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Zorluk: KolayPediatric Hematology and Oncology

A 4-year-old boy is brought to the pediatrician's office by his parents after they noticed a red, pinpoint rash on his legs and arms this morning. The patient had a mild upper respiratory tract infection two weeks ago but has completely recovered. He is currently active and well-appearing. His temperature is 37.0°C (98.6°F), blood pressure is 95/60 mmHg, pulse is 90/min, and respirations are 20/min. Physical examination reveals scattered petechiae and purpura over the lower extremities. There is no hepatosplenomegaly, lymphadenopathy, or joint swelling. Laboratory evaluation shows:

Hemoglobin: 12.2 g/dL
Leukocyte count: 7,500/mm³
Platelet count: 15,000/mm³
Prothrombin time: 11 seconds (normal: 11-15 seconds)
Activated partial thromboplastin time: 30 seconds (normal: 25-40 seconds)

Which of the following is the most likely diagnosis?

  1. Immune thrombocytopeniaCevap
  2. B
    Acute lymphoblastic leukemia
  3. C
    Meningococcemia
  4. D
    IgA vasculitis
  5. E
    Von Willebrand disease

Cevap

Immune thrombocytopenia
The correct diagnosis is Immune thrombocytopenia (ITP). ITP is an acquired autoimmune disorder characterized by isolated thrombocytopenia (platelet count < 100,000/mm³). In children, it most commonly presents at ages 2-5 years, typically occurring 1-4 weeks after a viral infection. The patient develops a sudden onset of petechiae, purpura, and mucosal bleeding but remains otherwise asymptomatic and well-appearing. Physical examination is notable for the absence of hepatosplenomegaly or lymphadenopathy, which helps differentiate ITP from malignancies like leukemia. The diagnostic hallmark is isolated thrombocytopenia with a normal white blood cell count, normal hemoglobin level, and normal coagulation profile (PT and aPTT).

Adım Adım Çözüm

1
Analyze the patient's clinical presentation.
A well-appearing 4-year-old child presents with petechiae and purpura following a recent viral upper respiratory infection. He has no hepatosplenomegaly or lymphadenopathy.
Identifying the clinical stability and physical exam findings helps rule out severe systemic illnesses or malignancies.
2
Interpret the laboratory findings.
The patient has isolated thrombocytopenia (platelets 15,000/mm³) with normal hemoglobin, leukocyte count, and coagulation studies (PT and aPTT).
Normal hemoglobin and leukocyte counts point away from bone marrow failure or leukemia. Normal coagulation studies rule out factor deficiencies and DIC.
3
Synthesize findings to determine the diagnosis.
Isolated thrombocytopenia in a well-appearing child after a viral illness is the classic presentation of immune thrombocytopenia.
Antibodies to platelet surface antigens often form after viral infections, leading to platelet destruction in the spleen.

Anahtar Kavram

Immune thrombocytopenia (ITP) in children typically presents with sudden onset of petechiae and purpura in an otherwise healthy, well-appearing child, often following a viral infection. Laboratory testing reveals isolated thrombocytopenia.
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Pediatric Hematology and Oncology

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