What urgent diagnostic work‑up and initial management are recommended for a patient presenting with pancytopenia, inflamed enlarged lymphadenopathy (including pancreatic nodes), and elevated liver enzymes?

Urgent Diagnostic Work-Up and Management

This presentation demands immediate evaluation for hemophagocytic lymphohistiocytosis (HLH) and lymphoma-associated HLH, as 40-70% of adult HLH cases are malignancy-triggered, with lymphoma being the most common culprit 1.

Immediate Diagnostic Priority

The constellation of pancytopenia, inflamed enlarged lymphadenopathy (including pancreatic nodes), and elevated liver enzymes strongly suggests either:

1. Lymphoma-associated HLH (most urgent)
2. Primary lymphoma with systemic involvement
3. Less likely: isolated nutritional deficiency or infection

Critical First-Line Testing

Obtain these labs immediately:

• Ferritin (markedly elevated in HLH, often >10,000 ng/mL)
• Soluble CD25 (sCD25) and calculate sCD25/ferritin ratio (elevated ratio suggests lymphoma-associated HLH) 1
• Triglycerides (elevated in HLH)
• Fibrinogen (decreased in HLH)
• NK cell function and CD107a upregulation (impaired in HLH)
• EBV PCR (quantitative viral load, as EBV is strongly associated with certain lymphoma subtypes and HLH) 1

Imaging:

• PET-CT scan urgently - This is the gold standard for detecting occult lymphoma, which can hide in unusual locations including perisplenic tissue 1, 2
• PET-CT will identify optimal biopsy sites and reveal the full extent of FDG-avid disease 2

Tissue Diagnosis is Mandatory

Obtain tissue biopsy from the most accessible enlarged lymph node:

• The guidelines explicitly state that lymphoma as an HLH trigger "may be difficult to detect" and recommend repetitive tissue sampling if initial biopsies are non-diagnostic 1
• Consult a lymphoma reference pathologist - tumor-infiltrating reactive lymphocytes can mask underlying lymphoma 1
• High-risk lymphoma subtypes associated with HLH include: Hodgkin lymphoma, NK/T-cell lymphoma, angioimmunoblastic T-cell lymphoma, peripheral T-cell lymphoma, and intravascular B-cell lymphoma 1

Common Pitfalls to Avoid

Do not delay treatment waiting for genetic testing results - while genetic analyses for primary HLH genes (PRF1, UNC13D, STX11, etc.) should be sent, pending results must not delay clinical decision to treat HLH 1. Primary HLH is rare in adults (only 7% in U.S. registries) 1.

Do not assume reactive lymphadenopathy - the case report 3 illustrates how peripheral T-cell lymphoma can present exactly like this with "initially presumed reactive" lymphadenopathy, requiring extensive investigations for diagnosis.

Do not stop at negative initial biopsies - if clinical suspicion remains high and splenomegaly is present, splenectomy may be considered to detect lymphomas hiding in the spleen or perisplenic tissue 1.

Initial Management Considerations

If HLH is confirmed (meeting diagnostic criteria):

• HLH-94 protocol components including etoposide are highly effective and have strong consensus support 1
• The protocol includes: dexamethasone, cyclosporine A, intrathecal therapy, and etoposide
• This treatment transformed pediatric HLH from uniformly fatal to >50% long-term survival 1

However, treatment approach depends on underlying trigger:

• If lymphoma-associated HLH is identified, treating the underlying lymphoma is essential
• The heterogeneity of adult HLH prohibits a "one-size-fits-all protocol" 1

Less Likely Differentials (But Rule Out)

While the presentation strongly suggests HLH/lymphoma, briefly exclude:

• Vitamin B12 deficiency - can cause pancytopenia with lymphadenopathy and elevated LFTs 4, but typically shows macrocytosis and hypersegmented neutrophils
• Visceral leishmaniasis - only relevant if endemic area exposure 5
• Autoimmune conditions (SLE with EBV) - can mimic this presentation 6

The key distinguishing feature is the PET-CT findings and tissue diagnosis, which will definitively separate malignancy-driven processes from reversible causes.