What is the recommended treatment for a deep, firm, and mobile groin nodule?

Recommended Treatment for Deep, Firm, Mobile Groin Nodule

Fine-needle aspiration (FNA) is the mandatory first diagnostic step for any palpable groin nodule, as it provides high diagnostic accuracy (91.7% sensitivity, 98.2% specificity) while avoiding unnecessary surgical morbidity. 1, 2

Initial Diagnostic Workup

Before proceeding with FNA, perform a focused clinical examination evaluating:

• Nodule characteristics: Size, mobility versus fixation, unilateral versus bilateral presentation, and relationship to surrounding structures 1, 2
• Primary lesion search: Carefully inspect the penis, vulva, lower extremities, and all skin surfaces for suspicious lesions that could represent primary malignancies 1
• Constitutional symptoms: Assess for fatigue, weight loss, and night sweats suggesting systemic disease 1
• Lymph node basin: Examine for additional palpable nodes in the inguinal and pelvic regions 3

Management Algorithm Based on FNA Results

If FNA is Negative:

• Confirm with excisional biopsy given that 30-50% of palpable inguinal lymphadenopathy is inflammatory rather than malignant 1, 2
• Alternatively, careful surveillance may be considered, but excisional biopsy is preferred for deep, firm nodules to definitively exclude malignancy 1, 4
• Address any underlying infectious or inflammatory causes identified 2, 4

If FNA is Positive for Malignancy:

• Proceed immediately with disease-specific oncologic management based on the primary malignancy identified 2
• For penile cancer: Immediate inguinofemoral lymphadenectomy is warranted 3, 1
• For vulvar cancer: Inguinofemoral lymphadenectomy or sentinel lymph node biopsy depending on primary tumor characteristics 3
• For melanoma: Consider pelvic lymph node dissection given 30-44% risk of pelvic involvement with multiple palpable nodes 1

Imaging Considerations

CT abdomen and pelvis with IV contrast is recommended for comprehensive assessment if:

• The nodule is borderline enlarged or has concerning features 1
• Multiple nodes are present 1
• Malignancy is confirmed on FNA to evaluate extent of disease 3, 1

CT provides evaluation of lymph node size, extent, location, enhancement patterns, and assessment for pelvic/retroperitoneal involvement 1, 2

Critical Differential Diagnoses

The most important malignant etiologies to exclude include:

• Penile squamous cell carcinoma: 20-25% of clinically node-negative patients harbor occult metastases; lymph node status is the strongest predictor of survival 1
• Vulvar cancer: Nodal involvement is the strongest independent predictor of relapse 1
• Melanoma of lower extremity: Can present with inguinal lymphadenopathy 1
• Lymphoma: Should be considered in the differential 2

Benign etiologies include reactive lymphadenopathy from skin/soft tissue infections of the lower extremity or perineum 2

Critical Pitfalls to Avoid

• Do not proceed to immediate surgical excision without FNA, as this leads to unnecessary morbidity and delays diagnosis 1, 2, 4
• Do not assume all palpable lymphadenopathy is malignant, as 30-50% of cases are inflammatory 1, 2, 4
• Do not delay evaluation beyond 4 weeks, as early diagnosis of malignancy significantly improves outcomes 1
• Do not rely solely on a negative FNA without confirmatory excisional biopsy or close surveillance 1, 4

Specialist Referral

Referral to a hematologist-oncologist is appropriate for coordinating diagnostic evaluation, as they can determine whether the nodule represents benign reactive changes or malignancy and coordinate appropriate imaging, biopsy techniques, and immunohistochemical studies 1

Subsequent referrals to urologic oncology, gynecologic oncology, or surgical oncology may be indicated based on the primary malignancy identified 1