An unusual recurrence of adenosquamous carcinoma of the lung

Adenosquamous carcinoma of the lung is an uncommon histological variant of non-small cell lung carcinoma (NSCLC) associated with a poorer prognosis than either adenocarcinoma or squamous cell carcinoma (SCC) histological subtypes. Most adenosquamous carcinomas of the lung present with advanced disease, often with the central nervous system as a common site of metastasis. We present a case of a patient with recurrent adenosquamous carcinoma who presents with multiple cerebral metastases, with two metastatic sites composed of separate distinct histological subtypes, one adenocarcinoma and one SCC. Interestingly, both metastatic deposits were also found to harbor an L858R epithelial growth factor receptor (EGFR) point mutation in exon 21. Upon progression after craniotomy and whole brain radiotherapy, the patient achieved a radiological response with the EGFR inhibitor, erlotinib.