Abstract
We present a 63-year-old male patient with acute myeloid leukemia (AML). His hemoglobin level was 10.0 g/dL, white cell count was 16.78 × 103/μL with 94.6% blasts, and platelet count was 91 × 103/μL. The bone marrow had 20% cellularity with 87.0% blasts. Approximately 20% of blasts in the peripheral blood exhibited cup-like nuclear morphology, and many mitochondria were concentrated within the nuclear pocket under electron microscopy. The blasts were negative for myeloperoxidase, but expressed CD13 and CD33. CD34 was positive and HLA-DR was weak. The cells demonstrated normal G-banding cytogenetics, and lacked FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) and nucleophosmin 1 (NPM1) gene mutation. The patient relapsed shortly after a response to initial chemotherapy and died 9 months after presentation. To date, we have encountered a total of 6 cases of cup-like AML in our institution. The ages ranged from 62 to 80 and male to female ratio was 3 to 3. Two had French-American-British M0, one had M1, two had myelomonocytic/monocytic leukemia, and the remaining one had hypoplastic leukemia. Two presented with marked leukocytosis, while the other two had leukopenia. All cases exhibited expression of myeloid antigens, and weak or negative expression of CD34 and/or HLA-DR. All cases carried a normal karyotype, and four had FLT3-ITD or NPM1 mutations, or both. In the nuclear indentation, a condensed collection of mitochondria was observed in all. At present, it remains to be determined whether cup-like nuclear morphology represents a distinctive AML subtype associated with particular clinical features, genetic abnormality, or treatment outcome.
