Case Report of CML With Primary Blast Crisis and Marrow Fibrosis
Posted: Tuesday, August 20, 2019
A notable case, of BCR-ABL1– and CBFB-MYH11–positive chronic myeloid leukemia (CML) presenting with primary blast crisis and marrow fibrosis, which ultimately responded to ponatinib, was described by the treatment team in a Letter to the Editor of Annals of Hematology. CBFB-MYH11, the authors noted, is a genomic abnormality in acute myeloid leukemia (AML) that predicts a favorable prognosis. Bone marrow fibrosis leading to dry tap aspiration, often associated with blast crisis, has previously been reported in patients with CML, which is characterized by the presence of the BCR-ABL1 fusion gene.
Severe pneumonia and respiratory failure were the cause of hospital admission for the previously healthy 69-year-old woman, wrote corresponding author Kensuke Kojima, MD, PhD, of Saga University in Japan, and colleagues. Among other test results indicating CML, including an enlarged spleen, her white blood cell count was 234 × 109/L. “Repeated bone marrow aspirations were dry tap,” they noted. “A biopsy specimen showed hypercellular marrow with approximately 30% blasts and grade 2 fibrosis.”
After the patient received induction chemotherapy with cytarabine and daunorubicin, the circulating blast percentage dropped to 1%, the authors reported. However, the percentages of BCR-ABL1–positive cells remained unchanged, and bone marrow aspirations remained dry taps. “The biopsy specimen showed expansion of myeloid progenitor cells at various stages of maturation with approximately 2% blasts and a high myeloid-to-erythroid ratio of 10:1,” added Dr. Kojima and co-investigators. After the patient began taking ponatinib, a hematologic response occurred within 1 month.
Differentiating BCR-ABL1–positive AML from CML with primary blast crisis is challenging, according to the authors. “We applied the recently proposed algorithm for the initial differential diagnosis, which supported the diagnosis of CML [with primary blast crisis],” the team revealed.
Also deserving of investigation is whether the BCR-ABL1 inhibitor ponatinib “can mitigate marrow fibrosis while maintaining remission,” wrote Dr. Kojima and colleagues. “Some BCR-ABL1 tyrosine kinase inhibitors reduce bone marrow fibrosis in CML.”
Disclosure: The study authors reported no conflicts of interest.