The association of Greig syndrome and mastocytosis reveals the involvement of the hedgehog pathway in advanced mastocytosis.

Mastocytosis is a heterogeneous disease characterized by an abnormal accumulation of mast cells (MCs) in 1 or several organs. Although a somatic KIT D816V mutation is detected in ∼85% of patients, attempts to demonstrate its oncogenic effect alone have repeatedly failed, suggesting that additional pathways are involved in MC transformation. From 3 children presenting with both Greig cephalopolysyndactyly syndrome (GCPS, Mendelian Inheritance in Man [175700]) and congenital mastocytosis, we demonstrated the involvement of the hedgehog (Hh) pathway in mastocytosis. GCPS is an extremely rare syndrome resulting from haploinsufficiency of GLI3, the major repressor of Hh family members. From these familial cases of mastocytosis, we demonstrate that the Hh pathway is barely active in normal primary MCs and is overactive in neoplastic MCs. GLI3 and KIT mutations had a synergistic, tumorigenic effect on the onset of mastocytosis in a GCPS mouse model. Finally, Hh inhibitors suppressed neoplastic MC proliferation in vitro and extend the survival time of mice with aggressive systemic mastocytosis (ASM). This work revealed, for the first time, the involvement of Hh signaling in the pathophysiology of mastocytosis and demonstrated the cooperative effects of the KIT and Hh oncogenic pathways in mice with ASM, leading to the identification of new promising therapeutic targets.

Paediatric mastocytosis: long-term follow-up of 53 patients with whole sequencing of KIT. A prospective study.

BACKGROUND: Mastocytosis is a heterogeneous group of clinical disorders characterized by the abnormal accumulation of mast cells. The adult and paediatric forms differ in their clinical and genetic features and outcomes. OBJECTIVES: To describe the clinical evolution of a well-characterized cohort of paediatric mastocytosis (PM), and to analyse the relationship between KIT mutation and the clinical course. METHODS: This was a prospective cohort study performed at the National Clinical Reference Center for Mastocytosis. Diagnosis was confirmed by identification of KIT mutation on lesional skin biopsy. Mastocytosis subtype, mast cell mediator-related symptoms (MC MRS) and clinical course were recorded. Fifty-three patients with PM and > 4 years of disease course were enrolled. The mean ± SD age at the final evaluation was 13·2 ± 4·8 years. The main outcome was the type of KIT mutation as a predictor of evolution and clinical characteristics. RESULTS: Patients presented with maculopapular cutaneous mastocytosis (n = 44), diffuse cutaneous mastocytosis (n = 6) or mastocytoma (n = 3). The mean duration of disease was 12·1 years. Substantial or partial cutaneous regression (18 of 53 and 16 of 53), stabilization or aggravation (16 of 53) and complete cutaneous regression (three of 53) were noted. MC MRS mainly regressed (21 of 53). For 22 patients, evolution of MC MRS and evolution of cutaneous lesions were different. No significant association between evolution and KIT mutation or between evolution and type of cutaneous mastocytosis was found. A late onset of the disease (after 2 years) is associated with worse evolution. CONCLUSIONS: PM is not systematically self-regressive. MC MRS manifestations and cutaneous lesions can persist or increase overtime. KIT mutation is not a predictor of evolution.

Paediatric mastocytosis: a systematic review of 1747 cases.

Paediatric mastocytosis was previously considered to be a benign and spontaneously regressing disease. However, this evolution is impossible to predict. To clarify the characteristics and course of paediatric mastocytosis, we performed a literature review of 1747 cases published between 1950 and April 2014. Lesions occurred before the age of 2 years in 90% of cases, and presented as urticaria pigmentosa (75% of cases), mastocytoma (20%) or diffuse cutaneous mastocytosis (5%). The male-to-female ratio was 1·4. KIT D816V mutation was detected in 34% of 215 tested patients. Clinical regression (complete or partial) occurred in 67% of cases and stabilization in 27%. However, the outcome was fatal in 2·9% of patients.

Atopic dermatitis burden scale: creation of a specific burden questionnaire for families.

BACKGROUND: The notion of individual burden, associated with a disease, has been introduced to determine the 'disability' in the broadest sense (psychological, social, economic and physical). Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases with an estimated prevalence of 5%-30% in children. OBJECTIVE: To develop and validate a specific questionnaire which assess the burden of families of children with AD: the Atopic dermatitis Burden Scale (ABS). METHODS: Items for inclusion in ABS were initially generated from a literature review and a verbatim report from parents whose child had AD. ABS was refined via item reduction according to interquestion correlations, consensus among experts and exploratory factor analysis. Internal consistency was determined by calculating the Cronbach's α, concurrent validity by calculating the correlation between ABS and the Short-Form 12 items. Discriminant validity was analysed according to the severity degrees of AD assessed by Patient-Oriented SCORing index of Atopic Dermatitis (PO-SCORAD). RESULTS: From an initial list of 29 items, ABS was reduced to a 14-item questionnaire, grouped into four dimensions based on the exploratory factor analysis. Construct validity was demonstrated and ABS showed good internal coherence (Cronbach's α: 0.78). ABS was significantly correlated to the mental dimension of Short-Form 12 (r = -0.49), but it was not correlated to the physical dimension (r = 0.04). ABS scores were significantly different according to the severity degrees of AD, with higher ABS score in parents whose child had severe AD. CONCLUSION: The ABS questionnaire is a validated tool for assessing the burden of families of children with AD. An implementation of a prospective study is planned to estimate sensitivity to change and to confirm its domain structure in larger samples.

[An atypical presentation of Kikuchi-Fujimoto disease]. / Maladie de Kikuchi-Fujimoto: une présentation atypique.

INTRODUCTION: Histiocytic necrotizing lymphadenitis (Kikuchi-Fujimoto disease) is a rare clinical entity characterized by the association of enlarged lymph nodes in the posterior cervical region and fever. The disease is more frequent in young women. CASE REPORT: We report a 41-year-old African patient who presented with atypical features of Kikuchi's disease including cutaneous lupus, haemophagocytosis, and lymphocytic meningitis. The ethnic origin and the clinical presentation were initially suggestive of tuberculous meningitis. However, microbiological analyses remained negative, histological findings were suggestive of Kikuchi's disease and HHV6 DNA integration was documented in our patient. CONCLUSION: Kikuchi's disease should be suspected in an African patient when lymphocytic meningitis is associated with enlarged cervical lymph nodes, hemophagocytosis and HHV6 DNA integration.