The aim of this study is to retrospectively collect clinical information on patients with extranodal or rare lymphomas, and to explore the best treatment strategy for these lymphomas in the real-world population.

Lymphoma is a highly common malignant tumor in Asia. For specific extra-abdominal sites or rare pathological subtypes of lymphoma, traditional chemotherapy protocols often cannot provide satisfactory results for patients. This study aims to retrospectively collect clinical information on patients with extranodal lymphoma or rare pathological subtype lymphoma, including the distribution of involved sites, clinical and molecular characteristics of different lymphoma subtypes, clinical treatment protocols, and prognosis, to explore the best treatment strategy for these lymphomas in the real-world population.

Inclusion Criteria:

1. Age ≥ 18 years (including 18 years old).
2. Patients newly diagnosed with non-Hodgkin lymphoma with extranodal involvement, whether it is primary, secondary, or cannot be determined; Or patients newly diagnosed with non-Hodgkin lymphoma of rare pathological types, including IVLBCL, SMZL, ALCL, AITL, MALTL.
3. Patients who have received systematic clinical treatment.
4. Patients with measurable lesions, at least containing one effective evaluation of efficacy.

Exclusion Criteria:

1. Patients who only receive supportive treatment.
2. Patients who cannot obtain effective evaluation data of efficacy.

Adult patients with histologically confirmed diagnosis of non-Hodgkin lymphoma with extranodal involvement or non-Hodgkin lymphoma of rare pathological types attending participating centres.