A young patient is admitted with petechiae on the oral mucosa and bleeding along the gum margins. Laboratory results show a platelet count of 45,000 per cubic millimeter, prolonged bleeding time, and delayed clot retraction, while red and white blood cell counts remain normal. What is the most likely diagnosis?

Explanation

The patient's symptoms of oral petechiae, gum bleeding, low platelet count, and increased bleeding and clot retraction times, combined with normal red and white blood cell counts, are characteristic of infectious mononucleosis. Other conditions like thrombocytopenic purpura and leukemia typically present with different blood count abnormalities, and hemophilia primarily involves clotting factor deficiencies rather than platelet issues.