FNA

Fine-needle aspiration (FNA) is a diagnostic procedure in which cells are collected from a suspicious lesion with a thin needle. The material is examined as cytology to help diagnose infections, inflammatory conditions, or neoplasms. Common sites include thyroid nodules, breast lumps, lymph nodes, and salivary glands, but FNA can sample many accessible lesions. The procedure typically uses a 21–25 gauge needle; suction may be applied or a capillary technique used. For deep or poorly palpable lesions, ultrasound or CT guidance improves accuracy. Local anesthesia may be employed, and patients are usually observed briefly afterward. The specimen is smeared on slides, fixed, stained, and evaluated by a cytopathologist or trained cytotechnologist. Rapid on-site evaluation (ROSE) may be available to assess adequacy.

FNA is minimally invasive, generally safe, and cost-effective, with a low risk of complications such as bleeding or infection. Diagnostic accuracy depends on lesion type, sampling technique, and cytopathologist expertise. In some tumors, FNA yields nondiagnostic or indeterminate results because it provides cytology without tissue architecture. In such cases, core needle biopsy or surgical excision may be recommended for histology and ancillary testing. FNA is especially common for thyroid nodules to stratify cancer risk and reduce unnecessary surgery. Contraindications include uncorrected coagulopathy, active infection at the puncture site, or inability to cooperate.