Hyperplastic lesions of the larynx. Experience of the Barcelona group

Squamous carcinoma of the larynx arises from pre-existing lesions, the so-called "preneoplastic lesions". Hyperplastic lesions represent a part of their spectrum, from both clinical and biological points of view. On morphologic grounds, the most characteristic feature with prognostic value in the evaluation of preneoplastic lesions is dysplasia. It is not only nuclear alterations that are seen in the process of malignant transformation, the cytoplasmic pattern of cytokeratins changes through neoplastic progression, with a progressive reduction of the molecular weight of the produced species. Dysplasia also associates with gross alterations of the DNA content. This is in agreement with our finding of alterations of genes participating in the control of the cell cycle, p53 and p21(WAF1/cip1). p53 overexpression is detected in non-invasive squamous lesions (even in the absence of obvious dysplasia) and p21(WAF1/cip1) shows a dramatic change in the pattern of expression in dysplastic epithelium compared with the normal. However, not all genes participating in the control of the cell cycle are altered in early lesions. Overexpression of cyclin D1, a common phenomenon in advanced carcinomas, is not likely to participate in the early phases of neoplastic development.