Which of the following is an indication for bone marrow biopsy in a patient with suspected idiopathic thrombocytopenic purpura?

Which of the following is an indication for bone marrow biopsy in a patient with suspected idiopathic thrombocytopenic purpura?
A. Use of corticosteroid therapy for treatment
B. Use of intravenous immunoglobulin for treatment
C. Platelet count less than 50,000

D. Thrombocytopenia persisting for more than 1 month
E. Thrombocytopenia with normal hemoglobin and white blood cell counts

Answer : A. Use of corticosteroid therapy for treatment

Discussion: The most common cause for thrombocytopenia in children is acute idiopathic thrombocytopenic purpura (ITP), a viral-related autoimmune destruction of platelets. The classic presentation is the occurrence of petechiae following a viral infection. Patients are typically asymptomatic and have a normal physical examination but are found to have an isolated decreased platelet count on laboratory evaluation. In most patients, the platelet count returns to normal in less than 6 months. However, up to 20% of patients will have persistent thrombocytopenia, which is then termed chronic ITP. In patients with acute ITP who have no signs of bleeding and platelet counts above 20,000, no therapy may be necessary. In these patients, platelet counts should be monitored until they return to normal. When the platelet count is less than 20,000, or there is bleeding or excessive bruising, then therapy is generally indicated. Intravenous immunoglobulin and/or corticosteroids are used to raise platelet counts. Since malignancy is also a cause for thrombocytopenia, bone marrow examination should be performed prior to use of corticosteroids, which may mask an underlying malignancy. Intravenous immunoglobulin does not have any effects on malignant disease and thus may be used without need for a bone marrow biopsy before treatment. Immunoglobulin therapy will raise platelet counts within 48 to 72 hours and can assist in confirming the diagnosis. If during the clinical examination the patient is found to have lymphadenopathy, splenomegaly, or symptoms suggestive of underlying disease, thena bone marrow evaluation is warranted. Finally, persistent thrombocytopenia, other abnormal cell lines (i.e., WBC and RBC), and uncertainty regarding the diagnosis also should prompt consideration of performing a bone marrow biopsy.