Rationale and Objective Primary cutaneous lymphomas are a rare and diverse group of cancers that start in the skin. While international data suggests an increase in cases since the 1970s, there is currently a lack of nationwide data in Italy regarding how common these diseases are and how they correlate with environmental or social factors.The main goal of this study is to create a national map of cutaneous lymphoma incidence and prevalence in Italy. Researchers want to identify if there are specific geographic areas with higher or lower numbers of cases and investigate potential links between the disease and environmental pollutants or other health conditions (comorbidities).Study Design This is a multicenter observational study that looks at both past and future data (retrospective and prospective). The study will involve approximately 1,000 patients across several Italian dermatology departments, with the IRCCS Azienda Ospedaliero-Universitaria di Bologna serving as the coordinating center.What the Study InvolvesData Collection: Researchers will review medical records from January 1, 2018, to December 31, 2022 (retrospective phase) and continue to collect data for patients enrolled over the next three years.Patient Participation: Patients will follow their standard clinical care paths. Information collected includes medical history, current and previous therapies, and laboratory results.Follow-up: Participants will be monitored for approximately two years to evaluate clinical outcomes and treatment responses.Expected Outcomes By analyzing this data, the study aims to improve clinical practice by providing a clearer understanding of how cutaneous lymphoma affects the Italian population based on age, sex, ethnicity, and location.

The primary objective of this multicenter, national, exploratory observational study is to establish a comprehensive epidemiological map of primary cutaneous lymphomas (PCLs) within the Italian territory, addressing the current lack of a centralized national registry. PCLs are defined as a heterogeneous group of extranodal lymphomas that present exclusively in the skin at the time of diagnosis and remain confined to the skin for at least six months thereafter. This study investigates the incidence and prevalence of these rare malignancies, which are characterized by distinct clinical, histopathological, immunophenotypic, and molecular profiles, noting that cutaneous T-cell lymphomas generally exhibit a higher frequency than B-cell variants. By utilizing a combined retrospective and prospective cohort design, the investigators aim to identify potential correlations between the onset of cutaneous lymphoma and various external factors, including geographic clusters of high or low incidence and exposure to environmental pollutants. The retrospective phase involves a systematic review of medical records for patients diagnosed between January 1, 2018, and December 31, 2022, while the prospective phase entails the enrollment of new patients over a three-year period following Institutional Review Board approval.

The study population consists of approximately 1,000 patients across participating Italian dermatology departments, with the Dermatology Unit of the IRCCS Azienda Ospedaliero-Universitaria di Bologna serving as the coordinating center. Eligible participants include male and female patients older than two years of age with a confirmed diagnosis of cutaneous lymphoma who provide informed consent. Clinical data collection is integrated into standard care pathways, encompassing detailed medical histories, prior and current therapeutic interventions, laboratory results, and specialized diagnostic examinations. These data points are utilized to calculate the absolute frequency of PCLs based on center-specific patient volumes and to stratify various lymphoma subgroups by age, sex, and ethnicity. Secondary endpoints focus on identifying clinical associations between specific comorbidities and disease onset, as well as evaluating longitudinal treatment responses and clinical outcomes over a two-year follow-up period.

Data management is conducted through the REDCap (Research Electronic Data Capture) electronic platform to ensure pseudonymization and secure storage. Statistical analysis is performed by an independent statistician using descriptive statistics including means, medians, and standard deviations for continuous variables, alongside frequencies and percentages for categorical data. Comparative analyses employ Chi-square or Fisher's exact tests for categorical variables, and Student's t-test, ANOVA, or Mann-Whitney U tests for continuous variables, depending on the distribution of the data. This rigorous methodological framework is designed to provide high-quality evidence regarding the clinico-pathological characteristics of PCLs in Italy, ultimately aiming to improve clinical practice and public health strategies through peer-reviewed publications and scientific dissemination.

Inclusion Criteria:

• Patients over 2 years of age
• Patients with cutaneous lymphoma
• Obtaining informed consent

Exclusion Criteria:

• NA

The study population will include both male and female patients diagnosed with cutaneous lymphoma since January 1, 2018. It is estimated that approximately 1,000 patients will be enrolled, 300 of whom are expected to be recruited from the Dermatology Unit of the IRCCS AOUBO