atypia

Atypia is a descriptive term used in pathology to describe cells or tissues that show abnormal appearance compared with normal counterparts. The word derives from Greek roots meaning “not in the right form.” Atypia can be seen in a variety of tissues and may reflect reactive, inflammatory, regenerative, or neoplastic processes.

Atypia is distinct from malignancy, though it may be associated with an increased risk of cancer in some contexts. It is usually categorized as cytologic atypia (abnormal cells in terms of size, shape, or staining) or architectural atypia (disordered tissue organization). Cytologic features commonly cited include enlarged and variably shaped nuclei, hyperchromasia (increased staining intensity), irregular nuclear contours, prominent nucleoli, and increased mitotic activity. Architectural changes may involve crowding of cells, loss of normal polarity, and irregular tissue architecture.

Atypia can occur in benign conditions, such as inflammatory or regenerative processes, and in pre-cancerous or malignant conditions. In pathology reports, the presence and degree of atypia help inform risk assessment and management. In some settings, a lesion may be described as “atypical” because its features are insufficient to classify it as benign, dysplastic, or malignant, necessitating further testing or follow-up. Examples in practice include atypical ductal or lobular hyperplasia in breast tissue, atypical endometrial hyperplasia, or atypical squamous cells identified in cervical screening.

Understanding atypia requires clinical correlation and, when needed, additional diagnostic steps to determine whether the atypia represents a benign process, a precursor lesion, or an invasive cancer.