A case report: Concurrent chronic myelomonocytic leukemia and T-cell large granular lymphocytic leukemia-type clonal...

Chronic myelomonocytic leukemia (CMML) is a subtype of myelodysplastic/myeloproliferative neoplasm. Although several studies have reported concurrent myelodysplastic syndrome (MDS) and T-cell large granular lymphocytic leukemia (T-LGL), coexistence of CMML and T-LGL has not been characterized. We describe here a unique case of CMML plus an underlying T-LGL-type clonal proliferation in a patient with a long standing history of severe anemia and recent pancytopenia.

Multiparametric immunophenotyping by flow cytometry was conducted using fresh peripheral blood collected in EDTA. In addition, morphologic evaluation of the peripheral blood smear and T-cell gene rearrangement studies by polymerase chain reaction (PCR) were performed.

Flow cytometric analysis revealed abnormal monocytosis with multiple aberrancies including expression of cross-lineage markers CD2 and CD56, plus reduced expression of multiple antigens. In addition, abnormal CD8+ T-cells were identified, demonstrating dim expression of CD5 and dim to complete loss of CD7. In correlation with clinical history and morphologic review, a diagnosis of CMML plus underlying abnormal CD8+ T-cell lymphoproliferation was made. The clonality of these abnormal T-cells was confirmed by T-cell gene rearrangement studies.

We have identified a unique case of CMML in association with subclinical T-LGL, neither of which, alone, could fully explain the clinicopathologic features identified. Our findings suggest that the coexistence of these two entities may not be coincidental, and it is likely that they may share a common pathogenic pathway related to immune-dysregulation.