Recent efforts have been made to isolate molecular targets that could explain different outcome between histological subtypes of lymphomas and to understand the molecular mechanisms underlying oncogenic events. Using the SSH technique, we compared the transcriptome of 2 cases of ALK+ and ALK- anaplastic large cell lymphoma (ALCL) and of 2 cases of classical Hodgkin's lymphoma (cHL) with opposite behavior. Regarding ALCL, we showed that ALK-positive tumors overexpressed genes involved in different signaling pathways such as activation or signaling of T-cells, regulation of apoptosis, phospholipase Cgamma and phosphatidyl inositol-3 Kinase. In addition, the characterization of a specific molecular signature may be of clinical relevance since ALK+ tumors generally have a better prognosis than ALK- ones. Similar problems of differential prognosis is observed in cases of cHL, which in addition, may be morphologically and immunologically indistinguishable. Therefore, we applied the same SSH technique to 2 cHL samples from patients with favorable and poor outcome, respectively. Forty-four cDNAs were significantly overexpressed in the poor outcome case. In addition to the defender against death cell 1 (DAD1) gene, overexpressed clones corresponded mostly to expressed sequence tags (ESTs). Interestingly, the present study identifies new genes which may be involved in the pathogenesis and/or clinical outcome of cHL and deserve further investigations.