Diagnosis of pulmonary infiltration by acute monocytic leukemia via routine cytological examination of bronchoalveolar lavage fluid: A case report

This article reports a case of pulmonary infiltration by acute monocytic leukemia and discusses the significant role of routine cytological examination of bronchoalveolar lavage fluid (BALF) in the diagnosis of this condition. The patient presented with persistent cough and fever and was ultimately diagnosed with acute monocytic leukemia, accompanied by multiple patchy high-density opacities in both lungs. Leukemic cells were detected through routine cytological examination of BALF samples, leading to a definitive diagnosis of pulmonary leukemic infiltration. The article also reviews relevant literature, discusses the clinical features and genetic abnormalities of acute monocytic leukemia, the incidence and diagnostic challenges of extramedullary infiltration (EMI), and emphasizes the value of routine BALF cytology in disease diagnosis. Acute monocytic leukemia with pulmonary leukemic infiltration is easily misdiagnosed due to non-specific clinical and imaging features. Isocitrate dehydrogenase 2 mutation and Wilms tumor 1 positivity may be associated with extramedullary involvement. Routine cytological examination of BALF can rapidly identify leukemic cells and enable early definite diagnosis. This minimally invasive method has high clinical value and should be widely used for the evaluation of pulmonary infiltration in acute monocytic leukemia.