Organizing pneumonia resembling disease progression in a non-small-cell lung cancer patient receiving ceritinib A case report

Rationale: Echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK), a distinct molecular entity, is highly sensitive to ALK tyrosine kinase inhibitors (TKIs) such as crizotinib or ceritinib. Interstitial lung disease is a rare (1.2%) pulmonary toxicity that can result from ALK TKIs, however, organizing pneumonia has not been reported to date. Patient concerns: A 45-year-old Korean female with ALK-rearranged metastatic lung adenocarcinoma underwent ceritinib treatment and exhibited a partial response, until she developed organizing pneumonia resembling disease progression. Diagnoses: Multiple rebiopsies confirmed the involvement of organizing pneumonia in the pathology. Interventions: Ceritinib was stopped and the patient was treated with intravenous antibiotics followed by oral antibiotics for two weeks. Outcomes: After recovering from organizing pneumonia, ceritinib was successfully rechallenged and the patient attained a complete response. Lessons: When a new mass-like lesion develops in the lungs of responding patients, benign lung conditions, including organizing pneumonia should be considered in differential diagnoses.