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Atypia: Etymology: Gk, a + typos, without type; a condition of being irregular or nonstandard. 
Atypia can be caused by an infection or irritation if diagnosed in a Pap smear, for example. In the uterus it is more likely to be precancerous. For example, already differentiated, specialised cells such as epithelia displaying "cellular atypia" are far less likely to become problematic [cancerous/ malignant] than are myeloid progenitor cells of the immune system. The 'further back' in an already specialised, differentiated cell's lineage, the more problematic cellular atypia is likely to be. This is due to the conferring of such atypia to progeny-cells further down the lineage of that cell type.
The term atypia is also used dermatologically and can be a precursor to melanoma.
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