Primary Cutaneous Gamma-Delta T-Cell Lymphoma
Associated Genetic Biomarkers
NCI 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. 
Primary cutaneous gamma-delta T-cell lymphomas most frequently harbor alterations in ROBO1, CDKN2B, CDKN2A, XPO1, and TSC1 .
CDKN2B Loss, CDKN2A Loss, XPO1 Amplification, TSC1 S505L, and TSC1 Mutation are the most common alterations in primary cutaneous gamma-delta T-cell lymphoma .
There are 4 clinical trials for primary cutaneous gamma-delta T-cell lymphoma, of which 4 are open and 0 are completed or closed. Of the trials that contain primary cutaneous gamma-delta T-cell lymphoma as an inclusion criterion, 1 is phase 1/phase 2 (1 open) and 3 are phase 2 (3 open).
TNFRSF8 is the most frequent gene inclusion criterion for primary cutaneous gamma-delta T-cell lymphoma clinical trials .
Epoch regimen, brentuximab vedotin, and carboplatin are the most common interventions in primary cutaneous gamma-delta T-cell lymphoma clinical trials.
2. The AACR Project GENIE Consortium. AACR Project GENIE: powering precision medicine through an international consortium. Cancer Discovery. 2017;7(8):818-831. Dataset Version 8. This dataset does not represent the totality of the genetic landscape; see paper for more information.