A 34-year-old man with no history of pulmonary disease was diagnosed with CML in September 2019 and was treated with 100 mg of dasatinib for 13 months. Although the dose of dasatinib was reduced to 80 mg because of cytopenia, he achieved an early molecular response at 3 months and maintained a major molecular response.
He visited the emergency department in October 2020 with complaints of CTCAE grade 1 fever and grade 2 headache persisting for 1 week. On examination, he was normotensive but showed fever and tachycardia of 38.3 C and 103 beats per minute, respectively. His respiratory rate was 19 breaths per minute, and oxygen saturation was 96% on room air. Physical examination results, including chest auscultation, were unremarkable. The WBC count was 4.05 x 103/microl, with 59.1% of segmented neutrophils. Except for elevations in grade 1 liver enzymes (aspartate transferase, 53 IU/L; alanine transferase, 51 IU/L) and mild elevation in CRP (1.52 mg/dl; reference range, 0-0.5 mg/dl), there were no significant abnormalities in other laboratory parameters. Chest radiography performed 1 week later showed no abnormalities. However, the fever persisted despite prescribing antipyretics; therefore, a chest CT scan was performed on the 11th day of fever. Chest CT findings revealed ill-defined GGO and consolidation, especially in the left lower lung field (shown in Figure 1(c)). Bronchoalveolar lavage (BAL) fluid analysis showed a lymphocyte-dominant pattern with no evidence of infection, including pneumocystis pneumonia (PCP), cytomegalovirus (CMV), respiratory virus, tuberculosis, or fungus. Echocardiography performed to exclude cardiac problems did not reveal any significant abnormal findings. Because of a suspected diagnosis of dasatinib-associated interstitial pneumonitis, dasatinib was discontinued. The fever resolved 3 days after the discontinuation of dasatinib, and TKI therapy was resumed 16 days after the discontinuation of the TKI, changing to imatinib. Follow-up chest CT performed after 3 months showed a decreased extent of the previously noted GGO (shown in Figure 1(d)). With regular outpatient department visits, the patient maintained molecular response 4.0, without significant toxicity to imatinib.