What is the best course of action for a 22-year-old female patient with a 2.7 x 1.6 cm inguinal lymph node (lymph node) with mild heterogeneous cortex and preserved fatty hilum (hilum) with hypervascularity, no history of cancer, and a new lymph node behind her ear that is small, soft, movable, but becoming firm and growing, without any reactive symptoms?

Immediate Fine-Needle Aspiration of the Inguinal Node is Required

This 22-year-old patient with a 2.7 cm inguinal lymph node showing concerning features (heterogeneous cortex, hypervascularity) and a new rapidly growing postauricular node requires immediate fine-needle aspiration (FNA) of the inguinal node, followed by excisional biopsy if FNA is negative, to exclude lymphoma or other malignancy. 1, 2

Rationale for Urgent Tissue Diagnosis

The combination of findings is highly concerning and cannot be observed:

• Size threshold exceeded: At 2.7 cm, this node is above the typical reactive threshold and warrants tissue diagnosis 1, 2
• Worrisome imaging features: Heterogeneous cortex with hypervascularity suggests pathologic rather than reactive adenopathy, even with preserved fatty hilum 1
• Progressive disease: The appearance of a second node (postauricular) that is rapidly enlarging and becoming firm within 2 days strongly suggests systemic pathology rather than localized reactive process 3
• Age and absence of reactive triggers: At 22 years old with no infectious symptoms or clear reactive cause, malignancy (particularly lymphoma) must be excluded 1, 3

Diagnostic Algorithm

Step 1: Immediate FNA of Inguinal Node

• FNA is the initial diagnostic step for nodes <4 cm with sensitivity of 91.7% and specificity of 98.2% for malignancy 1
• Target the inguinal node first as it is larger and has been present longer 1, 2
• Send specimen for flow cytometry in addition to cytology given concern for lymphoma in this age group 1

Step 2: If FNA is Negative

• Proceed directly to excisional biopsy rather than surveillance, given the concerning features and progressive nature with new node development 2
• Do not wait 3-4 weeks for observation as typically recommended for less concerning presentations 2

Step 3: Concurrent Imaging

• Obtain CT chest/abdomen/pelvis with IV contrast to assess for additional adenopathy, particularly mediastinal, retroperitoneal, or deeper pelvic nodes 1, 2
• This imaging is indicated given the bilateral distribution (inguinal + postauricular) suggesting possible systemic disease 3

Key Differential Diagnoses to Consider

Primary Concerns (in order of likelihood):

1. Lymphoma (most likely given age, bilateral distribution, rapid progression, firm consistency)

   • Hodgkin or non-Hodgkin lymphoma commonly presents with peripheral adenopathy in young adults 1
   • The rapid firmness and growth pattern of the postauricular node is characteristic 3

2. Metastatic malignancy (less likely without primary lesion but must exclude)

   • Examine genitalia, perineum, lower extremities, and perianal region for occult melanoma, penile lesions, or other primary malignancy 1, 3
   • Inguinal nodes can harbor metastases from lower extremity melanoma, gynecologic malignancy, or rarely lung cancer 1, 4

3. Infectious causes (least likely given lack of reactive symptoms)

   • Lymphogranuloma venereum typically presents with tender unilateral inguinal adenopathy 3
   • This patient's nodes are not described as tender, and the bilateral distribution makes LGV unlikely 3

Critical Pitfalls to Avoid

• Do not observe these nodes: The combination of size, imaging features, and progressive disease with new node development mandates tissue diagnosis 1, 2
• Do not rely on imaging alone: Preserved fatty hilum does not exclude malignancy when other concerning features are present 1
• Do not assume reactive adenopathy: The absence of infectious symptoms, young age, and rapid progression make reactive adenopathy unlikely 3, 2
• Do not delay if FNA is non-diagnostic: Proceed immediately to excisional biopsy rather than repeat FNA 2

Timeline for Action

• FNA should be performed within 48-72 hours given the rapid progression of the postauricular node 1
• Excisional biopsy should follow within 1 week if FNA is negative or non-diagnostic 2
• Imaging should be obtained before or concurrent with biopsy to guide staging if malignancy is confirmed 1, 2

If Malignancy is Confirmed

• Lymphoma: Immediate referral to hematology-oncology for staging and treatment 1
• Metastatic disease: Management depends on primary malignancy identified; for penile cancer, immediate inguinal lymph node dissection would be indicated 1, 3

The preserved fatty hilum is reassuring but does not override the concerning constellation of findings in this young patient with progressive bilateral adenopathy.