Abstract
Inverted (Schneiderian) sinonasal papilloma (ISP) is a neoplasm derived from mucosa of the sinonasal tract characterized by local aggressive growth, a tendency to recur and an association with sinonasal carcinoma. The etiology of ISP remains unclear. Recently, identical mutations in exons 19 and 20 of the oncogene EGFR were reported in ISP and ISP-associated sinonasal carcinoma. Nevertheless, it remains unclear whether recurring ISPs show identical EGFR mutations at different time points or whether these mutations are identical throughout the respective ISP sample. We used Sanger sequencing to test 60 formalin-fixed paraffin embedded ISP samples from 40 patients regarding mutations in exons 19 and 20 of EGFR—together with exon 15 of BRAF. Overall, 32 samples of 22 patients showed a mutation in EGFR exon 20, whereas 28 samples of 18 patients showed none. No mutation in EGFR exon 19 was found in any sample. Four samples of four patients showed a BRAF exon 15 mutation. Interestingly, samples of four patients exhibited genetic heterogeneity, enabling us to report this in ISP for the first time.
Highlights
Inverted sinonasal papilloma (ISP) is a neoplastic proliferation arising from the sinonasal tract mucosa with predominantly inverted growth [1]
epidermal growth factor receptor (EGFR) mutations have been hitherto demonstrated in 38 to 88% of ISPs [3, 16] and in 50 to 88% of ISPassociated squamous cell carcinomas (SSCCs) [10, 16]: Cabal et al found EGFR exon 20 mutations in 38% (7/18) of ISPs and in 50% (6/12) of ISPassociated SSCCs, while EGFR exon 20 mutations in ISPunassociated SSCC occurred in only 5.3% (1/19) [16]
Sasaki et al reported EGFR mutation in 100% (9/9) of ISPs and 83% (10/12) of ISPs associated with SSCC, the vast majority being exon 20 insertions
Summary
Inverted sinonasal papilloma (ISP) is a neoplastic proliferation arising from the sinonasal tract mucosa with predominantly inverted growth [1]. ISPs are mostly located in the nasal cavity and the maxillary sinus [2]. They often recur and may grow locally destructive [3]. The association with carcinoma is stronger for ISP than for exophytic papillomas [1]. In about 1.9 to 27% of ISPs, sinonasal squamous cell carcinomas (SSCCs) are found, the majority being synchronous tumors [4]. The etiology of ISP is virtually unknown. Exposure to organic solvents has been reported as a risk factor, and the importance of HPVinfection has been discussed, albeit controversially [2, 4]
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