Isochromosomes of both short and long arms of chromosome 12 resulting in an additional copy of chromosome 12 in a case of splenic lymphoma with villous lymphocytes

We report a case of splenic lymphoma with villous lymphocytes showing a karyotype with an isochromosone for both the long arm and the short arm of chromosome 12, i(12)(p10) and i(12)(q10), effectively resulting in trisomy 12. This is, apparently, the first decumented case of an additional copy of chromosome 12 resulting from isochromosone formation in a neoplastic disorder.