Tehran University of Medical Sciences International Journal of Hematology-Oncology and Stem Cell Research 2008-2207 18 4 2024 10 12 401 403 Shanza Adnan Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan Saba Farrukh Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan Arsalan Ahmed Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan Muhammad Shariq Shaikh Aga Khan University 2023 03 03 2023 06 19 Hairy cell leukemia (HCL) is a rare B-cell neoplasm that constitutes around 2 percent of all lymphoid leukemias and occurs more frequently in elderly males. The usual triad of HCL includes pancytopenia, splenomegaly, and hairy cells in the bone marrow. This is a case of an atypical presentation of biclonal HCL diagnosed on flow cytometry; the existence of biclonal HCL is extremely rare with very few case reports. Pure biclonal HCL should be regarded as an extraordinary finding among the so-called composite lymphomas.   https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/view/1993 https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/download/1993/1056