Clinical Scenario:
A 6-year-old child presents with a 6-week history of intermittent fever, progressive pallor, and painful swelling of the knees and ankles. Examination reveals cervical lymphadenopathy, oral thrush, and a papulovesicular rash over the neck, face, and upper chest. The liver is palpable 5 cm and the spleen 3 cm below the costal margin.
The child has a history of recurrent asthma-like respiratory symptoms for the past 2 years.
Investigations show:
- Hb: 6.8 g/dL
- TLC: 4,500/mm³
- Neutrophils: 31%
- Lymphocytes: 23%
- Eosinophils: 7%
- ESR: 45 mm/hr
- Urine: albumin 2+, numerous RBCs, 4–6 WBCs/HPF
What is the most likely underlying diagnosis?
A. Acute lymphoblastic leukemia
B. HIV infection
C. Hyper-IgE syndrome
D. Systemic juvenile idiopathic arthritis
E. Systemic lupus erythematosus
Correct answer & Explanation:
Correct answer: B
Explanation
The combination of prolonged fever, cervical lymphadenopathy, hepatosplenomegaly, cytopenia, oral candidiasis, papulovesicular skin lesions, arthritis, and renal abnormalities strongly suggests an underlying immunodeficiency, with paediatric HIV infection being the most likely diagnosis.
Oral thrush is particularly important in a 6-year-old because persistent or significant mucosal candidiasis should raise suspicion of an underlying immunodeficiency. The associated cytopenia, hepatosplenomegaly and chronic inflammatory features further support HIV infection.
The arthritis/arthralgia and renal involvement with proteinuria and hematuria can also occur as extra-immune manifestations of HIV infection.
Why the other options are less likely
- A. Acute lymphoblastic leukaemia: Anaemia, lymphadenopathy and hepatosplenomegaly could fit, but oral thrush, papulovesicular rash and the combination of renal and joint manifestations make an underlying immunodeficiency more suggestive. A peripheral smear and bone marrow examination would be important if leukaemia were suspected.
- C. Hyper-IgE syndrome: Recurrent infections, eczema-like skin disease and eosinophilia can occur, but the overall presentation with cytopenia, hepatosplenomegaly and renal involvement is not typical.
- D. Systemic juvenile idiopathic arthritis: Prolonged fever, arthritis and hepatosplenomegaly may occur, but oral candidiasis and the described rash are atypical. The absence of the characteristic quotidian fever pattern also makes it less likely.
- E. Systemic lupus erythematosus: Arthritis, cytopenias, proteinuria/haematuria and lymphadenopathy can strongly suggest SLE. However, oral thrush and the overall immunodeficiency phenotype make HIV an important and more likely unifying diagnosis in this scenario.
Key exam clue
Persistent oral candidiasis + chronic fever + lymphadenopathy/hepatosplenomegaly + cytopenia ± renal/joint involvement = think HIV/immunodeficiency.
