INTRODUCTION: Mycosis fungoides (MF) with large cell transformation (LCT) is an advanced stage of cutaneous lymphoma with a poor prognosis. Identification of LCT is critical and especially challenging when the number of large abnormal lymphocytes is near but below 25%. We propose that Ki-67 and p53 may be useful in making this diagnosis.METHODS: We identified 17 patients with advanced stage (T3 or T4) MF without LCT and 38 patients with a biopsy-confirmed new diagnosis of MF with LCT treated at our institution's cutaneous lymphoma clinic from 2012 to 2016. Seventeen patients underwent 22 biopsies with advanced stage MF (control), and 38 patients with 46 biopsies of MF with LCT were included in this study.RESULTS: The MF cohort had an average CD30 expression of 4%, while the MF-LCT cohort had an average CD30 expression of 22% (P<0.05). The MF cohort had an average Ki-67 staining of 13%, while the MF-LCT group had an average Ki-67 staining of 57% (P<0.05). Forty-seven percent of the MF-LCT group was positive for p53; on the other hand, none of the MF control group showed increased p53 expression (P<0.05).DISCUSSION: While CD30 shows some value in delineating large cell transformation, Ki-67 and p53 appear to be useful immunohistochemical markers in the diagnosis of LCT.
View details for PubMedID 30328119