Primary cutaneous CD4⁺small/medium T-cell lymphoproliferative disorder. (A) Patient presenting with a tumor on the left cheek. (B) Detail of atypical dermal infiltrate showing a predominance of small/medium lymphoid cells and scattered large lymphoid cells, which express CD4 (C). (D) Expression of CD279/PD-1 by medium-sized to large atypical T cells, partly arranged in clusters. Original magnification ×200 (B,D) and ×40 (C); hematoxylin and eosin (B) and immunoperoxidase (C-D) stain.