• Written informed consent

• Adequate fresh or archival tumor biopsy or intent to obtain fresh tumor biopsy.

• Pathologically-confirmed mature T- or natural killer (NK)-cell lymphoma meeting one of the following diagnostic criterion (based on WHO classification and NCCN guidelines):

‣ T-cell prolymphocytic leukemia

⁃ T-cell large granular lymphocytic leukemia

⁃ Chronic lymphoproliferative disorder of NK cells

⁃ Aggressive NK-cell leukemia

⁃ Systemic Epstein-Barr virus (EBV)-positive T-cell lymphoma of childhood

⁃ Chronic active EBV infection of T- and NK-cell type, systemic form

⁃ Hydroa vacciniforme-like lymphoproliferative disorder

⁃ Adult T-cell leukemia/lymphoma

⁃ Extranodal NK/T-cell lymphoma, nasal type

⁃ Enteropathy-associated T-cell lymphoma

⁃ Monomorphic epitheliotropic intestinal T-cell lymphoma

⁃ Intestinal T-cell lymphoma, not otherwise specified (NOS)

⁃ Indolent T-cell lymphoproliferative disorder of the gastrointestinal tract

⁃ Hepatosplenic T-cell lymphoma

⁃ Subcutaneous panniculitis-like T-cell lymphoma

⁃ Mycosis fungoides (limited to those with ≥ stage IB disease and those receiving active therapy)

⁃ Sézary syndrome

⁃ Primary cutaneous anaplastic large cell lymphoma (receiving systemic therapy)

⁃ Primary cutaneous Gamma-Delta T-cell lymphoma

⁃ Primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma

⁃ Primary cutaneous acral CD8+ T-cell lymphoma (receiving systemic therapy)

⁃ Peripheral T-cell lymphoma, not otherwise specified

⁃ Angioimmunoblastic T-cell lymphoma

⁃ Follicular T-cell lymphoma

⁃ Nodal peripheral T-cell lymphoma with TFH phenotype

⁃ Anaplastic large cell lymphoma, ALK-positive

⁃ Anaplastic large cell lymphoma, ALK-negative

⁃ Breast-implant associated anaplastic large cell lymphoma.

• NOTE: Patients with diagnoses of mycosis fungoides, primary cutaneous anaplastic large cell lymphoma, and/or primary cutaneous acral CD8+ T-cell lymphoma must be receiving systemic therapy.