Primary cutaneous anaplastic large-cell lymphoma (C-ALCL) and cutaneous peripheral T-cell lymphoma not otherwise specified (C-PTL-NOS) are cutaneous T-cell lymphomas with distinct clinical behaviors. Whereas C-ALCL has a favorable prognosis with frequent spontaneous disease regression, C-PTL-NOS runs a more aggressive course. The molecular pathogenesis of these cutaneous T-cell lymphoma types has not yet been studied in detail. In this issue, van Kester et al. report new imbalances that could contribute to our understanding of the differences between these two lymphoma types.