Introduction: The assessment of prognosis is a major step in the management of primary cutaneous lymphomas, as it allows to give patients an accurate information and it directs the treatment choice.
Material and methods: We performed a literature review of global prognosis and prognostic factors in primary cutaneous lymphomas. We used survival as the main endpoint, in particular specific survival and relative survival which provide accurate estimates of lymphoma-related deaths. Independent prognostic factors identified by multivariate survival analyses were emphasized.
Results: Overall prognosis of mycosis fungoides has improved during the past decades, possibly because of an increased proportion of cases diagnosed at early stages. Five-year disease-specific or relative survival rates of patients with T1 stage (patch/plaque disease<10 p. 100 of total skin surface), T2 (> 10 p. 100), T3 (tumor stage) and T4 (generalized erythroderma) are 100 p. 100, 67 to 96 p. 100, 51 to 80 p. 100 and 41 p. 100 respectively. Lymphomatoid papulosis and CD30+ primary cutaneous large T-cell lymphomas have an excellent prognosis, with 5-year survival rates of 100 p. 100 and 96 p. 100 respectively. CD30-negative primary cutaneous large T-cell lymphomas have an aggressive clinical behavior (5-year disease-specific or relative survival: 15 to 21 p. 100). Among primary cutaneous B-cell lymphomas, immunocytomas and marginal-zone B-cell lymphomas are not life-threatening. Follicle center-cell lymphomas that arise on the head and trunk have also an indolent clinical course (5-year specific survival rates: 94 to 97 p. 100). However, few of these lymphomas are composed of more than 50 p. 100 of large cells with round nuclei (centroblasts and/or immunoblasts) and may have a more aggressive clinical course (5-year specific survival: 72 p. 100). Large B-cell lymphomas of the leg often occur in older patients and have a poorer prognosis (5-year specific survival rate: 52 p. 100). Cases with a single lesion and those with a predominance of large cleaved cells (large centrocytes) have a more favorable clinical course than those with multiple tumors or a round cell morphology.
Conclusion: Clinical, histological and immunophenotypical prognostic factors which have been identified so far may reliably predict the survival outcome in primary cutaneous lymphomas. On this basis, therapeutic guidelines have been proposed. These prognostic data will have to be taken into account when evaluating new potential prognostic factors (e.g. immunophenotypic or molecular) and performing prospective clinical trials.