Pustular mycosis fungoides has a poor outcome: a multicentric clinico-pathological and molecular case series study.

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.

Subcutaneous Panniculitis-Like T-Cell Lymphoma Revealed By Immunophenotyping of Necrosis.

ABSTRACT: Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare but well-defined entity, often associated with autoimmune manifestations, generally with a good prognosis unless associated with hemophagocytic syndrome. Typically, the lymphoma cells rim the adipocytes and are characterized by a CD8 + cytotoxic phenotype. We report 2 cases of SPTCL where the first biopsies only showed subcutaneous fat necrosis without any lymphoma cell visible. The diagnoses were allowed by immunophenotypic markers which characterized necrotic neoplastic T cells and confirmed on further biopsies with a typical pattern of SPTCL. These observations should prompt dermatologists to perform as large biopsies as possible, and pathologists to perform immunophenotyping in all suspected cases even if only lobular necrosis is seen morphologically.

Severe blistering eruptions induced by immune checkpoint inhibitors: a multicentre international study of 32 cases.

Among dermatologic adverse events induced by immune checkpoint inhibitors (ICI), bullous life-threatening reactions are rare. To better define the clinical and histological features, treatment, and prognosis of ICI-related severe blistering cutaneous eruptions. This retrospective case series was conducted between 2014/05/15 and 2021/04/15 by the dermatology departments of four international registries involved in drug reactions. Inclusion criteria were age ≥18 years old, skin eruption with blisters with detachment covering ≥1% body surface area and at least one mucous membrane involved, available pictures, and ICI as suspect drug. Autoimmune bullous disorders were excluded. Each participant medical team gave his own diagnosis conclusion: epidermal necrolysis (EN), severe lichenoid dermatosis (LD), or unclassified dermatosis (UD). After a standardized review of pictures, cases were reclassified by four experts in EN or LD/UD. Skin biopsies were blindly reviewed. Thirty-two patients were included. Median time to onset was 52 days (3-420 days). Cases were originally diagnosed as EN in 21 cases and LD/UD in 11 cases. After review by experts, 10/21 EN were reclassified as LD/UD. The following manifestations were more frequent or severe in EN: fever, purpuric macules, blisters, ocular involvement, and maximal detachment. Most patients were treated with topical with or without systemic corticosteroids. Eight patients (25%) died in the acute phase. The culprit ICI was not resumed in 92% of cases. In three patients, another ICI was given with a good tolerance. Histology did not reveal significant differences between groups. Severe blistering cutaneous drug reactions induced by ICI are often overdiagnosed as EN. Consensus for management is pending.