass that closely resembles inflammatory polyps (Figure 1 A-D). While hyperostosis is recognized as a marker of the tumor's point of origin (1), intralesional calcifications are less frequently described but may offer valuable insights. Early studies, such as those by Lund and Lloyd (1984), highlighted the presence of intralesional calcifications as a distinct feature of inverted papilloma, a finding later supported by studies emphasizing the role of bone morphogenic proteins in calcification development (4-7).