Microscopy of T-cell prolymphocytic leukemia. (A) Peripheral blood smear showing 2 medium-sized atypical lymphocytes with round nuclei and prominent nucleoli and abundant basophilic cytoplasms without granules. (B) Cutaneous involvement in T-PLL. Dense dermal infiltrates with marked epidermotropism simulating mycosis fungoides. (C) Bone marrow infiltration by T-PLL with an interstitial infiltration pattern depicted by an immunohistologic stain with an antibody against TCL1. (D) T-cell origin of TCL-1⁺ cells confirmed by immunohistology by double staining with CD5 (red) and TCL1 (brown).