Lymphocytosis with Smudge Cells Is Not Equivalent to Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) often presents with lymphocytosis and smudge cells (SCs) on routine peripheral blood (PB) tests. In some cases, these findings are assumed to be sufficient to diagnose CLL. We present a 54-year-old male who was referred for further management of progressing CLL. At the initial presentation, he looked unwell and had diffuse lymphadenopathy and splenomegaly. Blood work showed normocytic anemia (hemoglobin 72 g/L), thrombocytopenia (platelet count 74 × 10⁹/L), leukocytosis (white blood cell count 135.5 × 10⁹/L) including lymphocytosis (130.1 × 10⁹/L), and the presence of SCs on a PB smear. Additional workup including flow cytometry (FC), bone marrow biopsy, and lymph node biopsy led to a diagnosis of leukemic stage of advanced-stage mantle cell lymphoma. Although lymphocytosis with SCs is more frequently and in higher quantities seen in CLL they are not pathognomonic and can be present in a variety of lymphoproliferative disorders. Additional diagnostic examination of cell morphology and FC to assess clonality and determine the immunotype of lymphocytes are required to establish an accurate diagnosis and determine appropriate further management of the specific disease type.