What is the procedure to get a Fine Needle Aspiration Cytology (FNAC) for a Wharton tumor?

FNAC Procedure for Wharton's Duct Tumor (Submandibular Gland)

For a suspected Wharton's duct tumor (submandibular gland mass), perform ultrasound-guided fine-needle aspiration cytology (FNAC) as the initial diagnostic procedure rather than proceeding directly to open biopsy. 1

Pre-Procedure Preparation

• Confirm the mass location and characteristics through physical examination focusing on the submandibular triangle, assessing for size, consistency (firm vs. fluctuant), mobility, fixation to surrounding structures, and associated lymphadenopathy 1
• Obtain ultrasound imaging first to characterize the lesion (solid vs. cystic components, vascularity, relationship to surrounding structures) and identify the safest needle trajectory 1
• Review any available CT or MRI to assess depth, relationship to major vessels, and presence of additional masses that might alter the sampling approach 1

FNAC Technique Selection

Use ultrasound guidance for the procedure rather than palpation-guided technique, as this improves accuracy and allows real-time visualization of needle placement 1

Needle Selection

• Begin with 22-25 gauge needle for initial passes, as smaller needles (25G) have shown diagnostic accuracy of 95.5% for salivary gland lesions 1
• Consider core needle biopsy (18-20 gauge) if initial FNAC is nondiagnostic, as core biopsy provides tissue architecture and eliminates need for repeat procedures in many cases 1, 2

Sampling Technique

• Perform multiple passes (4-6 passes minimum) using the "fanning technique" to sample different areas of the mass, as this significantly improves diagnostic yield over single-site sampling 1
• Do NOT use suction on initial passes for solid salivary gland masses, as suction increases specimen bloodiness without improving diagnostic yield 1
• If initial aspirate is scant, then apply suction on subsequent passes 1
• Remove the stylet after the first pass for all subsequent passes, as stylet use increases specimen bloodiness without improving diagnostic accuracy 1

Critical Procedural Considerations

Avoid traversing the primary tumor mass when sampling suspicious lymph nodes, as this can cause tumor seeding and affect staging accuracy 1

Place a marker clip if performing core biopsy to identify the lesion location for surgical planning, particularly if the lesion might be entirely removed during sampling 1

Specimen Handling

• Arrange for onsite cytopathology evaluation if available, as this increases diagnostic sensitivity from 78.2% to 96.2% and reduces inadequate samples from 12.6% to 1% 1, 3
• Prepare material for ancillary testing including cell block preparation, immunohistochemistry, and molecular studies, particularly for indeterminate lesions 1, 3
• Express aspirates onto slides using the stylet for controlled specimen preparation 1

Management Based on FNAC Results

If FNAC Shows Warthin Tumor (Most Common Benign Salivary Tumor)

• FNAC has 95% accuracy for Warthin tumor diagnosis when combined with clinical findings and Tc-99m scintigraphy 4, 5
• Conservative observation is acceptable for elderly patients or those unwilling/unable to undergo surgery, as malignant transformation risk is extremely low during follow-up (0% in studies with mean 55-month follow-up) 4, 5
• Surgical excision remains an option for symptomatic patients or those preferring definitive treatment 4, 5

If FNAC Shows High-Grade Malignancy

• FNAC has 94.6% sensitivity and 99.2% specificity for high-grade salivary malignancy, making it highly reliable for surgical planning 6
• Proceed immediately to additional imaging (contrast-enhanced CT/MRI of neck and chest) to assess extent and nodal involvement 6
• Plan for frozen section biopsy during surgery of both tumor margins and suspicious lymph nodes 6
• Extend surgical planning to include neck dissection if indicated by imaging, as high-grade FNAC results change surgical extent in 59% of cases 6

If FNAC is Negative or Indeterminate

A negative FNAC never excludes malignancy when clinical suspicion remains high 1, 3

• If clinical suspicion persists and lymphocytes were seen on FNAC, perform core needle biopsy or proceed to open/excisional biopsy 1
• If FNAC is technically inadequate (insufficient cells, excessive blood), repeat ultrasound-guided FNAC with fanning technique and without suction 1, 3
• If repeat FNAC remains nondiagnostic in a suspicious mass, proceed directly to surgical excision rather than continued surveillance 1

Common Pitfalls to Avoid

• Never rely on FNA alone without imaging guidance for submandibular masses, as blind palpation-guided FNA has significantly lower accuracy 1
• Do not perform open biopsy before attempting FNAC, as this increases complications, costs, and can compromise subsequent imaging interpretation 1
• Avoid sampling only the center of large masses, as necrotic centers yield nondiagnostic material; always use peripheral/fanning sampling 1
• Do not dismiss a benign FNAC result if clinical examination suggests malignancy (rock-hard consistency, fixation, rapid growth, facial nerve involvement), as false-negative rates exist 1, 3, 6