A 6-year-old boy with sickle cell disease presents with pallor and fatigue. Hemoglobin has fallen from 8 g/dL to 4 g/dL. Peripheral smear shows no polychromasia and the reticulocyte count is 0.2%. Two weeks ago he had a low-grade fever and a bright red facial rash. What is the most likely cause of this deterioration?

• A Splenic sequestration with circulating nucleated red cells
• B Autoimmune hemolytic anemia with spherocytes
• C Megaloblastic crisis due to folate deficiency
• D Parvovirus B19 induced pure red cell aplasia ✓

Explanation

Parvovirus B19 infects erythroid progenitor cells via the P antigen and temporarily halts red cell production. In chronic hemolysis this causes transient aplastic crisis with profound reticulocytopenia, and the antecedent slapped cheek rash points to recent infection. Splenic sequestration, option A, shows a rapidly enlarging spleen and reticulocytosis rather than reticulocytopenia.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.