Gamma-delta T-cell lymphoma arising in a long-standing cutaneous plaque.

The precise classification and characterization of primary cutaneous gamma-delta T-cell lymphoma (PCGD-TCL) has been hindered by clinical and morphologic features that overlap with other lymphomas, especially subcutaneous panniculitis-like T cell lymphoma (SPTCL). The recent World Health Organization/European Organization for Research and Treatment of Cancer (WHO/EORTC) classification distinguishes the more aggressive PCGD-TCL from the usually indolent SPTCL, however. We report a 30-year-old woman with an indurated violaceous plaque on the left cheek that had been present for several years. Biopsies showed a dense lymphocytic infiltrate involving the subcutis and dermis that consisted mostly of small and medium-sized lymphocytes, some with irregular nuclear contours and dense chromatin. These cells were positive for TIA-1, TCR-gamma and CD8, but negative for beta-F1 and granzyme-B. Staging with positron emission tomography-computed tomography (PET/CT), CBC and bone marrow with flow cytometry identified lymphadenopathy as well as blood and marrow involvement by an abnormal TCRgd-positive T-cell proliferation (Ann Arbor Stage IV). The patient's history of a long-standing lesion in this case is unusual, in that gamma-delta T-cell lymphomas are typically rapidly progressive neoplasms. As such, it raises the possibility of 'transformation' of a long-standing inflammatory process into an overt lymphoma.