Oral squamous papilloma (OSP) is a common benign lesion of the oral mucosa that is induced by the human papillomavirus. To investigate the clinicopathological characteristics of OSP, we selected 135 patients diagnosed at the Seoul National University Dental Hospital. OSPs occurring in Koreans had a slight female predilection, with the male to female ratio being 1:1.6. The age ranged from 4 to 80 years old (average age: 47 years). The most frequent location was the soft palate (43.7%), followed by the tongue and gingiva. 11.1% of all patients presented with pain. There have been no reported cases of recurrence. On microscopic examination, two‐thirds of the lesions were parakeratinized, with almost all cases (99%) containing the koilocytes. In conclusion, there were no significant differences between the clinicopathological features of OSP in Korean and findings from previous studies

Oral squamous cell papillomas(OSCPs) showed various features in their etiology, histology, and prognosis. Therefore, it is necessary to diagnose differentially according to their pathological examinations. In the present study total 14 cases of OSCPs were evaluated and characterized to be three types of OSCPs, i.e., papillary papilloma, verrucous papilloma, and inverted papilloma. The present study demonstrated that among 14 cases of OSCPs papillary papilloma (n＝6) showed the typical papillary projection of squamous epithelium with severe acanthosis of upper spinous layer cells, accompanying frequent nuclear vacuolization. And verrucous papilloma (n＝7) showed the diffuse acanthosis of whole spinous layer cells with severe basal hyperplasia, resulted in the thick squamous epithelium exhibiting verrucous surface and irregularly ingrowing rete pegs. One case of inverted papilloma showed the typical ingrowth of basal layer cells deeply into underlying connective tissue, resulted in the formation of multiple fissures on the surface area. The present study also revealed the predominant nuclear vacuolization suspicious for viral infection in papillary papilloma, and also heavy smoking history in the verrucous papilloma. On the other hand, as the epithelium of inverted papilloma ingrew into the underlying deep connective tissue up to the muscular layer, it is supposed that the inverted papilloma has a potential of basal layer proliferation strong enough to invade the protecting barrier of underlying connective tissue, or that the underlying connective tissue was too weak to prevent the ingrowth of basal layer epithelium. Taken together, because the OSCPs show heterogenous origins and variable pathological prognosis, it is suggested that the OSCPs should be differentially diagnosed at least into three types, i.e., papillary papilloma, verrucous papilloma, and inverted papilloma.