In a 25-year-old woman with no comorbidities who has had a low‑grade fever for one month, with initially elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT) now reduced, mildly elevated alkaline phosphatase, low‑normal white blood cell count, negative hepatitis panel, Widal test and dengue serology, and abdominal ultrasound showing peri‑portal and peri‑hepatic lymph nodes up to 18 mm, what are the differential diagnoses and how should the case be further evaluated?

Differential Diagnoses and Diagnostic Approach

In this 25-year-old woman with prolonged low-grade fever, improving transaminitis, periportal lymphadenopathy, and leukopenia, the most critical differentials to pursue are tuberculosis (particularly abdominal TB), Epstein-Barr virus (EBV) infection, cytomegalovirus (CMV) infection, and autoimmune hepatitis, with tuberculosis being the most concerning given the lymphadenopathy pattern and persistent fever despite improving liver enzymes.

Key Differential Diagnoses

High Priority (Must Rule Out)

1. Tuberculosis (Abdominal/Hepatic)

• The periportal and peri-hepatic lymph nodes up to 18mm are highly suggestive
• Prolonged low-grade fever for 1 month is classic
• Leukopenia (WBC 3-4,000) can occur with TB
• Hepatic involvement causes mild-moderate transaminitis with elevated ALP
• Critical to diagnose early given mortality implications

2. EBV/CMV Infection

• Both cause prolonged fever, hepatitis, and lymphadenopathy
• Transaminitis typically peaks at 8-9 days but can persist 1
• Leukopenia with atypical lymphocytes is characteristic
• For marked ALT elevations, viral hepatitis including CMV should be considered 2

3. Autoimmune Hepatitis

• Young women are the classic demographic
• Can present with prolonged fever and hepatitis
• Periportal inflammation may cause lymphadenopathy on imaging
• Requires specific serological testing 2, 3

Moderate Priority

4. Lymphoproliferative Disorders

• Lymphoma can present with fever, lymphadenopathy, and mild hepatitis
• Leukopenia may indicate bone marrow involvement
• The 18mm lymph nodes warrant consideration

5. Drug-Induced Liver Injury

• Must obtain detailed medication history including over-the-counter, herbal, and traditional medicines 2, 3
• Improving transaminases may reflect drug discontinuation

Algorithmic Diagnostic Approach

Immediate Next Steps (Within 48 Hours)

Laboratory Investigations:

1. Infectious workup:

   • EBV serology (VCA IgM, EBNA)
   • CMV IgM and PCR
   • Tuberculin skin test (TST) or Interferon-Gamma Release Assay (IGRA)
   • Blood cultures for mycobacteria (BACTEC)
   • HIV testing

2. Autoimmune/Inflammatory markers:

   • Antinuclear antibody (ANA)
   • Anti-smooth muscle antibody (ASMA)
   • Anti-liver kidney microsomal antibody (anti-LKM)
   • Immunoglobulin G levels (elevated in autoimmune hepatitis) 2, 3
   • Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)

3. Complete liver aetiology screen (core panel): 2

   • Ferritin and transferrin saturation (hemochromatosis)
   • Ceruloplasmin and 24-hour urinary copper (Wilson disease - critical in young patients)
   • Alpha-1 antitrypsin level
   • Repeat hepatitis panel if initial testing was done during acute phase

4. Hematologic evaluation:

   • Peripheral blood smear (atypical lymphocytes, abnormal cells)
   • Lactate dehydrogenase (LDH) - elevated in lymphoproliferative disorders

Imaging Studies

1. Contrast-Enhanced CT Abdomen (Preferred over repeat ultrasound):

• Better characterization of lymph nodes (necrotic centers suggest TB)
• Evaluate for hepatosplenomegaly
• Assess for other abdominal pathology
• Look for ascites or peritoneal involvement

2. Chest X-ray:

• Screen for pulmonary tuberculosis
• Evaluate for mediastinal lymphadenopathy

If Initial Workup Non-Diagnostic

1. Lymph node biopsy/Fine needle aspiration:

• This becomes critical if TB workup is negative but clinical suspicion remains high
• Histopathology, culture, and PCR for mycobacteria
• Flow cytometry if lymphoma suspected

2. Liver biopsy: 2, 3

• Consider when serologic testing and imaging fail to establish diagnosis
• Can identify granulomas (TB, sarcoidosis), autoimmune hepatitis, or infiltrative processes
• May be needed to stage disease severity

3. Bone marrow examination:

• If persistent unexplained leukopenia
• Evaluate for infiltrative processes or hemophagocytic syndrome

Critical Clinical Pitfalls to Avoid

1. Do not assume improving transaminases mean resolving disease - The persistent fever with lymphadenopathy suggests ongoing systemic process despite hepatic recovery

2. Do not delay TB evaluation - Abdominal TB is notoriously difficult to diagnose and can cause significant morbidity if treatment is delayed. The lymphadenopathy pattern is highly suggestive 2

3. Do not overlook Wilson disease - At 25 years old, this is a critical age for presentation. Missing this diagnosis has severe mortality implications 1, 3

4. Do not repeat the same basic tests - As per guidelines, 84% of abnormal liver tests remain abnormal at 1 month, so focus on determining etiology rather than monitoring 2

5. Leukopenia is a key finding - This narrows differentials significantly and suggests viral infection, TB, autoimmune disease, or bone marrow involvement rather than typical bacterial infections

Pattern Recognition

The clinical pattern of:

• Prolonged fever (1 month) + improving hepatocellular injury + periportal lymphadenopathy + leukopenia most closely matches either:
  • Tuberculosis (most concerning for mortality)
  • EBV/CMV infection (most common in this age group)
  • Autoimmune hepatitis (demographic fit)

The hepatocellular pattern of injury (AST/ALT elevated more than ALP) with mild ALP elevation suggests either infectious or autoimmune etiology rather than primary cholestatic disease 1, 3.