To whom should I refer a patient with an abnormally enlarged inguinal lymph node, potentially with a history of cancer or risk factors for malignancy, for further evaluation and biopsy?

Referral for Inguinal Lymph Node Evaluation and Biopsy

Refer patients with abnormally enlarged inguinal lymph nodes to interventional radiology for ultrasound-guided fine-needle aspiration cytology (FNAC) as the first-line diagnostic approach. 1

Primary Referral Pathway

For Initial Tissue Diagnosis

• Interventional radiology is the primary specialty for performing ultrasound-guided FNAC of inguinal lymph nodes, as this is the preferred diagnostic approach recommended by multiple guidelines 1
• Surgeons with specific training in FNAC techniques can also perform this procedure 1
• FNAC should be performed for all palpable inguinal nodes <4 cm to distinguish between inflammatory (30-50% of cases) and metastatic disease 2, 3

When FNAC is Negative but Suspicion Remains High

• Refer to surgical oncology for excisional biopsy if FNAC is negative but clinical suspicion persists 2, 3
• A negative FNAC must be confirmed with either excisional biopsy or careful surveillance, as false-negatives occur 2

Specialty-Specific Referral Considerations

For Suspected Penile Cancer

• Urologic oncology should be consulted early if penile lesions are present, as they will ultimately manage both the primary tumor and coordinate lymph node dissection if metastases are confirmed 2
• For high-risk primary lesions (T1G3 or worse), consider omitting FNAC and proceeding directly to inguinal lymph node dissection to avoid treatment delays 2

For Suspected Vulvar Cancer

• Gynecologic oncology is the appropriate referral for vulvar malignancies with inguinal lymphadenopathy 2
• Surgical staging with inguinofemoral lymphadenectomy or sentinel lymph node biopsy is performed by gynecologic oncologists 2

For Dynamic Sentinel Node Biopsy (DSNB)

• Surgical oncology or specialized centers with expertise in lymphoscintigraphy and blue dye localization should perform DSNB when available 2, 1
• DSNB is indicated for intermediate or high-risk disease with clinically non-palpable nodes (cN0) 2
• The technique has a 97% identification rate and 7% false-negative rate when performed by experienced teams 2

Clinical Decision Algorithm

Step 1: Initial Assessment

• Document node size, mobility, unilateral vs bilateral presentation, and relationship to surrounding structures 3
• Obtain ultrasound if nodes are non-palpable but patient has risk factors 1

Step 2: Tissue Diagnosis

• Nodes <4 cm and palpable: Refer to interventional radiology for ultrasound-guided FNAC 2, 1
• Nodes ≥4 cm or fixed: Refer to interventional radiology for FNAC, then surgical oncology for definitive management 2
• Non-palpable nodes in high-risk patients: Refer for DSNB if available, or ultrasound-guided FNAC if DSNB unavailable 2, 1

Step 3: If FNAC is Negative

• Repeat biopsy or proceed to excisional biopsy via surgical oncology referral 2, 3
• Consider surveillance only if patient is reliable and clinical suspicion is low 3

Step 4: If FNAC is Positive

• Immediate referral to surgical oncology (urologic or gynecologic depending on primary site) for inguinal lymph node dissection 2, 3
• Imaging with CT or MRI to assess for pelvic lymph node involvement 2

Critical Pitfalls to Avoid

• Do not assume all palpable inguinal nodes are malignant: 30-50% are inflammatory at initial presentation 2, 3
• Do not proceed directly to surgical excision without FNAC: This leads to unnecessary morbidity in inflammatory cases 3
• Do not delay lymphadenectomy in high-risk primary tumors: For T1G3 or worse penile lesions, proceed directly to surgical oncology rather than waiting for FNAC results 2
• Do not rely solely on CT or MRI for non-palpable nodes: These have low sensitivity (36% for CT) and should not replace tissue diagnosis 2
• Do not accept a single negative FNAC in clinically suspicious nodes: Confirm with excisional biopsy 2, 3

Special Circumstances

When DSNB is Not Available

• Ultrasound-guided FNAC becomes the primary diagnostic modality 2, 1
• Consider risk stratification using nomograms to guide surveillance vs prophylactic lymph node dissection 4

For Obese Patients or Prior Inguinal Surgery

• Physical examination is unreliable; imaging-guided approaches are essential 2
• Lower threshold for referral to interventional radiology for ultrasound-guided procedures 1