Transformation of cutaneous T-cell lymphoma. (A) Lymph node biopsy shows a pleomorphic tumor with large to anaplastic nucleolated cells admixed with small lymphocytes with markedly irregular nuclei. The patient had a 10-year history of plaque-type mycosis fungoides before developing nodal transformation. (B) OX40/CD134 immunostain is positive primarily in medium-sized to large cells. (C) CD30 immunostain highlights occasional anaplastic cells with membrane and perinuclear staining.