Differential Diagnosis

The patient presents with low-grade fever, elevated liver function tests (LFTs), splenomegaly, and a positive EBV IgG, indicating past infection with Epstein-Barr Virus (EBV), along with a negative HIV test and a negative parasite smear. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Chronic Hepatitis: Given the elevated LFTs and splenomegaly, chronic hepatitis (possibly due to hepatitis B or C, which were not specified but could be considered given the liver involvement) is a strong consideration. The positive EBV IgG suggests a past infection, which could also contribute to or be coincidental with the current presentation.

• Other Likely Diagnoses

  • Autoimmune Hepatitis: This condition can cause elevated LFTs and might be associated with splenomegaly. The presence of autoimmune markers and the clinical presentation would support this diagnosis.
  • Sarcoidosis: Although less common, sarcoidosis can cause hepatosplenomegaly, elevated LFTs, and fever. It's a systemic disease that could fit the patient's symptoms.
  • Lymphoma: Given the positive EBV IgG and splenomegaly, lymphoma (especially if associated with EBV) is a consideration, though it might be less likely without other specific symptoms like significant weight loss or night sweats.

• Do Not Miss Diagnoses

  • Tuberculosis (TB): TB can cause fever, splenomegaly, and elevated LFTs. It's crucial to consider TB due to its potential severity and the need for specific treatment. A negative HIV test reduces but does not eliminate the risk.
  • Visceral Leishmaniasis: Although the parasite smear is negative, this diagnosis could be considered, especially if the patient has traveled to or lives in an endemic area. It can cause splenomegaly and systemic symptoms.

• Rare Diagnoses

  • Primary Biliary Cholangitis (PBC): A chronic liver disease characterized by progressive destruction of the bile ducts within the liver, leading to cholestasis and, ultimately, liver cirrhosis. It could present with elevated LFTs but is less likely to cause significant splenomegaly.
  • Histiocytosis: Rare diseases like Langerhans cell histiocytosis can cause hepatosplenomegaly and systemic symptoms, including fever and elevated LFTs. These are less common but should be considered in the differential diagnosis due to their potential severity.