Hematology Oncology · Year 2 · from Hematology Oncology
Case 1: Immune Thrombocytopenia (ITP)
Patient Presentation
Demographics: 28-year-old female
Chief Complaint: Easy bruising and petechiae for 2 weeks
History of Present Illness: The patient noticed increasing bruising on her extremities over the past 2 weeks, occurring with minimal or no trauma. She also developed a petechial rash on her lower legs. She reports heavier than usual menstrual periods this cycle. She had a viral upper respiratory infection approximately 3 weeks ago that resolved spontaneously. She denies any fever, weight loss, bone pain, or other systemic symptoms. She takes no regular medications and has no history of bleeding disorders.
Physical Examination:
- Vital signs: BP 118/72, HR 78, RR 14, Temp 36.8C
- General: Well-appearing young woman
- Skin: Multiple ecchymoses on arms and legs; petechial rash on lower extremities
- HEENT: No gingival bleeding, no lymphadenopathy
- Cardiac: Regular rhythm, no murmurs
- Abdomen: Soft, non-tender, no hepatosplenomegaly
- Neurologic: Normal
Workup and Results
Complete Blood Count:
- WBC: 7,200/uL (normal differential)
- Hemoglobin: 12.8 g/dL (normal)
- Platelets: 8,000/uL (severely low)
- MCV: 88 fL (normal)
Peripheral Blood Smear:
- Markedly decreased platelets
- Large platelets (megathrombocytes) visible
- Normal RBC and WBC morphology
- No schistocytes or blasts
Additional Labs:
- PT/INR: 12.5 sec / 1.0 (normal)
- aPTT: 28 sec (normal)
- Fibrinogen: 285 mg/dL (normal)
- LDH: 180 U/L (normal)
- HIV, HCV: Negative
Clinical Image
Peripheral blood smear in immune thrombocytopenia showing markedly reduced platelet count with large platelets (megathrombocytes) indicating increased bone marrow production in response to peripheral destruction.
Diagnosis
Primary Immune Thrombocytopenia (ITP)
Diagnostic criteria:
- Isolated thrombocytopenia (<100,000/uL) with no other cause identified
- Normal or increased platelet size (young platelets)
- Normal RBC and WBC morphology
- Negative secondary workup (HIV, HCV)
- No splenomegaly
- Post-viral trigger common in young adults
Treatment Plan
- First-line therapy:
- Prednisone 1 mg/kg/day for 2-4 weeks with taper
- Or dexamethasone 40 mg daily x 4 days
- Adjunctive measures:
- Avoid aspirin, NSAIDs, and anticoagulants
- Activity restrictions to prevent trauma
- If severe bleeding or refractory:
- IVIG 1 g/kg x 1-2 doses (rapid but temporary effect)
- Anti-D immunoglobulin (if Rh-positive)
- Second-line options if needed:
- Thrombopoietin receptor agonists (romiplostim, eltrombopag)
- Rituximab
- Splenectomy (third-line)
Teaching Points
- ITP is a diagnosis of exclusion - other causes of thrombocytopenia must be ruled out
- Large platelets suggest increased bone marrow production in response to peripheral destruction
- The mechanism involves antiplatelet antibodies (often anti-GPIIb/IIIa) causing splenic destruction
- Primary ITP has no identifiable cause; secondary ITP occurs with underlying conditions
- Treatment is based on platelet count and bleeding symptoms, not just the number
- Many patients with platelets >30,000/uL require no treatment if asymptomatic