Chronic myelomonocytic leukemia presenting as relapsing thrombotic thrombocytopenic purpura

A 67-year-old woman presented with fever, purpura, and confusion. A preliminary diagnosis of thrombotic thrombocytopenic purpura (TTP) was made on the basis of clinical presentation and lab findings, such as reduced platelet count, increased bilirubin, and so on. She was treated with therapeutic plasma exchange (TPE) and methylprednisolone. During the treatment, peripheral blood monocytosis (monocyte 4 × 10(9)/L) was noticed. The monocytes were CD56 positive. A putative diagnosis of chronic myelomonocytic leukemia (CMML) was proposed. Three months later, the diagnosis of CMML was established on the basis of persistent monocytosis. All other potential causes were considered (e.g., quinine exposure, diarrhea) and excluded. This case highlights the needs to consider hematological malignancy such as CMML in patients with TTP.