cytodiagnosis

Cytodiagnosis, or cytopathology, is the branch of diagnostic pathology that relies on microscopic examination of individual cells or small clusters to reach a diagnosis. It emphasizes cellular morphology rather than tissue architecture and often uses cells obtained from body fluids or tissue sampling.

Specimens are obtained by exfoliative cytology (scrapings, brushings, urine, sputum) or by aspiration (fine-needle aspiration cytology, FNAC) of masses or organs, as well as from body fluids such as cerebrospinal, pleural, and ascitic fluids. The material is prepared as smears or monolayer preparations, fixed and stained with methods such as Papanicolaou or May-Grunwald-Giemsa, to reveal nuclear and cytoplasmic features.

Cytodiagnosis is used for cancer screening and diagnosis (e.g., cervical cancer screening with the Pap test, evaluation of thyroid nodules, breast lumps, lymph nodes), infectious diseases (viral infections, tuberculosis), and inflammatory or metabolic disorders. It provides rapid preliminary information and can guide further testing or treatment, and FNAC is particularly favored for accessible lesions due to minimal invasiveness.

Limitations include sampling error and the absence of tissue context, which may hinder assessment of invasion or tumor architecture. There can be overlap between benign and malignant cytomorphology, and interpretation depends on operator experience. Artifacts, degenerated cells, and reactive changes can complicate diagnosis; cytodiagnosis is usually integrated with histology and clinical data.

Historically, cytology emerged in the late 19th and early 20th centuries and was advanced by Papanicolaou’s cervical smear test. Today cytodiagnosis is a routine component of diagnostic pathology worldwide, with standardized reporting systems for cervical and other cytology specimens.