Squamous cell carcinoma arising in epidermal and human papillomavirus associated cysts: report of three cases

Objectives. The clinical-pathological features of squamous cell carcinoma (SCC) arising in cutaneous cysts has been studied. Methods. We report two cases of SCC arising in epidermal cyst (EC) and one case in human papilloma virus associated cyst (HPAC). Results. In the first EC case, a 88-year-old man presented a cystic right zigomatic mass. Histopathology revealed a cyst lined by stratified squamous epithelium in continuity with invasive keratinizing SCC. In the second EC case, a 96-year-old man presented with a 1.5x1 cm nodular lesion localized at the helix of the right ear. Histopathology showed the typical cystic wall of an EC with transition to invasive keratinizing SCC. Finally, a 86 year-old woman presented with a perineal cystic nodule 1.5 cm in diameter. The wall showed varying degrees of papillomatosis, hypergranulosis, parakeratosis with dysplastic and koilocytic changes. Areas of in situ and invasive SCC were found. Human papillomavirus (HPV) 16 was detected. Conclusions. SCC arising in an EC may be diagnosed only with the support of an accurate histopathological documentation in order to exclude mimics. Regarding HPAC, the site, the malignant transformation and the finding of HPV 16 type, may be considered features of an extraordinary rare case.