MKSAP Quiz: Petechial rash of the lower limbs
A 29-year-old woman is evaluated for a petechial rash of the lower extremities of 3 weeks' duration. The patient reports no bleeding problems except for recent, occasional bleeding from her gums after brushing her teeth. Medical history is otherwise unremarkable, and she takes no medications.
Physical examination reveals petechiae limited mainly to both lower extremities, with a few similar spots noted on her forearms and abdomen. The remainder of the examination is normal.
MKSAP image (c) American College of Physicians Medical Knowledge Self-Assessment Program
Hemoglobin: 12.5 g/dL (125 g/L)
Leukocyte count: 8500/µL (8.5 × 109/L)
Platelet count: 14,000/µL (14 × 109/L)
Reticulocyte count: 2.0% of erythrocytes
Activated partial thromboplastin time: 26 s
Liver chemistry studies: Normal
Creatinine: 0.8 mg/dL (61.0 µmol/L)
Antinuclear antibody assay: Negative
HIV antibody: Negative
A peripheral blood smear is shown.
Which of the following is the most appropriate next step in management?
Answer and Critique
The correct answer is B: Initiate corticosteroids. This question can be found in MKSAP 15 in the Hematology and Oncology section, item 13.
This healthy young woman has petechiae caused by her very low platelet count with a subacute onset. Although most of her remaining laboratory studies are normal, her peripheral blood smear showing few, but large, platelets supports the presence of a young population of platelets, consistent with increased turnover. These findings are suggestive of immune thrombocytopenic purpura (ITP), and a bone marrow examination is not essential. Instead, a presumptive diagnosis of ITP should be established, and the patient should receive high-dose corticosteroids. Corticosteroids are generally indicated in patients with ITP who have symptomatic bleeding and platelet counts below 50,000/µL (50 × 109/L) or in those with severe thrombocytopenia and platelet counts below 15,000/µL (15 × 109/L).
Platelet transfusions would not be indicated in this patient unless serious, life-threatening bleeding was present. A bone marrow biopsy is not necessary in this setting given the absence of any other signs of a bone marrow stem cell disorder, such as leukopenia or the presence of nucleated erythrocytes, and early myeloid forms suggest a myelophthisic process as occurring in neoplastic and metastatic disease, lymphoma, granulomatous disease, and infections of the bone marrow. Observation alone would be inappropriate in this patient considering her very low platelet count and the risk for bleeding. Splenectomy is not indicated as first-line therapy for ITP but may be considered when other less-invasive therapies have failed.
- Corticosteroids are the first-line treatment for patients with immune thrombocytopenic purpura.
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