Can we proceed with excision biopsy (surgical removal of a tissue sample for examination) instead of Fine Needle Aspiration Cytology (FNAC)?

Excision Biopsy vs. FNAC: When to Choose Each Approach

Core needle biopsy (CNB) is preferred over both excision biopsy and fine needle aspiration cytology (FNAC) for initial tissue diagnosis of suspicious lesions, with excision biopsy reserved for specific indications when CNB is inadequate or shows concerning features.

Diagnostic Approach to Tissue Sampling

First-Line Approach

• Core Needle Biopsy (CNB) is the preferred initial diagnostic method for most suspicious lesions 1, 2
  • Provides adequate tissue architecture for definitive diagnosis
  • High sensitivity (97-99%) and specificity
  • Allows assessment of histological features and molecular markers
  • Less invasive than excisional biopsy

When to Consider FNAC

• FNAC may be appropriate as an initial approach in specific scenarios:
  • Evaluation of clinically suspicious lymph nodes 1
  • When rapid preliminary diagnosis is needed
  • As a screening tool in resource-limited settings 3
  • For cystic lesions

When to Proceed with Excision Biopsy

Excision biopsy should be performed in the following scenarios:

1. After CNB shows concerning histology:

   • Atypical hyperplasia
   • Lobular carcinoma in situ (LCIS)
   • Indeterminate lesions
   • Benign findings discordant with imaging 1, 2

2. Specific histologies requiring additional tissue:

   • Mucin-producing lesions
   • Potential phyllodes tumor
   • Papillary lesions
   • Radial scars 1, 2

3. When CNB or FNAC is non-diagnostic or inadequate 1

   • Particularly when clinical suspicion remains high

4. For B3 (indeterminate) lesions on core biopsy

   • Studies show approximately 34% of B3 lesions are malignant on excision 4

Limitations of Each Approach

FNAC Limitations

• Cannot reliably assess tissue architecture
• Higher inadequacy rates (up to 16.6% in some studies) 5
• Lower sensitivity compared to CNB (69% vs 88.3%) 3
• Cannot reliably distinguish in-situ from invasive carcinoma

CNB Limitations

• More invasive than FNAC
• Requires local anesthesia
• May miss small lesions
• Sampling errors possible in large heterogeneous tumors 6

Excision Biopsy Limitations

• Most invasive approach
• Requires surgical setting
• Higher cost and recovery time
• May complicate subsequent definitive surgery if malignancy is found

Special Considerations

For Suspected Fibroadenomas

• After CNB confirms fibroadenoma without concerning features, observation with routine screening is appropriate 2
• Excision should be considered if concerning features are present:
  • Size >2.5 cm
  • Rapid growth
  • Clinical suspicion of phyllodes tumor 2

For Lymph Node Assessment

• FNAC is appropriate for initial assessment of suspicious lymph nodes 1
• If FNAC is negative but clinical suspicion remains high, proceed with core biopsy or excisional biopsy 1

Algorithm for Decision Making

1. Initial assessment: Clinical examination + appropriate imaging
2. First diagnostic step: Core needle biopsy (preferred)
3. Decision point:
   • If CNB is diagnostic and benign without concerning features → observation
   • If CNB shows concerning features or is discordant with imaging → excision biopsy
   • If CNB is inadequate → repeat CNB or proceed to excision biopsy

Conclusion

While FNAC has utility in specific scenarios, CNB offers superior diagnostic accuracy and should be the preferred initial approach for tissue diagnosis. Excision biopsy should be reserved for cases where CNB is inadequate or reveals specific concerning features that require complete removal for definitive diagnosis.