Based on these findings, are additional studies required to make the diagnosis?

Based on the CBC and smear morphology, the patient has an isolated thrombocytopenia, which is

almost certainly the cause of the petechial lesions noted on examination. The history of NHL is important; recurrent disease involving the bone marrow may interfere with platelet production. NHL is also associated with autoimmune thrombocytopenia. The absence of splenomegaly and any evidence of organ damage (TTP) make increased platelet sequestration or organ-based consumption unlikely. To evaluate platelet production, a bone marrow aspirate and biopsy are performed, revealing a normocellular marrow with no evidence of lymphomatous infiltration, but a clear increase in the number of megakaryocytes and the percentage of hyper lobulated megakaryocytes. This finding supports the diagnosis of a destructive thrombocytopenia, most likely an immune thrombocytopenia. A reticulated platelet count of 42% (normal 7%- 1 5%) is further evidence of a platelet destruction defect with a major compensatory increase in production.