Chromosomal imbalances: a hallmark of tumour relapse in primary cutaneous CD30+ T-cell lymphoma.

Primary cutaneous CD30+ large T-cell lymphoma (CD30+ CTCL) is a subset of non-epidermotropic primary cutaneous T-cell lymphoma. Although frequent spontaneous regression may be observed, skin relapses occur frequently. Cytogenetic abnormalities that could play a role in CD30+ CTCL tumour pathogenesis and relapses remain unknown. The identification of recurrent cytogenetic abnormalities is hampered by difficulty in culturing tumours and the lack of CD30+ CTCL serial studies comparing genetic changes both at diagnosis and at relapse. The purpose of this study was to investigate the cytogenetic abnormalities present in a series of 13 CD30+ CTCL samples obtained from nine patients fulfilling both EORTC and WHO diagnostic criteria, by the use of comparative genomic hybridization (CGH). CGH analysis revealed a non-random distribution of genetic imbalances between relapsing and non-relapsing disease. In relapsing disease, chromosomal abnormalities were detected both in the primary tumour and in relapses. The mean number of changes in non-relapsing disease was 0.33 (range 0-1), compared with 6.29 (range 1-16) in relapsing disease. The recurrent chromosomes involved in relapsing disease were chromosomes 6 (86%), 9 (86%), and 18 (43%). While chromosome 9 was mostly affected by gain, chromosomes 6 and 18 mainly contained regions of loss, exclusively on 6q and 18p. The common regions of deletion were 6q21 and 18p11.3. In one patient, we successfully cultured tumour cells from a skin biopsy from a second relapse. The G-banded karyotype was concordant with both CGH and fluorescence in situ hybridization (FISH) results. Although further studies are required to strengthen these data, this CGH analysis demonstrates chromosomal imbalances that may be involved in the pathogenesis of relapsing CD30+ CTCL.