Mycosis Fungoides : Transformation
Large Cell Transformation in Mycosis Fungoides (MF): The transformed large cells have a blast-like appearance with vesicular nuclei and prominent nucleoli. Mitotic activity is brisk. There may be considerable nuclear pleomorphism as well as Reed-Sternberg-like cells. The tumor immunophenotype is that of typical MF. The cells are usually CD4+ and may show loss of CD2, CD5, and CD7. CD8+ variants occur. They may acquire expression of cytotoxic molecules such as perforin, granzyme B, and TIA-1. Less frequently expressed antigens include CD30 (30-50% of cases), CD25, and CD20. CD30-positive transformation of MF can be distinguished from both cutaneous ALCL and lymphomatoid papulosis on clinical grounds.