Precision Pathology

February ’10: Inverted Schneiderian Papilloma

A middle-aged patient presented with unilateral nasal stuffiness and fullness, difficulty breathing, rhinorrhea, and epistaxis.

isp

Inverted Schneiderian papillomas are benign lesions which tend to recur and are found most often on the lateral nasal walls. They can invade bone and surrounding structures and are associated with malignant transformation in 5 to 15% of cases. Inverted Schneiderian papilloma occurs about three times more commonly in men than in women and they have a strong association with human papillomavirus (HPV). Local recurrence is related to the extent of the disease, type of surgery performed and length of follow-up.

Histologic examination reveals hyperplastic epithelium invaginating into the fibrovascular connective tissue stroma. Variable proliferation of basal cells, leading to a thickened epithelium, produces a picture resembling transitional epithelium. In areas where squamous maturation is present, koilocytes may be noted in the superficial layers, and they are characterized by having abundant clear cytoplasm and wrinkled nuclei. Mucin droplets or microcysts may be identified within the proliferating epithelium. Cellular atypia and mitoses may be seen.

Treatment: The ideal surgical procedure is to completely remove the lesion. Radiation therapy may be beneficial in recurrent and aggressive lesions. Follow-up includes frequent sinus endoscopy and biopsies if suspicious areas exist.