Introduction: The simultaneous or sequential occurrence of hematologic malignancies derived from divergent cellular lineages (myeloid and lymphoid) represents an extremely rare clinical and immunobiological phenomenon. The emergence of small lymphocytic lymphoma / chronic lymphocytic leukemia (SLL/CLL) as a metachronous second primary tumor during maintenance therapy and close surveillance of chronic myeloid leukemia (CML) poses a true challenge for differential pathological diagnosis and targeted therapeutic strategies. Objective: To report the diagnostic process, immunohistochemical characterization, and interdisciplinary clinical management of a patient who developed SLL after achieving a deep molecular response for CML under tyrosine kinase inhibitor (TKI) therapy. Case and Methods: A 47-year-old male with an established diagnosis of chronic phase CML with BCR::ABL1 p210 fusion transcript, treated with dasatinib (100 mg daily), achieved a Major Molecular Response. During his 3-year evolutionary surveillance, he developed left supraclavicular and right cervical lymphadenopathies. Neck ultrasound demonstrated rounded nodes with a loss of the corticomedullary relationship. An excisional biopsy of the right cervical lymph node was performed, revealing infiltration by mature monoclonal B lymphoid cells with a CD20+, CD43+, BCL2+, MUM1+ profile, and a Ki67 index of 15%, confirming SLL. During follow-up, the patient developed a pericardial effusion that required the scheduled temporary suspension of the TKI. Conclusions: Sequential myeloid/lymphoid coexistence requires meticulous differentiation between a clonal evolution of a common pluripotential stem cell versus two biologically independent malignancies. Management must be guided by the stratification of IWCLL criteria, individualizing the need for chemoimmunotherapy versus the continuation of TKI therapy.
Olivares et al. (Fri,) studied this question.
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