Primary Cutaneous Gamma-Delta T-Cell Lymphoma

**Semantic type:** Neoplastic Process

**Definition:** An aggressive cutaneous lymphoma of mature, activated gamma/delta T-lymphocytes. It usually presents with disseminated plaques and nodules. Involvement of mucosal sites is frequent. However, involvement of lymph nodes, spleen, or bone marrow is uncommon. Morphologically, there are three patterns of cutaneous involvement: epidermotropic, dermal, and subcutaneous. Often, more than one pattern may co-exist in a single biopsy specimen, or may be present in different biopsy specimens from the same patient. The lymphocytic infiltrate is composed of medium- to large-sized lymphocytes expressing CD56. Most cases lack both CD4 and CD8, although CD8 may be present in some cases. This group of lymphomas includes cases previously known as subcutaneous panniculitis-like T-cell lymphoma with a gamma/delta phenotype.

**Synonyms:** - Cutaneous Gamma/Delta T-Cell Lymphoma - PCGD-TCL - Peripheral Gamma-Delta T-Cell Lymphoma - Primary cutaneous gamma-delta T-cell lymphoma