Cryotherapy of carcinoma in situ and microinvasive carcinomas

Carcinoma in situ and microinvasive tracheobronchial carcinomas are well defined histological entities. They are characterized by histological changes of the respiratory mucosa which is generally considered to be the site of origin of bronchial cancer, namely malpighian metaplasia, with varying degrees of cellular changes giving the appearance of dysplasia. The criteria which distinguish a carcinoma in situ from dysplasia have been proposed by Black and Akermann [1]. They include the loss of normal cellular differentiation, absence of ciliated and mucous cells, disruption of epithelial architecture and cytonuclear and mitotic abnormalities throughout the entire thickness of the abnormal epithelium. Carcinoma in situ is generally associated with an increase in the thickness of the epithelium, very often with hyperacanthosis [2]. As a rule the borderline between the lesion and normal or dysplastic epithelium is well defined. The adjoining glands and excretory tubes may be invaded with malignant cells whilst preserving the basal membrane.