Mycosis fungoides with large cell transformation: clinicopathological features and prognostic factors

Large cell transformation of mycosis fungoides (MF-LCT) occurs in 20-50% of advanced MF, and is generally associated with poor prognosis, although some patients have indolent disease. We sought to identify clinicopathological prognostic factors in a large number of patients with MF-LCT.We identified patients with MF-LCT treated between 1991 and 2012 at a referral centre for cutaneous lymphoma. Clinical and pathological records, and histopathological slides were reviewed. Associations of clinicopathological variables with disease-specific survival were analysed.In 51 patients with MF-LCT, factors significantly associated with shorter survival were: age >60 years (25 versus 61  months, p = 0.01), stage III/IV (25 versus 44  months, p = 0.049), high serum lactate dehydrogenase (LDH; 24 versus 53  months, p = 0.007), absent papillary dermal involvement (8 versus 30  months, p = 0.008); follicular mucin at transformation (24 versus 42  months, p = 0.007); and the absence of fibrosis at transformation (21 versus 42  months, p = 0.03). Patients presenting with transformation at diagnosis had better survival than those who started with a small cell phenotype (p = 0.02). Age >60 years was independently associated with poorer survival (HR 5.61, 95%CI 1.17-26.8, p = 0.03), and the presence of fibrosis at transformation was independently associated with improved survival (HR 0.30, 95%CI 0.09-0.97, p = 0.045).In patients with MF-LCT, clinical features (age, stage, serum LDH) are important in assessing prognosis. Additional clinical and pathological features identified in this study may also assist in prognostic stratification. Studies of larger cohorts should be performed to validate the prognostic significance of these features.