Journal of clinical pathology
-
Non-small cell lung carcinoma harbouring epidermal growth factor receptor (EGFR) mutation, usually progress after an initial response to tyrosine-kinase inhibitors (TKI). Liquid biopsy enables with a simple blood draw the accurate detection of EGFR p. T790M mutation, the most common resistance mechanism, avoiding the more invasive tissue re-biopsy. ⋯ At disease progression, the patient developed a morphological transition to squamous cell carcinoma in association to the arising of a PIK3CA p. E542K mutant subclone. This case illustrates that, even in the "liquid biopsy" era, cytology can have still a role by providing an overall assessment of both morphology and genetic TKI resistance mechanisms.