FNAhistologia

FNA histologia is the histological analysis of material obtained by fine-needle aspiration. It emphasizes not only cytology smears but also the preparation of material into cell blocks suitable for paraffin embedding, enabling tissue architecture assessment and immunohistochemical staining. It complements conventional cytology for diagnostic accuracy and ancillary testing.

FNA is performed with a thin-gauge needle under palpation or ultrasound guidance. Material is used to prepare conventional cytology smears, and residual material can be processed into a cell block by clotting or plasma-thrombin methods, fixed in formalin, embedded in paraffin, and sectioned like a histology specimen. Immunohistochemistry and molecular tests may be performed on cell blocks; rapid on-site evaluation (ROSE) may improve sample adequacy.

Applications include lesions in the thyroid, salivary glands, breast, lymph nodes, and lungs. FNA histology aids diagnosis, subtyping, and treatment planning, particularly when a patient may avoid more invasive procedures. However, its effectiveness depends on obtaining sufficient material and representative sampling. Some lesions yield limited architectural detail in cell blocks, in which case a core needle biopsy or excisional biopsy may be preferred. The technique is minimally invasive and generally considered safe, often used as an initial diagnostic tool in focal diseases.