Histology · Year 1 · from Histology
Case 2: Sickle Cell Disease with Vaso-Occlusive Crisis
Clinical Image
Source: Wikimedia Commons - Sickle Cell Blood Smear - CC BY-SA 3.0
Case Presentation
A 22-year-old African American man with known sickle cell disease presents to the emergency department with severe pain in his back, chest, and bilateral thighs. The pain began suddenly 6 hours ago after he became dehydrated during a basketball game. His vital signs show temperature 38.2C, HR 110, BP 135/85, and SpO2 93% on room air. Physical examination reveals diffuse tenderness over the affected areas without focal findings. Laboratory studies show hemoglobin 7.5 g/dL (his baseline is 8.5), reticulocyte count 12% (elevated, indicating increased RBC production), LDH 450 U/L (elevated, indicating hemolysis), and total bilirubin 3.2 mg/dL (elevated indirect bilirubin from hemolysis). Peripheral blood smear reveals numerous sickled erythrocytes (elongated cells with pointed ends), target cells, and Howell-Jolly bodies (nuclear remnants indicating functional asplenia from repeated splenic infarctions). He is treated with IV fluids, oxygen, and opioid analgesia for vaso-occlusive crisis.
Key Learning Points
- Sickle cell disease results from a mutation in the beta-globin gene producing hemoglobin S (HbS)
- Under low oxygen conditions, HbS polymerizes, causing RBCs to assume rigid, sickle shapes
- Sickled cells are inflexible and cause vaso-occlusion (blocking small vessels), leading to tissue ischemia and pain
- Howell-Jolly bodies on smear indicate functional asplenia from repeated splenic infarcts (auto-splenectomy)
- The disease demonstrates how abnormal hemoglobin structure directly affects RBC morphology and function