[Verrucous carcinoma and carcinoma cuniculatum--forms of squamous cell carcinoma?].

The morphology of verrucous carcinoma (Ackerman tumor) and carcinoma cuniculatum is described and the problems of diagnosis and classification are discussed on the basis of the relevant literature. Both lesions are closely related aggressive proliferations of squamous epithelium of the skin and mucous membranes. Verrucous carcinoma exhibits an exophytic as well as endophytic growth pattern on a broad front; dissociated invasive growth, however, is usually absent. Carcinoma cuniculatum is similar; however, conspicuous deep duct-like formations and keratin-filled sinuses are formed. Clinically, these tumors appear to be malignant. Histological evaluation often results in the tumors being underestimated and a false diagnosis of a benign papillomatous lesion or pseudoepitheliomatous hyperplasia being made. The necessity is stressed of a thorough histological investigation of the tumors in multiple sections and of a search for dissociated invasive growth. It is suggested that cases without this feature should not be termed carcinoma but should rather be given a more descriptive diagnosis such as verrucous hyperplasia or proliferation. Cases with clear invasive growth should be classified as papillary squamous cell carcinomas (grade I). A detailed characterization should be given in addition. Although both tumors show features of viral lesions, it has so far not been possible to demonstrate viruses by electron microscopy or structural antigens of human papilloma viruses (HPV). Both clinical picture and histology must be taken into consideration when diagnosing these two tumors ("clinicopathologic entity"). Close cooperation between the clinician and the pathologist is desirable for individual assessment of these lesions as regards classification and therapy.