What is the appropriate management for a patient presenting with unilateral inguinal lymphadenopathy?

Management of Unilateral Inguinal Lymphadenopathy

Fine-needle aspiration (FNA) is the mandatory first diagnostic step for unilateral inguinal lymphadenopathy, with immediate oncologic management if positive and excisional biopsy confirmation if negative. 1, 2

Initial Clinical Assessment

Document the following node characteristics to guide management:

• Size measurement (critical threshold: <4 cm vs ≥4 cm determines pathway) 3
• Mobility status (mobile vs fixed to surrounding structures) 3
• Number of nodes and laterality (unilateral vs bilateral) 3, 1
• Relationship to skin and deeper structures (Cooper ligament involvement, skin infiltration) 3

Perform a focused examination of potential primary sites including genitalia, perineum, lower extremities, and perianal region to identify occult malignancy. 1, 4

Size-Based Diagnostic Algorithm

For Nodes <4 cm (Unilateral, Mobile)

Proceed directly to FNA with sensitivity of 91.7% and specificity of 98.2% for malignancy. 1, 2 This is the standard initial approach recommended by the National Comprehensive Cancer Network. 3

• If FNA positive: Immediate inguinal lymph node dissection (ILND) for penile cancer or appropriate oncologic management based on primary malignancy identified 3, 4
• If FNA negative: Confirm with excisional biopsy or careful surveillance every 3 months, as 30-50% of palpable inguinal lymphadenopathy is inflammatory rather than malignant 3, 1, 2

Critical pitfall: Do not assume all palpable nodes are malignant—inflammatory lymph node swelling accounts for 30-50% of cases. 3, 4

For Nodes ≥4 cm (Fixed or Mobile)

Obtain CT abdomen/pelvis with IV contrast before biopsy to assess extent, location, and relationship to surrounding structures. 1, 2, 4

Perform FNA regardless of mobility status. 3, 1 For large mobile nodes amenable to resection, proceed with standard or modified ILND if positive. 3

Consider neoadjuvant chemotherapy (paclitaxel, ifosfamide, cisplatin) before surgical resection for bulky disease, as this multimodal approach achieves 50% objective response rates with improved time to progression and overall survival. 3

Management Based on FNA Results

Positive FNA

• Penile cancer: Immediate ILND 3, 1
• Other malignancies: Disease-specific oncologic protocols 4
• Abnormal pelvic lymph nodes on imaging: Systemic chemotherapy or concurrent chemoradiation with consideration of confirmatory biopsy 3

Negative FNA

Do not rely on negative FNA alone—confirm with excisional biopsy, which is the gold standard providing the most tissue for pathologic evaluation. 2, 4 Alternatively, careful surveillance every 3 months is acceptable with re-biopsy if nodes enlarge or new systemic symptoms develop. 1, 2

Infectious Considerations

For sexually active patients with tender unilateral inguinal lymphadenopathy, consider lymphogranuloma venereum (LGV) and treat with doxycycline 100 mg orally twice daily for 21 days. 1 A complete sexual history and genital examination can prevent unnecessary invasive diagnostics. 5

Imaging Indications

CT abdomen/pelvis with IV contrast is preferred when:

• Nodes are borderline enlarged or difficult to assess clinically 1, 2
• Concern exists for deeper pelvic or retroperitoneal involvement 1
• Nodes measure ≥4 cm 1, 4
• Patient is obese or has undergone prior inguinal surgery making physical examination challenging 3

Note: CT and MRI have limited utility for nonpalpable disease, with sensitivity of only 58-60% for detecting metastases in normal-sized nodes. 3, 2

Follow-Up Strategy

For confirmed reactive lymphadenopathy after negative biopsy, perform clinical examination every 3 months with re-biopsy if nodes enlarge or new systemic symptoms develop. 2, 4

Critical pitfall: Do not proceed to immediate surgical excision without FNA, as this leads to unnecessary morbidity and delays diagnosis. 4

Avoid corticosteroids without an appropriate diagnosis, as they can mask the histologic diagnosis of lymphoma or other malignancy. 6, 7