Newly diagnosed T-large granular lymphocyte Leukemia presenting with severe neutropenia: a case report.

T-large granular lymphocyte leukemia (T-LGLL) is an uncommon chronic lymphoproliferative syndrome marked by clonal proliferation of cytotoxic (CD8+) T cells. It is usually characterized by cytopenia, particularly neutropenia, and may be associated with autoimmune disease. We report a case of a 56-year-old Moroccan female patient presenting with a 2-month history of dry eye syndrome, asthenia, and severe neutropenia. Initial investigations revealed lymphocytosis, and the peripheral blood smear revealed approximately 13% of large granular lymphocytes. Flow cytometry confirmed T-LGLL with a CD3+, CD8+, CD57+ phenotype. First-line treatment with low-dose methotrexate yielded no improvement after six months. The patient was then successfully treated with oral cyclophosphamide, with normalization of neutrophil and hemoglobin levels, and resolution of sicca symptoms. This case highlights the importance of early diagnosis and tailored immunosuppressive therapy in managing T-LGLL, particularly in patients with severe neutropenia.