This patient presents with isolated thrombocytopenia with no other clear causes for this abnormality; therefore, the most likely diagnosis is immune thrombocytopenic purpura (ITP). Given his symptoms and low platelet count prednisone is the best initial step in management.
ITP is an autoimmune condition that can coexist with other autoimmune disorders or stand alone. The diagnosis is based on the presence of an isolated low platelet count, absence of other etiologies for low platelet count (especially medications, acute infection/systemic illness, chronic viral infection), and absence of platelet clumping (pseudothrombocytopenia) on peripheral blood smear. For patients without active bleeding and a platelet count greater than 30,000/uL, expectant management is appropriate.
Figure A shows the peripheral blood smear of a patient with ITP. Notably, it shows isolated thrombocytopenia without RBC pathologies and the absence of platelet clumping. Peripheral blood smear is part of the workup for thrombocytopenia. Illustration A shows a small cluster of platelets that have aggregated together in one part of the slide. When an automated blood count machine interprets this slide, it will generate a falsely low platelet count. This is why pseudothrombocytopenia must be ruled out in patients with an isolated low platelet count.
Answer 1: Observation would be incorrect in the setting of symptomatic bleeding and a low platelet count.
Answer 3: Rituximab has shown promise in the treatment of ITP, but is generally reserved as a second-line treatment.
Answer 4: IVIG is generally used to rapidly increase a patient's platelet count, such as prior to a procedure or in the case of severe thrombocytopenia. It can also be used as a 'bridge' between first- and second-line therapies.
Answer 5: Platelet transfusion is typically withheld unless major bleeding (ICH, severe GI bleeding) is present.