A 35 year old woman has had bruising and petechiae for a week. She has also had recent menorrhagia but is otherwise well. Blood: Hgb 11.1, WBC 6.3, Plt 14. What is the single most likely dx?

The key is D. ITP. [As the patient is otherwise well acute leukemia, HIV and SLE is unlikely. Normal wbc count excludes aplastic anemia. So likely diagnosis is ITP. Isolated thrombocytopenia with bruising and petichiae and menorrhagia are strong indicators of ITP. Idiopathic thrombocytopenic purpura, is a type of thrombocytopenic purpura defined as an isolated low platelet count with a normal bone marrow in the absence of other causes of low platelets. Two distinct clinical syndromes manifest as an acute condition in children and a chronic condition in adults. The acute form often follows an infection and spontaneously resolves within two months. Chronic immune thrombocytopenia persists longer than six months with a specific cause being unknown.  ITP is an autoimmune disease with antibodies detectable against several platelet surface structures and the immune system destroys these antibody bearing platelets].