RESUMO
BACKGROUND: Mycosis fungoides (MF) has usually an indolent course. However, some patients develop a more aggressive disease and few prognostic parameters have been identified. Isolated cases of pustular MF (pMF) suggest an unfavourable prognosis. OBJECTIVES: We aim to describe the clinico-pathological characteristics and prognostic value of pMF. METHODS: We retrospectively collected data of all cases of MF with histological pustules diagnosed from 2009 to 2020. The outcomes and clinico-pathological characteristics of pMF at diagnosis (pMFD) were compared to those of a cohort of non-pustular MF (NpMF). RESULTS: 33 pMF (including 22 pMFD) and 86 NpMF cases were included. The median age at diagnosis of pMF was 61 years [IQR=50-75]. The median follow-up of pMFD was 32 months [IQR=14-49]. Clinically, 33% of pMF had pustules. Large-cell transformation (LCT) occurred in 17 cases. pMFD were at a significantly more advanced-stage and more showed LCT at diagnosis than NpMF (50% vs 7%, p<0.001 and 23% vs 0%, p<0.001, respectively). In multivariate Cox analysis, the presence of histological pustule at diagnostic was associated with shorter OS in all patients (HR=13.90, CI95%[2.43-79]; p=0.003), and in early-stage patients (HR=11.09, CI95%[1.56-78.82]; p=0.02). In multivariate Fine and Gray model analysis, pMFD was associated with a higher cumulative incidence of LCT (SHR=13.90, CI95% [2.43-79]; p=0.003) in all patients. Median OS after the occurrence of histological pustules during follow-up of all pMF patients was 37 months, with a five-year OS of 25% (CI95% [0.06-0.5]). CONCLUSION: pMF often follows an aggressive course, with a high risk of LCT and shorter survival, even for early-stage patients. Histological pustules at diagnostic of MF might represent an independent poor prognostic factor, to be confirmed by further studies. Because pustules are not always clinically identified, histological pustules should be mentioned in pathology reports of MF and prompt discussion of a closer follow-up.
RESUMO
Angioimmunoblastic T cell lymphoma (AITL) is a peripheral T cell lymphoma that originates from T follicular helper (Tfh) cells and exhibits a prominent tumor microenvironment (TME). IDH2 and TET2 mutations co-occur frequently in AITL, but their contribution to tumorigenesis is poorly understood. We developed an AITL mouse model that is driven by Idh2 and Tet2 mutations. Malignant Tfh cells display aberrant transcriptomic and epigenetic programs that impair TCR signaling. Neoplastic Tfh cells bearing combined Idh2 and Tet2 mutations show altered cross-talk with germinal center B cells that promotes B cell clonal expansion while decreasing Fas-FasL interaction and reducing B cell apoptosis. The plasma cell count and angiogenesis are also increased in the Idh2-mutated tumors, implying a major relationship between Idh2 mutation and the characteristic AITL TME. Our mouse model recapitulates several features of human IDH2-mutated AITL and provides a rationale for exploring therapeutic targeting of Tfh-TME cross-talk for AITL patients.