Chromosome 9p deletion in squamous metaplasia in cystic lesion of the lung.

A 70-year-old man presented with squamous cell carcinoma of the lung. Examination of the resected specimen showed a tumour and a thickly walled cyst not immediately adjacent to the main tumour. The surface of the cyst was lined by squamous metaplastic epithelium. Microsatellite analysis of microdissected specimens was performed with seven markers from four chromosomal regions. In the squamous cell carcinoma, a non-informative homozygosity at two markers on 3p, loss of heterozygosity (LOH) at D5S346 on 5q, and LOH at D9S146, D9S150, and D9S1748 on 9p were detected. In the metaplastic epithelium of the cyst, LOH was detected at D9S1748 on 9p21. This appears to be the first report providing possible evidence of genetic changes by demonstrating allelic loss on 9p21 in the metaplastic epithelium of a cyst. This allelic loss might be related to an early step in carcinogenesis in lung cysts.