AbstractChronic myelogenous leukemia is a myeloproliferative neoplasm characterized by the BCR‐ABL1 fusion gene and the development of the Philadelphia chromosome, which leads to an increase in granulocytes and bone marrow myeloid precursors in the blood, it can lead to many possible complications depending on the disease stage at the time of diagnosis. The Morel‐Lavallée lesion (MLL) is a closed traumatic soft‐tissue degloving injury, that results from the separation of the hypodermis from the underlying fascia, with resultant hemo‐lymphatic fluid collection between the tissue layers. We report a case of a 48‐year‐old male patient, with no chronic illnesses, who presented with 2 weeks history of posterior chest wall pain and swelling. Initial investigation showed a white blood cell count of 364.4 × 10³/μl. Bone marrow pathology report findings were consistent with chronic myeloid leukemia (CML), and the BCR‐ABL test came positive. CT chest with contrast showed a large chest wall lesion, suggestive of a Morel‐Lavallee lesion. Ultrasound‐guided aspiration of the lesion yielded 20 mm of fluid from the thick hematoma. Histopathology of the fluid showed Necrotic debris with mixed inflammation. Patient's condition improved, and he was discharged on Dasatinib with follow‐up in hematology and surgery clinics.