🔬Harlequin cells in AML with inv(16) ✅A 66-year-old man was admitted to the hospital with complaints of fatigue and pancytopenia. His hemoglobin level was 74 g/L, white blood cell count 2.6 × 109 /L, and platelet count 39 × 109 /L. A bone marrow examination was performed to evaluate his pancytopenia. May-Grünwald-Giemsa staining of the bone marrow aspirate showed 6% blasts and dysplastic eosinophils with large purplish-violet granules resembling basophilic granules (arrows). Dysplastic eosinophils with metachromatic granules are often referred to as Harlequin cells, which are commonly observed in acute myeloid leukemia (AML) with inv(16)(p13.1q22) or t(16;16)(p13.1;q22) and chronic myeloid leukemia. ✅Conventional cytogenetic analysis of his excess blasts revealed inversion of chromosome 16. Furthermore, the detection of CBFB-MYH11 fusion transcripts by reverse transcription polymerase chain reaction confirmed the diagnosis of AML with inv(16)(p13.1q22). ✅In the World Health Organization classification, acute leukemias include neoplasms with the following specific recurrent cytogenetic abnormalities, regardless of blast percentage: t(8;21)(q22;q22.1), inv(16)(p13.1q22) or t(16;16)(p13.1;q22), and t(15;17)(q24.1;q21.2). ✅After chemotherapy with cytarabine and anthracyclines, the patient’s pancytopenia and dysplastic eosinophils resolved. He remains in remission 6 months later. ✅Harlequin cells imply a myeloid neoplasm regardless of blast percentage.
Acute Myeloid Leukemia with inv(16) and Harlequin Cells
A clinical case of acute myeloid leukemia with chromosome 16 inversion. Discovery of Harlequin cells in bone marrow aspirate.
