Clinical spectrum of indolent mycosis fungoides with a gamma‐delta (γδ) phenotype: a single institution review including therapy and outcomes

Abstract Background Primary cutaneous γδ T‐cell lymphoma (CGD‐CTL) is a rare malignancy that classically exhibits an aggressive clinical phenotype. Objectives Review cases of mycosis fungoides with a γδ phenotype that demonstrated an indolent clinical course. Methods Retrospective review of patients diagnosed with MF with a γδ phenotype and an indolent clinical course between 2018 and 2022 treated at the University of Utah. Results Five patients ages 4‐81 years old were identified. All presented with clinically persistent patch or plaque‐stage disease, and histopathology showed primarily epidermotropic infiltrates positive for TCR delta via immunostaining. None of these patients have required aggressive treatment with multiagent chemotherapy. Conclusions There exists a subset of indolent CGD‐TCL patients who are clinicopathologically distinct from classic CGD‐CTL and clinically resembling indolent MF. Therefore, we prefer the term “MF with γδ phenotype” for these rare cases.