Overview
Lymph Node Fine Needle Aspiration (FNAC) is a minimally invasive diagnostic procedure used to evaluate lymphadenopathy and determine its cause. This technique involves using a thin needle to aspirate cellular material from lymph nodes for cytological examination. Lymph node FNAC is particularly valuable for rapid diagnosis of lymphadenopathy and helps distinguish between reactive, inflammatory, and neoplastic conditions.
Lymph node FNAC is crucial for the evaluation of lymphadenopathy, which is a common clinical finding. The procedure helps identify malignant lymphomas and metastatic disease while avoiding unnecessary surgery for reactive conditions. It is particularly valuable in the evaluation of peripheral lymphadenopathy and helps guide further management decisions. The procedure is cost-effective, safe, and provides rapid results compared to excisional biopsy.
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Indications
Evaluation of palpable lymph nodes in cervical, axillary, or inguinal regions
Lymph nodes with concerning features (firm, fixed, >2cm, rapid growth)
Lymphadenopathy associated with fever, weight loss, or night sweats
Assessment of lymph nodes in patients with known cancer for staging
Lymph nodes that persist for >4-6 weeks without resolution
Evaluation of generalized lymphadenopathy for systemic disease
Contraindications
Absolute Contraindications
Relative Contraindications
📋 Equipment Checklist
Check off items as you gather them:
Pre-procedure Preparation
Patient preparation includes obtaining informed consent, reviewing coagulation parameters (platelets >50,000, INR <1.5), and ensuring the patient is not on anticoagulants. The patient should be positioned comfortably to expose the target lymph node. The skin over the lymph node should be cleaned with antiseptic solution. Ultrasound guidance should be arranged for deep-seated or non-palpable lymph nodes.Step-by-Step Procedure
Step 1: Patient Positioning and Site Preparation
Position the patient comfortably to expose the target lymph node. For cervical lymph nodes, position with neck extended. For axillary nodes, abduct the arm. For inguinal nodes, position supine with legs slightly abducted. Clean the skin over the lymph node with antiseptic solution in a circular motion, starting from the center and moving outward. Allow the antiseptic to dry completely.
⚠️ Common Mistakes to Avoid:
- Inadequate positioning leading to difficult access to the lymph node
- Not allowing antiseptic to dry, which can contaminate the specimen
- Inadequate skin preparation increasing infection risk
💡 Pro Tip:
For cervical lymph nodes, ask the patient to turn their head to the opposite side to better expose the target node.
Step 2: Lymph Node Localization
Palpate the lymph node to determine its exact location, size, and consistency. Mark the entry point on the skin. For deep-seated or non-palpable lymph nodes, use ultrasound guidance to visualize the target. Document the lymph node characteristics including size, consistency, and mobility.
⚠️ Common Mistakes to Avoid:
- Not properly localizing the lymph node before aspiration
- Confusing lymph node with other structures (muscle, tendon)
- Inadequate documentation of lymph node characteristics
💡 Pro Tip:
Use ultrasound guidance for deep-seated lymph nodes or those that are difficult to palpate.
Step 3: Needle Insertion and Aspiration
Insert the needle perpendicular to the skin surface and advance it toward the lymph node. Once the needle tip is within the lymph node, apply negative pressure by pulling back the plunger to the 10-15 mL mark. Move the needle back and forth within the lymph node in a fanning motion (5-10 passes) to sample different areas.
⚠️ Common Mistakes to Avoid:
- Inserting the needle too deep and passing through the lymph node
- Insufficient negative pressure causing inadequate cellularity
- Too few passes resulting in poor sampling
💡 Pro Tip:
The "non-aspiration" technique (using capillary action without suction) often yields less bloody samples with adequate cellularity for lymph nodes.
Step 4: Specimen Collection and Processing
Release the negative pressure before withdrawing the needle to prevent aspiration of cells into the syringe. Withdraw the needle swiftly and immediately express the aspirated material onto labeled glass slides. Prepare smears using the "pull-apart" technique. For bloody specimens, use the "squash" technique.
⚠️ Common Mistakes to Avoid:
- Withdrawing needle without releasing pressure, losing specimen in syringe
- Delayed processing causing clotting of the aspirate
- Inadequate labeling leading to specimen mix-ups
💡 Pro Tip:
Prepare both air-dried and alcohol-fixed smears for optimal morphological evaluation and special stains.
Step 5: Multiple Passes and Adequacy Assessment
Perform 2-3 additional passes from different areas of the lymph node to ensure adequate sampling. For large lymph nodes, sample from the periphery and center. Assess adequacy by examining the slides under a microscope if available. Look for adequate representation of lymphoid cells.
⚠️ Common Mistakes to Avoid:
- Insufficient passes causing inadequate sampling
- Not sampling different areas of large lymph nodes
- Not assessing adequacy during the procedure
💡 Pro Tip:
Adequacy criteria for lymph node FNAC require adequate cellularity with representation of lymphoid cells and any abnormal populations.
Step 6: Fixation and Staining
Immediately fix the smears by either immersing in 95% ethanol (wet fixation) or using spray fixative held 25-30 cm from the slide (air-dried for Romanowsky stains). Label slides with patient details, site, and date. Prepare additional slides for special stains if indicated.
⚠️ Common Mistakes to Avoid:
- Delayed fixation causing air-drying artifacts in alcohol-fixed smears
- Spray fixative too close causing cell distortion
- Inadequate labeling leading to specimen mix-ups
💡 Pro Tip:
Prepare two sets of slides: alcohol-fixed for Papanicolaou stain and air-dried for May-Grünwald-Giemsa stain.
Step 7: Post-procedure Care and Documentation
Apply firm pressure to the puncture site for 5-10 minutes using sterile gauze. Check for adequate hemostasis before applying a sterile dressing. Document the procedure including the number of passes, needle gauge used, and gross appearance of aspirate. Provide post-procedure instructions to the patient.
⚠️ Common Mistakes to Avoid:
- Insufficient pressure application leading to hematoma formation
- Inadequate documentation of the procedure
- Not providing clear post-procedure instructions
💡 Pro Tip:
Patients should be observed for at least 15 minutes post-procedure to monitor for complications.
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Post-procedure Care
Post-procedure care involves applying pressure to the puncture site for 5-10 minutes to prevent hematoma formation. Patients should be observed for 15-30 minutes for any immediate complications. Instructions include keeping the site clean and dry for 24 hours, watching for signs of infection or excessive bleeding, and returning for results discussion. Most patients can resume normal activities immediately.Complications & Management
| Complication | Incidence | Signs | Management | Prevention |
|---|---|---|---|---|
| Hematoma | 1-3% | Swelling, pain, discoloration at puncture site | Apply firm pressure for 10-15 minutes, ice pack, observation | Adequate pressure post-procedure, correct coagulation parameters |
| Vasovagal reaction | 0.5-1% | Dizziness, sweating, bradycardia, hypotension | Trendelenburg position, monitor vitals, IV fluids if severe | Perform procedure with patient lying down, calm environment |
| Infection | <0.1% | Erythema, warmth, purulent discharge after 24-48 hours | Antibiotics based on culture, local wound care | Strict aseptic technique, avoid aspirating through infected skin |
| Needle tract seeding | <0.01% | Nodules along needle tract (weeks to months later) | Surgical excision of tract if occurs | Minimize number of passes, avoid FNAC in certain tumors |
| Inadequate sampling | 5-15% | Insufficient cellularity for diagnosis | Repeat FNAC after 3-6 months | Proper technique, adequate number of passes, ultrasound guidance |
Clinical Pearls
The "non-aspiration" technique (using capillary action without suction) often yields less bloody samples with adequate cellularity for lymph nodes.
Always use ultrasound guidance for deep-seated lymph nodes or those that are difficult to palpate to improve adequacy rates.
For large lymph nodes, sample from both the periphery and center to ensure adequate representation of different areas.
Rapid on-site evaluation (ROSE) by a cytopathologist significantly improves adequacy rates and reduces need for repeat procedures.
Document the number of passes, needle gauge used, and gross appearance of aspirate in your procedure note.
The quality of smear preparation is as important as the aspiration technique - poor smears from good aspirates lead to non-diagnostic results.
Be aware of the different cytological patterns in reactive, inflammatory, and neoplastic lymphadenopathy for accurate diagnosis.