Angiectatic nasal polyps with pleomorphism ‒ a diagnostic pitfall

Objective: To generalise the features of PANP in case of potential clinical and pathological pitfall of diagnosis. Methods: Thirteen patients diagnosed as PANP were retrospectively analyzed in the Pathology Department of Capital Medical University from August 2014 to December 2019. Immunohistochemical staining with CD34, CK, Vim, Calponin, Ki67, Bcl-2, and STAT-6 was performed with envision-two steps method. Results: PANP is a benign tumor presenting with gross variegated tan to gray soft fleshy tissue with foci of obvious hemorrhage and necrosis. The imaging shows internal heterogeneous hyperintensity with a peripheral hypointense rim while postcontrast images display a strong nodular and patchy enhancement. Vimentin (Vim) stain was consistently positive, while negative for CD34, STAT-6 and Bcl-2 (focal positive in two cases). Calponin and CK stain was positive in nine cases, respectively. Conclusion: PANP is a clinically rare tumor which may simulate malignancy lesion. Recognizing of characteristic features in these thirteen patients would be beneficial to avoid misdiagnosis and unnecessary aggressive treatment. Level of evidence: This work was Level 2 of evidence according to the Guide for Authors