Paper I
Question
Dysplasia
Answer
Dysplasia is a premalignant, disordered pattern of epithelial cell growth characterized by loss of uniformity of individual cells and loss of their normal architectural orientation, without invasion through the basement membrane.
Features
- Cellular pleomorphism (variation in cell size and shape)
- Nuclear hyperchromasia and increased nuclear:cytoplasmic ratio
- Increased and sometimes abnormal mitotic figures, which may appear at any level of the epithelium (not just the basal layer)
- Architectural disorganization — loss of normal cell polarity/orientation
Classification
- Graded as mild, moderate, or severe, based on the proportion of epithelial thickness involved
- Carcinoma in situ: Severe dysplasia involving the full thickness of the epithelium, still confined by an intact basement membrane (no invasion)
Clinical significance
- Considered a premalignant/precancerous lesion
- Mild dysplasia may be reversible if the causative stimulus is removed; severe dysplasia/carcinoma in situ carries a high risk of progression to invasive carcinoma if untreated
- Examples: cervical intraepithelial neoplasia (CIN), Barrett oesophagus-associated dysplasia, actinic keratosis