Dysgerminoma is the most common malignant ovarian
germ cell tumor and shares histological and immunophenotypical features with its testicular counterpart,
seminoma. Chromosome 12p abnormalities are genetic hallmarks of testicular
seminomas. Little is known about these genetic changes in
dysgerminoma. We performed dual color fluorescence in situ hybridization (FISH) analyses with a centromeric alpha-satellite probe for chromosome 12 and a subtelomeric probe for 12p on
paraffin-embedded tissue sections from 21
dysgerminomas and two
gonadoblastomas. Chromosome 12p abnormalities were detected in 81% of
dysgerminomas. In all, 57% of cases had only
isochromosome 12p and 5% had only 12p overrepresentation. In all, 19% had both isochrome 12p and 12p overrepresentation.
Gonadoblastomas were negative for
isochromosome 12p or 12p overrepresentation. Chromosome 12p abnormalities are common in
dysgerminoma of the ovary. FISH analyses for chromosome 12p abnormalities may be a useful diagnostic adjunct for confirming the diagnosis of
dysgerminoma and for distinguishing it from nongerm cell
malignancies that enter into the differential diagnosis.