Clonal Analysis of Adenosquamous Carcinoma of the Lung

Adenosquamous carcinoma of the lung is a subset of pulmonary carcinomas, and comprises less than 4% of lung carcinomas. Its histogenesis remains unclear. The clonality of adenosquamous carcinoma from four female patients was analyzed to determine whether the clonality between the squamous cell and adenocarcinomatous components coincides. Each lesion was precisely microdissected from methanol‐fixed sections. Adjacent normal lung tissue was collected as a normal control. DNA was extracted for clonal analysis based on an X‐chromosome‐linked polymorphic marker, the human androgen receptor gene (HUMARA). HUMARA was found to be amplified with or without previous digestion by the methylation‐sensitive restriction endonuclease HpaII. All four cases were informative. Squamous cell and adenocarcinomatous components showed identical monoclonal patterns in all four patients. In one case, only the squamous cell carcinomatous component showed loss of heterozygosity of the HUMARA locus. The results suggest that the squamous cell and adenocarcinomatous components originate from the same cell.