A, Mycosis fungoides (MF), plaque stage with high expression of HDAC1 in the nuclei of the lymphoid infiltrate. Note that HDAC1 is also expressed in the nuclei in epithelial cells of the epidermis. B, Cutaneous T-cell lymphoma (CTCL), unspecified with high expression of HDAC2 in the nuclei of the neoplastic cells. C, MF, tumour stage with high HDAC6 expression in the cytoplasm. Note that HDAC6 is also expressed in the cytoplasm of epithelial cells of the epidermis. D, MF, tumour stage, negative of HDAC6 in the lymphoid infiltrate. E, CTCL, unspecified with high acetylation of histone H4. Small reactive lymphoid cells are negative. F, Precursor plasmacytoid dendritic cell neoplasm negative for H4 acetylation.