FNA in neck nodes with aspiration or without

Fine-needle aspiration (FNA), including fine-needle aspiration cytology (FNAC) and fine-needle aspiration with thyroglobulin washout (FNA-Tg), plays a pivotal role in the evaluation of neck lymph nodes by providing minimally invasive sampling to assist diagnosis and guide management decisions.

In suspected malignant or unexplained neck lumps, clinical assessment includes careful examination of lymph nodes, noting characteristics such as size, position, consistency, mobility, and associated symptoms, to determine if further investigation with FNA is indicated NICE CKS. Ultrasound guidance optimizes needle placement for sampling suspicious lymph nodes and increases diagnostic yield NICE NG230.

FNA cytology reliably detects malignancy in lymph nodes, with high specificity, but its sensitivity can be variable and is affected by factors such as the size of metastases, presence of micrometastases, and the experience of the operator and cytopathologist Donders et al. 2026. For example, in early-stage oral squamous cell carcinoma with a clinically negative neck, ultrasound-guided FNA cytology demonstrates high specificity but very limited sensitivity (~16%), making it insufficient as a sole modality to exclude occult nodal metastases Donders et al. 2026. Thus, FNA cytology is a valuable adjunct when aspiration is performed on sonographically suspicious lymph nodes but is not definitive when nodes appear normal.

For thyroid cancer, particularly papillary thyroid carcinoma (PTC), FNA with measurement of thyroglobulin in the washout fluid (FNA-Tg) shows excellent diagnostic accuracy in detecting metastatic lymph nodes, especially in patients who have undergone thyroidectomy and have no residual thyroid tissue NICE NG230,Yu et al. 2025. FNA-Tg has a pooled sensitivity of around 94% and specificity of 92% overall, with even higher accuracy in the postoperative setting, making it a highly sensitive and specific tool for assessing lymph node metastases in PTC Yu et al. 2025. It aids in confirming or excluding nodal metastasis and complements cytological assessment NICE NG230,Yu et al. 2025.

Nonetheless, FNA results, whether cytology or thyroglobulin measurements, are not without limitations. False-negative results can occur, particularly in small or poorly differentiated metastases, and false positives may arise from blood contamination or sampling errors Yu et al. 2025,Donders et al. 2026. Therefore, FNA remains an adjunctive diagnostic tool, supplementing clinical and imaging findings rather than replacing histopathological confirmation if malignancy is suspected Yu et al. 2025,Donders et al. 2026.

Recent advances highlight the emerging role of molecular diagnostics, including analysis of long non-coding RNAs (lncRNAs) in FNA samples, which promise to improve sensitivity and specificity in detecting occult lymph node metastases in head and neck squamous cell carcinoma (HNSCC) Lanišnik et al. 2026. However, this molecular profiling is not yet standard clinical practice and requires further validation Lanišnik et al. 2026.

In summary, FNA plays a critical role when lymph node aspiration is performed by allowing cytological or biochemical analysis that aids diagnosis and guides further referral or treatment NICE CKS,NICE NG230,Yu et al. 2025. When aspiration is not performed, clinical assessment and imaging remain essential, but the absence of FNA sampling limits definitive diagnosis of lymph node pathology NICE CKS,Donders et al. 2026. FNA thus functions best as part of a multimodal diagnostic approach in the evaluation of neck lymph nodes.