Cutaneous T-cell lymphomas with panniculitis-like histologic features have different clinical courses depending on whether they are composed of αβ T cells or γδ T cells, necessitating their distinction for proper prognostication. However, unlike αβ T cells, γδ T cells cannot be reliably detected in formalin-fixed, paraffin-embedded sections. We demonstrated that a commercially available antibody can detect γδ T cells and examined 2 cases of flow cytometry-proven γδ T-cell lymphomas and 15 control cases of nonneoplastic panniculitis. In both lymphomas, the atypical lymphocytes were γδ T cells, whereas the reactive lymphocytes were αβ T cells. In contrast, nonneoplastic panniculitis had predominantly αβ T cells with many fewer and individually scattered γδ T cells. The detection of γδ T cells in paraffin sections provides a powerful new tool to characterize T cells in lymphomas and inflammation. © American Society for Clinical Pathology.