[Differential diagnosis of basalioma and metatypical skin cancer]

The WHO histological classification of skin tumors (Geneva, 1980) has first distinguished a new nosologic variety of skin carcinoma, metatypic carcinoma (MTC) being intermediate between basalioma and squamous cell carcinoma. Separation of MTC from the group of basaliomas is important prognostically because this tumor is capable of metastasizing, whereas MTC diagnosis is difficult because it simulates basalioma clinically and morphologically. The study of the mitotic regimen in 13 cases of MTC and 20 cases of basalioma showed this method to be adequate for differential diagnosis of these tumors. The values of the mitotic regimen in MTC always differed from similar values in basalioma: the mitotic activity, the specific content of dividing cells at the stage of metaphase, and the rate of pathologic mitoses increased considerably, there appeared multipolar and monocentric mitoses, bridges, three-phase metaphases.