Dysplasia
This article covers Dysplasia, a pre-cancerous change in cellular structures. For details on Hip dysplasia, a clinical condition affecting the hip joint (especially in dogs), please see the article on Hip dysplasia.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).
The best known form of dysplasia is the precursor lesions to
cervical cancer, called
cervical intraepithelial neoplasia (CIN). This lesion is sometimes 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.
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 which, when left untreated, will invade the host (hence its name) and will probably kill them. It can 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.
*Dorland's Illustrated Medical Dictionary, 1985, W.B. Saunders Company, Philadelphia
*http://www.gynalternatives.com/treatment.htm
*http://www.cwhn.ca/resources/faq/cervProcTreat.html#5
*
Fibrous dysplasia*
Cervical conization 
