[Electron microscopic and histochemical aspects of the histogenesis and diagnosis of undifferentiated squamous cell carcinoma of the skin].

Basing on the electron-microscopic and histochemical studies of 29 skin tumours with a histological diagnosis of non-differentiated squamous cell carcinoma of the skin it was found that 21 tumour in line with non-differentiated cells contained a small number of tumour cells with ultrastructural and histochemical features of differentiated keratinocytes of the epiderm or from the externa tunica of hair follicles. Analysis of these features, though not identified by routine histological methods, has revealed in 14 cancer cases epidermal histogenesis, in 9 cases cancer originated from the epithelium of hair follicles and in the other 6 cases the tumours contained cells with characteristics of epidermal keratocytes, and of cells from the tunica externa of hair follicles. In 8 out of 29 tumours the authors could not find cells with ultrastructural features of differentiated keratinocytes. The origin of these cancers was determined on the basis of histochemical features of non-differentiated tumour cells corresponding to cambial cells from different epithelial structures of healthy human skin.