Histology · Year 1 · from Histology
Case 3: Acute Myeloid Leukemia
Clinical Image
Source: Wikipedia - Acute Myeloid Leukemia - CC BY-SA 3.0
Case Presentation
A 58-year-old man presents with a two-week history of fatigue, easy bruising, and recurrent nosebleeds. He also reports fevers and night sweats. Physical examination reveals scattered petechiae and ecchymoses, gingival hypertrophy, and mild hepatosplenomegaly. Complete blood count shows: WBC 45,000/mcL with 70% blasts, hemoglobin 7.8 g/dL, and platelets 22,000/mcL. Peripheral blood smear reveals numerous large immature cells (blasts) with high nuclear-to-cytoplasmic ratio, fine chromatin, prominent nucleoli, and some cells containing Auer rods (pink rod-shaped cytoplasmic inclusions pathognomonic for AML). Bone marrow biopsy confirms >90% cellularity with sheets of myeloblasts replacing normal hematopoietic elements. Flow cytometry shows CD34+, CD33+, and CD13+ blasts. He is diagnosed with acute myeloid leukemia and admitted for induction chemotherapy.
Key Learning Points
- Acute leukemias are characterized by accumulation of immature cells (blasts) that fail to mature
- AML originates from the myeloid lineage in bone marrow, crowding out normal hematopoiesis
- Pancytopenia results: anemia (fatigue), thrombocytopenia (bleeding), and functional neutropenia (infections despite high WBC)
- Auer rods are crystallized azurophilic granule contents and are pathognomonic for AML
- Understanding normal hematopoiesis helps explain how leukemic blast accumulation causes the clinical syndrome
Summary: Blood Cell Disorders
These cases illustrate how understanding normal blood cell structure and hematopoiesis informs clinical diagnosis:
| Disorder | Cell Type Affected | Blood Smear Finding | Clinical Manifestation |
|---|---|---|---|
| Iron Deficiency Anemia | RBCs | Microcytic, hypochromic cells, pencil cells | Fatigue, pallor, dyspnea |
| Sickle Cell Disease | RBCs (hemoglobin) | Sickled cells, target cells, Howell-Jolly bodies | Vaso-occlusive pain crises, hemolysis |
| Acute Myeloid Leukemia | Myeloid blasts | Numerous blasts, Auer rods | Pancytopenia (anemia, bleeding, infection) |
The peripheral blood smear remains a critical diagnostic tool, directly visualizing the morphological abnormalities that correlate with disease pathophysiology.