Diagnostic Approach and Management of Unilateral Inguinal Lymphadenopathy

Initial Evaluation and Diagnostic Steps

The American College of Surgeons and the National Comprehensive Cancer Network recommend fine-needle aspiration (FNA) as the initial diagnostic step for unilateral inguinal lymphadenopathy, particularly for nodes <4 cm, with a sensitivity of 91.7% and specificity of 98.2% for malignancy 1, 2
A focused examination should document node characteristics, including size, number, mobility, consistency, and relationship to surrounding structures, to guide further management 3, 4, 5
The National Comprehensive Cancer Network suggests that laterality, associated findings, and primary lesion search should be assessed, including examination of the genitalia, perineum, lower extremities, and perianal region for potential primary malignancy 3, 4, 5

The National Comprehensive Cancer Network recommends CT abdomen and pelvis with IV contrast as the preferred imaging modality for nodes that are borderline enlarged or difficult to assess clinically, with concern for deeper pelvic or retroperitoneal involvement, or suspected metastatic disease 1, 5
For nodes ≥4 cm, imaging should be obtained before biopsy to assess extent, location, and relationship to surrounding structures, and FNA should be performed regardless of mobility status 6, 1

The National Comprehensive Cancer Network suggests that if FNA is positive for malignancy, immediate oncologic management should be initiated based on the primary malignancy identified, and for penile cancer, immediate inguinal lymph node dissection (ILND) should be performed 2, 6, 7
If FNA is negative, confirmation with excisional biopsy or careful surveillance every 3 months should be considered, and re-biopsy should be performed if nodes enlarge or new systemic symptoms develop 1, 2
The Centers for Disease Control and Prevention recommend treating lymphogranuloma venereum (LGV) with doxycycline 100 mg orally twice daily for 21 days, and considering LGV in sexually active patients with tender unilateral inguinal lymphadenopathy 8, 9

The American College of Radiology suggests that tenderness does not exclude malignancy, and size is the strongest predictor of pathology in lymph nodes 10

The National Comprehensive Cancer Network recommends considering metastatic disease, such as penile cancer, melanoma, anal cancer, lower extremity sarcoma, or gynecologic malignancy, in the differential diagnosis of inguinal lymphadenopathy 11
The American Society of Hematology suggests considering lymphoma, particularly if B symptoms develop, in the differential diagnosis of inguinal lymphadenopathy 12
The National Comprehensive Cancer Network recommends immediate inguinal lymph node dissection (ILND) for penile cancer, and considering neoadjuvant chemotherapy before surgical resection for nodes ≥4 cm 11, 13