A 5-year-old child with sickle cell anemia (HbSS) develops a sudden onset of fever (38.9°C), pallor, and splenomegaly (spleen acutely increased from baseline). Hb drops from 9 g/dL to 4.5 g/dL within 24 hours. Reticulocyte count is 0.2%. The MOST likely diagnosis is:

• A Acute splenic sequestration crisis
• B Transient aplastic crisis (TAC) due to Parvovirus B19 ✓
• C Hyperhemolytic crisis
• D Acute vaso-occlusive crisis with sequestration

Explanation

Transient aplastic crisis (TAC) in sickle cell disease is caused by Parvovirus B19, which infects and destroys erythroid precursors in the bone marrow. It presents with severe anemia and characteristic reticulocytopenia (reticulocyte count <1%, often near 0%) because the marrow cannot compensate for the normal shortened RBC lifespan in SCD. Without reticulocytosis, the hemoglobin drops precipitously. Acute splenic sequestration causes massive splenomegaly with reticulocytosis as the marrow responds to peripheral trapping. Hyperhemolytic crisis also shows elevated reticulocytes. TAC is managed with red cell transfusion and usually resolves spontaneously in 7–10 days.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.