Differential Diagnosis

The patient presents with fever, shortness of breath, splenomegaly, anemia (HB-2.8), leukopenia (WBC-3500), and thrombocytopenia (PLT-1Lakh). The laboratory investigations help narrow down the differential diagnoses. Here's the categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Infectious Mononucleosis due to CMV: The patient's symptoms (fever, shortness of breath, splenomegaly) along with the laboratory findings (low HB, WBC, and PLT) and a CMV titre of 1.43 (above the upper limit of 1.1) suggest a recent CMV infection. CMV can cause a mononucleosis syndrome similar to EBV but often with more severe systemic symptoms and cytopenias.

• Other Likely Diagnoses

  • Tuberculosis: Although the Widal test is negative (which is more relevant for typhoid), TB can present with fever, shortness of breath, splenomegaly, and cytopenias due to bone marrow involvement. The absence of a positive CRP or other specific tests does not rule out TB, especially in endemic areas.
  • Brucellosis: This zoonotic infection can cause fever, splenomegaly, and cytopenias. The negative Widal and other tests do not specifically rule out brucellosis, which requires specific serologic tests for diagnosis.
  • Malaria: Although not directly indicated by the provided tests, malaria can cause fever, splenomegaly, anemia, and thrombocytopenia. The diagnosis would require specific malaria tests (e.g., smear, rapid diagnostic tests).

• Do Not Miss Diagnoses

  • Hematological Malignancies (e.g., Leukemia, Lymphoma): These conditions can present with cytopenias, splenomegaly, and systemic symptoms like fever and shortness of breath. A bone marrow biopsy might be necessary for diagnosis.
  • Sickle Cell Disease with Sepsis: Although the hemoglobin level is low, sickle cell disease can cause splenomegaly early in life and sepsis can lead to multi-organ dysfunction. The diagnosis would require hemoglobin electrophoresis.
  • Systemic Lupus Erythematosus (SLE): SLE can present with fever, cytopenias, and splenomegaly. Specific autoantibody tests (e.g., ANA) would be needed for diagnosis.

• Rare Diagnoses

  • Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can present with systemic symptoms, splenomegaly, and cytopenias. Diagnosis requires lymph node or tissue biopsy.
  • Aplastic Anemia: A rare condition characterized by bone marrow failure, which could explain the cytopenias. However, it typically does not cause splenomegaly.
  • Histiocytosis: Rare diseases like Langerhans cell histiocytosis can cause systemic symptoms, splenomegaly, and cytopenias. Diagnosis requires biopsy of affected tissues.