When going through old examinations in basal pathology, 5th semester medicine, I wondered how, on one hand, dysplasia is defined as being a reversible, non-neoplastic condition, but on the other hand, the term “dysplastic” is used to describe cytologic and histologic changes in benign and malignant tumours. Can you explain this?
Dysplasia denotes the morphological changes associated with pre-malignant and malignant mutations. The term is used to describe pre-malignant changes in an epithelium, i.e. increased cellular proliferation and incomplete differentiation. Dysplasias differ in severity and you may also have dysplasia in an invasive neoplasm : the word therefore does not tell you whether the lesion is premalignant or malignant; or for that sake whether the changes are ‘reversible or irreversible’: therefore the term in current text books has moved to the chapter of neoplasia (from the chapter describing the reversible adaptive changes in tissue). In some tissue like the cervical uterine epithelium, severe dysplasia is termed carcinoma in situ because there is statistical evidence that these changes develop into a carcinoma.
Actually, the term “dysplasia” denotes the changes we also call “cytological criteria of malignancy”, including increased nucleus/cytoplasmatic ratio and pleomorphism. It is caused by mutations or epigenetic changes with the same effects mutations. It was once thought that mild dysplasia was reversible, but this is not the case (although the diseased cells can be sloughed off the surface, thus leaving behind a normal mucosa).