What causes inguinal lymph node enlargement in males?

Causes of Inguinal Lymph Node Enlargement in Males

Inguinal lymph node enlargement in males is most commonly caused by inflammatory/infectious processes (30-50% of palpable nodes), followed by malignancy (particularly penile cancer, testicular cancer, and lower extremity malignancies), with less common causes including sexually transmitted infections and periprosthetic joint infections. 1

Primary Etiologies

Inflammatory and Infectious Causes (Most Common)

• Reactive lymphadenopathy accounts for 30-50% of all palpable inguinal lymph nodes, representing the most frequent cause of inguinal node enlargement 2, 1
• Genital herpes simplex virus (HSV) infections commonly cause inguinal lymphadenopathy, though surgical excision for diagnosis is rarely needed due to characteristic external vesicular lesions 3
• Lower extremity infections, including periprosthetic joint infections following hip or knee arthroplasty, can cause localized inguinal lymphadenopathy with median node size of 26mm in infected cases 4
• Sexually transmitted infections affecting the external genitalia drain to inguinal nodes through the superficial lymphatic system 5

Malignant Causes

• Penile cancer represents a critical malignancy causing inguinal lymphadenopathy, with the inguinal lymph nodes being the most frequent site of metastasis 2

  • The glans, inner preputial layer, and coronal sulcus are the most common primary sites (34.5% glans, 13.2% prepuce, 5.3% shaft) 5
  • Up to 25% of patients with clinically non-palpable lymph nodes harbor micrometastases 2
  • Palpable nodes that develop during follow-up are malignant in nearly 100% of cases 2

• Testicular tumors with inguinal lymph node involvement occur in specific circumstances:

  • Patients with history of undescended testis (17 times greater malignancy risk) 6
  • Following orchiopexy or previous inguinal surgery, which alters normal lymphatic drainage patterns 6
  • In these cases, inguinal nodes must be treated (irradiation for seminoma, dissection for non-seminoma) 6

Diagnostic Approach Based on Clinical Presentation

For Palpable Inguinal Lymph Nodes

• Fine-needle aspiration cytology (FNA) is the standard initial diagnostic approach with 91.7% sensitivity and 98.2% specificity for detecting malignancy 1
• Physical examination must document: palpability, number of masses, unilateral vs bilateral presentation, dimensions, mobility vs fixation, and relationship to surrounding structures 2, 1
• If FNA is negative but clinical suspicion remains high, excisional biopsy is required for definitive diagnosis 2, 1

Size-Based Risk Stratification

• Nodes >19mm have 92% sensitivity and 96% specificity for pathologic conditions (particularly periprosthetic joint infection) 4
• Nodes <4cm with negative FNA warrant excision biopsy as next step 2
• Nodes ≥4cm follow the treatment pathway for bulky disease with consideration for neoadjuvant chemotherapy 2

Anatomical Considerations

• Penile lymphatic drainage is highly variable with potential for crossover at presymphyseal lymphatics, allowing contralateral spread even with unilateral primary lesions 5
• Superficial lymphatics drain prepuce and shaft skin, while deep lymphatics drain the glans and deep penile structures, both converging at the femoral triangle 5
• Sentinel lymph nodes are most commonly located in Dassler's superomedial segment 5

Common Pitfalls to Avoid

• Never perform immediate inguinal lymph node dissection for palpable lymphadenopathy without tissue diagnosis, as 30-50% represent inflammatory rather than metastatic disease 2, 1
• Do not assume unilateral primary disease precludes bilateral nodal involvement due to crossover drainage patterns 2, 5
• Avoid relying solely on imaging (CT/MRI) for non-palpable disease, as sensitivity is limited (CT sensitivity only 36%) 2
• In patients with history of inguinal surgery or undescended testis, recognize altered lymphatic drainage patterns that may involve inguinal nodes 6

Management Algorithm

For inflammatory/reactive lymphadenopathy:

• Address underlying infection or inflammation
• Follow-up with serial clinical examinations to monitor node size and characteristics 1

For malignant lymphadenopathy:

• Proceed with appropriate oncologic management based on primary malignancy
• For penile cancer with positive nodes, immediate inguinal lymph node dissection is indicated 1
• Follow-up according to primary cancer protocols with repeat imaging to assess treatment response 1