Incidence and ten-year follow-up of primary cutaneous lymphomas: a single-centre cohort study.

BACKGROUND: Primary cutaneous lymphomas (PCLs) are a rare group of extranodal non-Hodgkin lymphomas, and epidemiological data in Mediterranean countries are scarce.

OBJECTIVE: To investigate the incidence and characteristics of PCL in a single tertiary referral centre in Italy.

MATERIALS & METHODS: A total of 141 PCL patients, seen over a 10-year follow-up period, were investigated.

RESULTS: Incidence rate of PCL was 0.8 cases/100,000 person years. T-cell lymphoma represented 78.7% of all cases, the majority being early mycosis fungoides (MF) (64%; median age: 66 years), followed by lymphomatoid papulosis (LyP) (19%; median: age 48 years), and others (median age: 72 years), including eight cases of anaplastic large CD30+ T-cell lymphoma, four CD4+ small-medium pleomorphic T-cell lymphoproliferative disorder, four Sézary syndrome, one subcutaneous panniculitis-like T-cell lymphoma, one extranodal NK/T-cell lymphoma nasal-type, and one angioimmunoblastic T-cell lymphoma. B-cell lymphoma accounted for 21.3% of PCL, with 20 cases of cutaneous follicular centre B-cell (median age: 63 years), four primary cutaneous marginal zone, three primary cutaneous diffuse large B-cell, and three leg-type lymphoma. Complete remission within the first year after diagnosis occurred in 70.4% of MF, 61.9% of LyP, 78.9% of other T-cell lymphoma, and 93.1% of B-cell lymphoma cases. Based on a Cox proportional hazard regression model, age, gender, stage, and lactate dehydrogenase and β2-microglobulin blood levels did not predict clinical remission of MF or LyP.

CONCLUSIONS: The incidence and characteristics of PCL in Italy are similar to those in other European countries. PCLs may be diagnosed at very early stages with good prognosis.