Long-term Disease Control After Probable Endobronchial Small-cell Transformation During Osimertinib Therapy for EGFR -mutant Lung Adenocarcinoma.
Nozomu Murayama, Minehiko Inomata, Masahiro Matsumoto et al.
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Case in brief
A patient with EGFR exon 19 deletion-positive lung adenocarcinoma had prolonged disease control with osimertinib for mediastinal lymph node recurrence, then developed a new lesion obstructing the left main bronchus. Rigid bronchoscopic resection relieved the obstruction, with temporary airway stenting. Pathology showed small-cell lung cancer (SCLC); concordant p53 over-expression and loss of Rb expression in the original and new lesions supported probable histologic transformation. After chemoradiotherapy, the stent was removed and osimertinib resumed. Disease control continued for more than four years.
What made this case unusual
The probable transformation presented as a locoregionally confined endobronchial lesion causing critical airway obstruction, rather than the widespread metastatic disease commonly described with SCLC transformation.
Diagnostic / clinical pearl
A new endobronchial lesion during osimertinib therapy warrants tissue assessment: pathology and comparison with the original tumor can identify probable small-cell transformation and guide management.
Why it matters
This case illustrates that an individualized multidisciplinary approach, including airway intervention and subsequent chemoradiotherapy, was followed by prolonged disease control after osimertinib was resumed.