Acute basophilic leukemia presenting with abnormal liver function tests and the absence of blast cells in the peripheral blood

Approach to Acute Myeloid Leukemia with Increased Eosinophils and Basophils

There is remarkable morphologic and genetic heterogeneity in acute myeloid leukemia (AML). In a small percentage of cases of AML, increased eosinophils and/or basophils are present in the bone marrow and sometimes in the peripheral blood. This is often a puzzling diagnostic situation but also an important finding that requires special investigation. Unique chromosomal rearrangements have been correlated with an increased number of eosinophils and basophils in AML. The identification of the underlying genetic lesion that promotes eosinophilia and basophilia can dramatically change both the prognosis and the treatment of the patient. Thus, clinicians must be vigilant in searching for the cause of eosinophilia and basophilia in patients with AML, since the different causes may lead to different treatments and survival outcomes. In this article, we examine the significance of increased eosinophils and/or basophils in the context of AML, provide guidance that simplifies the differential diagnosis, and give prognostic and therapeutic information about specific subtypes of AML associated with eosinophilia and/or basophilia. Evidence supporting personalized (molecularly targeted) therapy for these patients is also presented.

Uncommon phenotypes of acute myelogenous leukemia: basophilic, mast cell, eosinophilic, and myeloid dendritic cell subtypes: a review

The potential of the transformed (leukemic) multipotential hematopoietic cell to differentiate and mature along any myeloid lineage forms the basis for the phenotypic classification of acute and chronic myelogenous leukemia. Although most cases of leukemia can be classified phenotypically by the dominant lineage expressed, the genotype within each phenotype is heterogeneous. Thus, covert genetic factors, cryptic mutations, and/or polymorphisms may interact with the seminal transforming genetic mutations to determine phenotype. The phenotype usually is expressed sufficiently to determine the lineage that is dominant in the leukemic clone by light microscopic examination, by cytochemistry of blood and marrow cells, and by immunophenotyping. The basis for the frequency of the AML phenotypes is unclear, although there is a rough concordance with the frequency of marrow precursor cells of different lineages. The least common AML phenotypes are a reflection of the least common blood or marrow cell lineages: acute basophilic, acute mast cell, acute eosinophilic, and acute myeloid dendritic cell leukemia. We discuss the features of these uncommon phenotypes and review the criteria used for their diagnosis.

Acute basophilic leukemia: case report

The term "basophilic leukemia" has been in use for 75 years. However, consistent diagnostic criteria are lacking. This is due to the rarity of the disease and to the routine unavailability of special tests that are often required to confirm a diagnosis. We report an unusual case of acute basophilic leukemia in a child who was referred to our Center, arriving with partially treated acute lymphoblastic leukemia. Basophilic differentiation on light microscopy was evident from the coarse basophilic granules in blasts, a progressive maturation of blasts toward basophils, and toluidine positivity on cytochemistry. Blasts showed a myeloid immunophenotype (CD13+, CD33+, CD117+) with a characteristic dual positivity for CD34 and CD25, highly suggestive of basophilic nature of the blasts. Conventional cytogenetic studies revealed translocation t(8;21)(q22;q22). A diagnosis of acute basophilic leukemia with t(8;21) was made. Review of pre-therapy slides showed features consistent with AML-M2 with basophilia. There were no basophilic blasts. With these features, a diagnosis of acute basophilic leukemia secondary to AML-M2 was made. In our patient, basophilic leukemia appears to have evolved from selective clonal proliferation of "basophil-committed blasts" during the course of the disease in a case of AML-M2 with basophilia.

Acute basophilic leukemia lacking basophil-specific antigens: the importance of cytokine receptor expression in differential diagnosis

De novo acute basophilic leukemia (ABL) is a rare form of myeloid leukemia. The low prevalence of ABL makes it difficult to define its clinical characteristics and to establish an effective therapeutic protocol. We present here a case of de novo ABL in a 64-year-old Japanese man. The diagnosis of ABL depended on the following: (1) metachromasia with toluidine blue stain, (2) intracytoplasmic theta granules identified by electron microscopy, and (3) findings obtained from extensive immunophenotypic analysis. Although blast cells lacked basophil-specific antigens such as CDw17, CD88, and FcepsilonRI, an expression profile of cytokine receptors including CD116 (GM-CSF receptor), CD117 (c-kit), and CD123 (IL-3 receptor alpha) helped to define the cellular lineage in our case. The patient achieved complete remission with intensive chemotherapy composed of idarubicin and cytosine arabinoside and was disease free during the following 30 months. We propose that immunophenotyping, especially focusing on cytokine receptors, is useful in diagnosing ABL.