[Biological behavior of epithelioma cuniculatum]

E. cuniculatum is a low-grade squamous cell carcinoma belonging to the group of Ackerman's verrucous carcinoma. The papillomatous, cauliflower-like tumor slowly grows over many years without forming metastases. Histology reveals deeply invaginated proliferations with organoid epidermal organization and central parakeratotic horny crypts. Only the basal and suprabasal cell layers show histological features of malignancy; the basal membrane, however, remains intact. Radiation therapy as well as repeated operations may provoke anaplastic transformation into metastases. We discuss the therapy and differential diagnosis of these tumors and report on two own cases.