Imatinib-Associated Interstitial Lung Disease with a Fibrotic NSIP Pattern on Transbronchial Lung Cryobiopsy: A Case Report and Review of the Literature.

Background and Clinical Significance: Interstitial lung disease (ILD) is an uncommon but potentially serious complication of imatinib. Its histopathological characterization has so far relied on surgical biopsy or transbronchial forceps sampling, and no case characterized by transbronchial lung cryobiopsy (TBLC) has been reported. The single previous description of a non-specific interstitial pneumonia (NSIP) pattern with imatinib came from a surgical specimen and was cellular in type, with complete radiological resolution after withdrawal. Case Presentation: A 69-year-old never-smoker began imatinib 400 mg daily for Philadelphia chromosome-positive chronic myeloid leukemia; chest computed tomography performed immediately beforehand was normal. Approximately three months later, she developed dyspnea, dry cough and a cutaneous rash, progressing to acute respiratory failure with forced vital capacity 49% and diffusing capacity 30% of predicted. Avian exposure had ceased one month before symptom onset, and she had never received amiodarone. Although serum precipitins were unavailable, hypersensitivity pneumonitis was considered less likely given the temporal relationship but could not be definitively excluded. TBLC yielded specimens showing fibrotic thickening of the alveolar septa by hyaline collagen deposition with a focal lymphomonocytic infiltrate, corresponding to a fibrotic NSIP pattern. After drug withdrawal and administration of corticosteroids, forced vital capacity rose to 82% of predicted. Multidisciplinary discussion concluded that this was drug-induced ILD, graded probable on the Naranjo scale. Imatinib was subsequently replaced by bosutinib for insufficient molecular response, without pulmonary recurrence. Conclusions: Imatinib-associated ILD may present with an organizing-pneumonia-like radiological pattern followed by a fibrosing pattern, with cryobiopsy performed later demonstrating fibrotic NSIP. Because no tissue was obtained during the acute phase, this sequence remains a hypothesis rather than a demonstrated evolution. Cryobiopsy can be performed safely when surgical biopsy is not appropriate.