Cytogenetic analysis of three oropharyngeal malignant melanomas in dogs

Three cases of histologically confirmed oropharyngeal malignant melanomas i n dogs are presented including clinical examinations and cytogenetic analys is. Case one showed a hyperdiploid karyotype. Case two, a recurrent tumour, had a highly hypodiploid karyotype with supernumerary meta- and submetacen tric chromosomes in all metaphases analysed. In the third case, a clonal fu sion of chromosome 1 and 25 was observed. Comparing these results with anot her case of canine cutaneous melanoma as well as with human malignant melan omas reported in the literature, these tumours obviously often show cytogen etic aberrations like aneuploidy and centric fusions. (C) 1999 Harcourt Pub lishers Limited.