TNFRSF8 and mycosis fungoides: Large cell transformation is the histopathologic transformation of more than 25% of the neoplastic lymphocytes into clonally identical, larger lymphocytes (example, 4 times the previous size).19 The overall prevalence of LCT among MF patients is reported within the range of 8-55%.20 In our study, LCT was present in 4 patients (5.5%), all of whom were CD30 positive.