A retrospective cohort of cases diagnosed between 2010 and 2024, assembled from medical-record data.

Target enrollment: 1,300-1,500 patients.

A prospective cohort of patients newly diagnosed between 2025 and 2030, ensuring ≥5-year follow-up for all survivors.

Target sample size: 1,000-1,500 cases, estimated from participating centers' annual diagnostic volumes over a 5-year accrual period. The cohort should be multidimensionally representative, including: (i) geographic coverage across North, East, South, Southwest, and Northeast China; (ii) hospital tiers with tertiary ("Class III Grade A") institutions as the core and selective inclusion of prefecture-level hospitals; and (iii) economic diversity spanning regions with differing levels of socioeconomic development.

Observational

The number and percentage of participants diagnosed with each specific subtype of Peripheral T-Cell Lymphoma (e.g., PTCL-NOS, AITL, ALCL, ENKTL, etc.). Diagnosis is confirmed by pathological review based on the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues (Revised 4th edition, 2017).

OS is defined as the time from the date of pathological diagnosis to the date of death from any cause. For patients who are lost to follow-up, survival time will be censored at the date of last contact.

PFS is defined as the time from the date of pathological diagnosis to the date of the first documented disease progression (PD) or death from any cause, whichever occurs first. Disease progression is assessed based on the investigator's evaluation of radiological and clinical data.

Evaluation of the number and percentage of participants carrying specific genetic alterations. Key biomarkers to be assessed include:

Gene Mutations: TET2, DNMT3A, IDH2, RHOA, TP53, EZH2, and genes related to the PI3K-AKT pathway, assessed by Next-Generation Sequencing (NGS) or ct-DNA analysis. Correlations between these biomarkers and clinical outcomes (response, survival) will be analyzed.