Porokeratosis Causing Change in Melanocytic Nevi

Large cell transformation of mycosis fungoides (MF) is an uncommon phenomenon. We present a case of CD30‐positive large cell transformation and discuss its possible pathophysiology. A 74 year‐old male with a 36‐year history of patch stage MF presented with a 3‐month history of right chest cellulitis that was refractory to IV antibiotic treatment. Skin biopsies from his thigh demonstrated a patchy dermal infiltrate of irregular and hyperchromatic lymphocytes and epidermotropism. The majority of the infiltrate was positive for CD4, CD3, CD2, and negative for CD7. Only 10% were positive for CD25 and CD8. Biopsies obtained from the ulcerated chest nodules showed a dermal infiltrate of large and pleomorphic lymphoid cells with prominent nucleoli. These large lymphoid cells were strongly positive for CD3, CD30, CD25, CD2 and UCHL‐1. Occasional cells were positive for CD4 and CD20. They were negative for ALK‐1, TIA‐1, CD7, CD8, and CD15. T‐gamma receptor gene rearrangement analyses by polymerase chain reaction demonstrated a clonal process with similar rearrangement patterns identified in the patch stage MF as well as in large cell transformation areas. Examinations of his peripheral blood and bone marrow were negative. The patient had tolerated one cycle of CHOP chemotherapy.