Dysplasia (latin for 'bad form') is an abnormality in the appearance of cells indicative of an early step towards transformation into a neoplasia. It is therefore a pre-neoplastic or pre-cancerous change. This abnormal growth is restricted to the epithelial layer, not invading into the deeper tissue. Though dysplasia may regress spontaneously, persistent lesions must be removed, either with surgery, chemical burning, heat burning, burning with laser, or freezing (cryotherapy). more...
The best know form of dysplasia is the precursor lesions to cervical cancer, called cervical intraepithelial neoplasia (CIN). This lesion is caused by an infection with the human papilloma virus (HPV). Dysplasia of the cervix is almost always unsuspected by the woman. It is usually discovered by a screening test, the pap smear. The purpose of this test is to diagnose the disease early, while it is still in the dysplasia phase and easy to cure.
Dysplasia vs carcinoma in situ vs invasive carcinoma
These terms are related since they represent the three steps of the progression towards cancer:
- Dysplasia is the earliest form of pre-cancerous lesion recognizable in a biopsy by a pathologist. Dysplasia can be low grade or high grade (see CIS below). The risk of low grade dysplasia transforming into high grade dysplasia and, eventually, cancer is low. Treatment is usually easy.
- Carcinoma in situ is synonymous with high grade dysplasia in most organs. The risk of transforming into cancer is high. Treatment is still usually easy.
- Invasive carcinoma, commonly called cancer, is the final step in this sequence. It is a disease who, when left untreated, will invade the host (hence its name) and will probably kill him. It can be often, but not always, be treated successfully.
Metaplasia is a situation where cells have changed from their original mature differentiated type into another mature differentiated cell type as an adaptive response to exposure to chronic irritation, or to a pathogen or carcinogen. It also occurs where one normal cell type changes into another normal cell type as in the cervix where squamous epithelium on the exo-cervix changes to normal columnar epithelium in the endo-cervix. This area is also known as the transformation zone and is the location of many dyplastic lesions thus the sampling of this area during a pap test is critical. Metaplasia is distinct from dysplasia because in a dysplastic cell these changes have become encoded into the genome and so are heritable or passed on to daughter cells during cell replication.
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