Diagnostic Tests– Lymph Node Biopsy

A lymph node biopsy is performed to determine whether lymph node enlargement is due to infection, malignancy, or another underlying condition. The choice between a needle biopsy and an excisional biopsy depends entirely on the clinical suspicion and the characteristics of the lymph node. Proper selection is essential because certain conditions require specific types of tissue sampling to achieve an accurate diagnosis.


A needle biopsy is the correct choice when an infectious cause of lymphadenopathy is suspected. Infections such as tuberculosis, fungal infections, or bacterial infections (including Staphylococcus) can be diagnosed using needle aspiration because this method provides enough material for microbiologic studies. Clinically, infectious lymph nodes are often warm, tender, red, and sometimes fluctuant, reflecting inflammation. Because diagnosing infection does not require assessing the full architecture of the lymph node, a needle biopsy is usually sufficient.


An excisional biopsy is the best and most accurate test when lymphoma is suspected. Lymphoma requires examination of the complete lymph node architecture, which cannot be obtained through a needle biopsy. In fact, using a needle biopsy to diagnose lymphoma is a frequent wrong answer in exams because individual lymphocytes can appear normal on cytology, leading to missed diagnoses. Lymph nodes involved in lymphoma are typically nontender, firm, and not warm or red, distinguishing them from infectious nodes. When these features are present, an excisional biopsy is the appropriate diagnostic test.