Amin, Sara E.

Inverted papilloma (IP) is a benign neoplasm of the nasal cavity and paranasal sinuses, known for its variable risk of recurrence and potential for developing carcinoma. Emerging evidence has shown high rates of activating EGFR mutation, and a smaller subset is associated with low-risk human papillomavirus (lrHPV). While certain morphologic features, including an inverted growth pattern, are well-established, the presence of condylomatous features, such as large fungating lesions with thick undulating surface epithelium, hyperkeratosis, cytoplasmic clearing, raisinoid nuclei, and binucleation (koilocytic changes) in low-risk HPV-associated IP suggests that these tumors may be a distinct subtype of sinonasal papilloma (SP) with features similar to low-risk HPV-associated anogenital condylomas. This study presents a series of SP with condylomatous morphology and explores the association with lrHPV, the clinicopathologic features, and the rates of carcinoma development. In total, 17 cases of SP exhibiting condylomatous morphology were retrospectively identified. We performed lrHPV and high-risk HPV (hrHPV) RNA in situ hybridization and p16 immunohistochemistry and gathered detailed clinical and pathologic data along with treatment, disease follow-up, and outcomes. These condylomatous papillomas almost all developed in active smokers, were large, were primarily located in the nasal cavity (47%), and showed frequent transformation to invasive squamous cell carcinoma (29%). This malignant transformation rate is much higher than what has been reported for inverted, exophytic, and oncocytic papillomas. The tumors were almost uniformly associated with transcriptionally-active lrHPV (94%) and were consistently negative for p16 and hrHPV. This study shows that a subgroup of IPs with condylomatous morphology have a predilection for the nasal cavity, strong association with lrHPV, and high rates of carcinoma. These findings support the concept that these tumors are a distinct (fourth) type of SP with a higher risk of malignant transformation.

DEK::AFF2 fusion nonkeratinizing squamous cell carcinoma (NKSCC) is an emerging entity in the sinonasal tract, temporal bone, and skull base. However, the clinical behavior of these tumors has not been well studied. Here, we report the largest cohort of DEK::AFF2 carcinomas to determine if morphology, mitotic rate, and/or Ki-67 IHC are associated with patient outcomes, including a comparison with high-risk human papillomavirus (HPV)-associated and independent patients. We solicited cases of molecularly or AFF2 immunohistochemistry (IHC) proven DEK::AFF2 SCC from surgical pathologists to collect patient demographic, clinical, and outcome data. Using representative H&E slides, we characterized the morphology and counted mitoses. Ki-67 immunohistochemistry was performed. We also compared the DEK::AFF2 survival rates to those in a cohort of AFF2 IHC-negative HPV-associated and HPV-independent SCC. DEK::AFF2 carcinomas most commonly arose in the nasal cavity (13/30, 43%), and the average number of recurrences was 1.8 (range: 0 to 10). At the last follow-up, most patients were disease free (19/30, 63%) or were alive with disease (9/30, 30%). There was an average mitotic rate of 2 per 2 mm2 (range: 0 to 9) and Ki-67 proliferation rate of 26% (range: 3% to 60%). Local recurrence was common, but morphology, mitotic activity, and Ki-67 index were not associated with recurrence or survival. On Kaplan-Meier survival analysis, DEK::AFF2 patients had lower disease-free survival but otherwise had similar outcomes to conventional SCC patients. Our multi-institutional study shows that local recurrence is common in DEK::AFF2 fusion nonkeratinizing SCC patients, but patients have survival rates similar to conventional SCC. Despite showing a range of different features and proliferation rates, traditional grading by morphology, mitotic rate, and/or Ki-67 activity does not seem to be predictive of outcome.