Histological transformation in Splenic Marginal Zone Lymphoma (t-SMZL) represents an unmet clinical and biological need, invariably associated with poor prognosis and reduced overall survival. At the present time, there are no recommended treatments intended specifically to t-SMZL and little is known about t-SMZL genetic complexity. The aim of this study is to provide information that will help clinicians to better understand the complexity of the disease. The information gained from this study will also lead to more specific and effective treatment for patients with t-SMZL.

Already existing and coded tumor biological material and health-related patient data will be retrospectively collected from institutional biobanks and patients' charts or electronic medical records upon receipt of ethical approval. Each patient enrolled in the study will be assigned a unique identification numerical code upon registration in the study. The unique identification code will be used to record health-related data and to label biological samples. Health-related data will be collected by electronic case report form (e-CRF) system. Data quality will be insured by query generation.

Annotated baseline features will include: date of diagnosis, date and tissue type of histological sample collected at diagnosis (spleen and/or bone marrow), age, gender, Eastern Cooperative Oncology Group - Performing Status (ECOG-PS), Ann Arbor stage, Lactate Dehydrogenase (LDH), number and location of extranodal sites, bone marrow involvement and percentage, peripheral blood involvement, bulky disease (>7 cm), number of nodal sites, B symptoms, hemoglobin, platelets, lymphocytes, beta-2-microglobulin, albumin, Hepatitis C Virus (HCV) infection, serum paraprotein and type.

Annotated follow-up features will include: the date of progression to a disease requiring treatment, type of first line treatment, date of start of the first line treatment, date of progression after first line treatment, date of the second line treatment, type of second line treatment.

Annotated transformation features will include: date of transformation, date and type of histological sample collected at transformation (spleen and/or bone marrow and/or lymph node and/or other site), histological transformation type and relative molecular data (if available), ECOG-PS, Ann Arbor stage, LDH, number and location of extranodal sites, bone marrow involvement and percentage, peripheral blood involvement, bulky disease (>7 cm), number of nodal sites, B symptoms, hemoglobin, platelets, lymphocytes, beta-2-microglobulin, albumin, serum paraprotein, and type.

Survival features will include the date of death, cause of death, date of last follow-up.

Mutation analysis, immunoglobulin gene rearrangement analysis, copy number aberration analysis, structural variant analysis, and DNA methylation profile will be performed by Next Generation Sequencing (NGS) of genomic DNA extracted from the biological sample available for the analysis. Gene expression will be assessed by NGS of RNA extracted from from the biological sample available for the analysis.

Inclusion Criteria:

1. Adults aged 18 years or older, regardless of the gender;
2. Diagnosis of HT of SMZL (both at baseline, co-occurring with diagnosis of SMZL, or during the natural history of the disease);
3. Availability of diagnostic tumor material (either frozen or FFPE) from spleen, lymph node, extra nodal site, peripheral blood or bone marrow collected at the time of histological transformation. Tumor material (either frozen or FFPE), from spleen, peripheral blood or bone marrow, collected at the time of SMZL diagnosis will be also collected, if available;
4. Availability of the baseline and follow-up annotations.

Exclusion Criteria:

• None

Adult patients with transformed SMZL