Epidemiology of cutaneous lymphomas

Primary cutaneous lymphomas represent the second most frequent type of extranodal non-Hodgkin lymphomas (NHLs) after gastrointestinal lymphomas [9]. The worldwide annual incidence of primary cutaneous lymphomas is estimated to be 1:100,000 [1, 6, 9]. Despite the existence of several large, often clinic-based registries dealing with cutaneous lymphomas (Netherlands Lymphoma Registry, Lymphoma Registry Graz/Austria, Lymphoma Registry Stanford/USA, German Registry for Cutaneous Lymphomas, National Cancer Institute’s Surveillance, Epidemiology, and End Results Program (NCI SEER)) there is a paucity of comparable population-based data concerning this group of diseases. Until 2005, one of the main obstacles for the correct reporting was the lack of appropriate classification to cover all clinicopathological entities, when the new WHO-EORTC was introduced [23]. The comparison of age distribution in different lymphoma registries shows that primary cutaneous lymphomas most commonly arise in older adults, with a median onset time after 60 years of age [1]. One exception to this distribution is lymphomatoid papulosis, which often develops in young adults and can even manifest in childhood [2]. Males seem to be more affected than females, with a male/female ratio reaching up to 4:1 [7, 11, 27]