Atypia

Atypia (from Greek, a + typos, without type; a condition of being irregular or nonstandard) is a pathologic term for a structural abnormality in a cell, i.e. it is used to describe atypical cells.

It may or may not be a precancerous indication associated with later malignancy, but the level of appropriate concern is highly dependent on the context with which it is diagnosed.

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.

In current practice, microscopic analysis of haematoxylin and eosin stained section is the backbone in the diagnosis of breast cancer and other types of cancers. Traditionally, pathologists examine histological slides under a microscope, and make diagnostic decisions. This practice produces results which are subjective. Currently, efforts are being made to develop technology and systems which allow for the use of automated image analysis and machine learning techniques in grading cells which display atypia.

The term atypia is also used dermatologically and can be a precursor to melanoma.

The related concept of dysplasia refers to an abnormality of development, and includes abnormalities on larger, histopathologic scales.

...
Wikipedia