Interphase cytogenetic analysis of 1(q)12 satellite III DNA in melanocyticlesions - Increased aneuploidy with malignant histology

To examine the relationship of chromosome 1 copy number to melanocytic tumo rigenesis, interphase cytogenetic analysis of 1q12 satellite III DNA was pe rformed on the spectrum of melanocytic lesions comprising Clark's tumor pro gression model. Results showed increased copy number in a "step off" patter n between melanoma in-situ and the intraepidermal component of invasive mel anoma rather than a progression between each lesional group. These findings support Clark's concept of independent clonal expansion of a cell populati on giving rise to the vertical growth phase and further demonstrates increa sed chromosome 1 copy number as a late event in melanoma tumor progression.