Unusual Case of B-Chronic Lymphocytic Leukemia with Coexistence of Precursor T-Acute Lymphoblastic Leukemia Status Post Transplant

Background: Coexistence of Chronic lymphocytic lymphoma (CLL) to Acute lymphoblastic leukemia is extremely rare with only a few reported cases [1-5]. Chronic lymphocytic leukemia is a neoplasm of small monomorphic round to irregularly shaped lymphocytes of B-cell lineage. Adverse prognostic factors in CLL include flow cytometric expression of ZAP-70 and CD38 which are surrogate markers for the mutational status of IVIg. T-cell acute lymphoblastic leukemia (T-ALL) is a neoplasm of lymphoblasts that are of T-cell lineage and are small to medium-sized cells. Case Report: We present a case of a 62-year-old man, diagnosed with B-Chronic Lymphocytic Leukemia who was treated successfully twice. A year following an allogeneic stem cell transplantation (SCT), the CLL returned for a third time along with a secondary diagnosis of T-cell acute lymphoblastic leukemia. Our review of literature explores the potential pathophysiologic mechanisms of the coexistence of these two diagnoses. Conclusion: Chronic lymphocytic leukemia has been known to evolve into various lymphoid transformations, including diffuse large b-cell lymphoma, and prolymphocytic leukemia, however the coexistence and transformation of CLL to T-cell acute lymphoblastic lymphoma is extremely rare. Potential mechanisms of this phenomemon may include a common genetic predisposition, a malignant transformation of a common progenitor cell, immune deregulation, chronic stimulation of T-cells by the B-CLL cells, adverse effects of chemotherapy exposure, increased T-cell resistance to apoptosis, or to the slight occurrence of pure chance. Numerous hypotheses exist, however the precise relation of the two entities coexisting is unknown due to limited research and only a few known cases. Open Journal of Hematology