Characterization of CD34+ hematopoietic cells in systemic mastocytosis: Potential role in disease dissemination.

BACKGROUND: Recent studies show that most systemic mastocytosis (SM) patients, including indolent SM (ISM) with (ISMs+) and without skin lesions (ISMs-), carry the KIT D816V mutation in PB leukocytes. We investigated the potential association between the degree of involvement of BM hematopoiesis by the KIT D816V mutation and the distribution of different maturation-associated compartments of bone marrow (BM) and peripheral blood (PB) CD34+ hematopoietic precursors (HPC) in ISM and identified the specific PB cell compartments that carry this mutation. METHODS: The distribution of different maturation-associated subsets of BM and PB CD34+ HPC from 64 newly diagnosed (KIT-mutated) ISM patients and 14 healthy controls was analyzed by flow cytometry. In 18 patients, distinct FACS-purified PB cell compartments were also investigated for the KIT mutation. RESULTS: ISM patients showed higher percentages of both BM and PB MC-committed CD34+ HPC vs controls, particularly among ISM cases with MC-restricted KIT mutation (ISMMC ); this was associated with progressive blockade of maturation of CD34+ HPC to the neutrophil lineage from ISMMC to multilineage KIT-mutated cases (ISMML ). Regarding the frequency of KIT-mutated cases and cell populations in PB, variable patterns were observed, the percentage of KIT-mutated PB CD34+ HPC, eosinophils, neutrophils, monocytes and T cells increasing from ISMs-MC and ISMs+MC to ISMML patients. CONCLUSION: The presence of the KIT D816V mutation in PB of ISM patients is associated with (early) involvement of circulating CD34+ HPC and multiple myeloid cell subpopulations, KIT-mutated PB CD34+ HPC potentially contributing to early dissemination of the disease.

Increased IL6 plasma levels in indolent systemic mastocytosis patients are associated with high risk of disease progression.

Systemic mastocytosis (SM) is a heterogeneous disease with altered interleukin (IL)-6 and IL13 plasma levels. However, no study has simultaneously investigated the plasma levels of IL1ß, IL6, IL13, CCL23 and clusterin in SM at diagnosis and correlated them with disease outcome. Here we investigated IL1ß, IL6, IL13, CCL23 and clusterin plasma levels in 75 SM patients--66 indolent SM (ISM) and 9 aggressive SM--and analyzed their prognostic impact among ISM cases grouped according to the extent of hematopoietic involvement of the bone marrow cells by the KIT D816V mutation. Although increased IL1ß, IL6 and CCL23 levels were detected in SM patients versus healthy controls, only IL6 and CCL23 levels gradually increased with disease severity. Moreover, increased IL6 plasma levels were associated with ISM progression to more aggressive disease, in particular among ISM patients with multilineal KIT mutation (ISM-ML), these patients also showing a higher frequency of organomegalies, versus other ISM-ML patients. Of note, all ISM patients who progressed had increased IL6 plasma levels already at diagnosis. Our results indicate that SM patients display an altered plasma cytokine profile already at diagnosis, increased IL6 plasma levels emerging as an early marker for disease progression among ISM cases, in particular among high-risk ISM patients who carry multilineage KIT mutation.

KIT mutation analysis in mast cell neoplasms: recommendations of the European Competence Network on Mastocytosis.

Although acquired mutations in KIT are commonly detected in various categories of mastocytosis, the methodologies applied to detect and quantify the mutant type and allele burden in various cells and tissues are poorly defined. We here propose a consensus on methodologies used to detect KIT mutations in patients with mastocytosis at diagnosis and during follow-up with sufficient precision and sensitivity in daily practice. In addition, we provide recommendations for sampling and storage of diagnostic material as well as a robust diagnostic algorithm. Using highly sensitive assays, KIT D816V can be detected in peripheral blood leukocytes from most patients with systemic mastocytosis (SM) that is a major step forward in screening and SM diagnosis. In addition, the KIT D816V allele burden can be followed quantitatively during the natural course or during therapy. Our recommendations should greatly facilitate diagnostic and follow-up investigations in SM in daily practice as well as in clinical trials. In addition, the new tools and algorithms proposed should lead to a more effective screen, early diagnosis of SM and help to avoid unnecessary referrals.

Anaphylaxis as a clinical manifestation of clonal mast cell disorders.

Clonal mast cell disorders comprise a heterogeneous group of disorders characterized by the presence of gain of function KIT mutations and a constitutively altered activation-associated mast cell immunophenotype frequently associated with clinical manifestations related to the release of mast cells mediators. These disorders do not always fulfil the World Health Organization (WHO)-proposed criteria for mastocytosis, particularly when low-sensitive diagnostic approaches are performed. Anaphylaxis is a frequent presentation of clonal mast cell disorders, particularly in mastocytosis patients without typical skin lesions. The presence of cardiovascular symptoms, e.g., hypotension, occurring after a hymenoptera sting or spontaneously in the absence of cutaneous manifestations such as urticaria is characteristic and differs from the presentation of anaphylaxis in the general population without mastocytosis.

Proposed diagnostic algorithm for patients with suspected mastocytosis: a proposal of the European Competence Network on Mastocytosis.

Mastocytosis is an emerging differential diagnosis in patients with more or less specific mediator-related symptoms. In some of these patients, typical skin lesions are found and the diagnosis of mastocytosis can be established. In other cases, however, skin lesions are absent, which represents a diagnostic challenge. In the light of this unmet need, we developed a diagnostic algorithm for patients with suspected mastocytosis. In adult patients with typical lesions of mastocytosis in the skin, a bone marrow (BM) biopsy should be considered, regardless of the basal serum tryptase concentration. In adults without skin lesions who suffer from mediator-related or other typical symptoms, the basal tryptase level is an important parameter. In those with a slightly increased tryptase level, additional investigations, including a sensitive KIT mutation analysis of blood leucocytes or measurement of urinary histamine metabolites, may be helpful. In adult patients in whom (i) KIT D816V is detected and/or (ii) the basal serum tryptase level is clearly increased (>25-30 ng/ml) and/or (iii) other clinical or laboratory features suggest the presence of 'occult' mastocytosis or another haematologic neoplasm, a BM investigation is recommended. In the absence of KIT D816V and other signs or symptoms of mastocytosis or another haematopoietic disease, no BM investigation is required, but the clinical course and tryptase levels are monitored in the follow-up. In paediatric patients, a BM investigation is usually not required, even if the tryptase level is increased. Although validation is required, it can be expected that the algorithm proposed herein will facilitate the management of patients with suspected mastocytosis and help avoid unnecessary referrals and investigations.

Refined diagnostic criteria and classification of mast cell leukemia (MCL) and myelomastocytic leukemia (MML): a consensus proposal.

Mast cell leukemia (MCL), the leukemic manifestation of systemic mastocytosis (SM), is characterized by leukemic expansion of immature mast cells (MCs) in the bone marrow (BM) and other internal organs; and a poor prognosis. In a subset of patients, circulating MCs are detectable. A major differential diagnosis to MCL is myelomastocytic leukemia (MML). Although criteria for both MCL and MML have been published, several questions remain concerning terminologies and subvariants. To discuss open issues, the EU/US-consensus group and the European Competence Network on Mastocytosis (ECNM) launched a series of meetings and workshops in 2011-2013. Resulting discussions and outcomes are provided in this article. The group recommends that MML be recognized as a distinct condition defined by mastocytic differentiation in advanced myeloid neoplasms without evidence of SM. The group also proposes that MCL be divided into acute MCL and chronic MCL, based on the presence or absence of C-Findings. In addition, a primary (de novo) form of MCL should be separated from secondary MCL that typically develops in the presence of a known antecedent MC neoplasm, usually aggressive SM (ASM) or MC sarcoma. For MCL, an imminent prephase is also proposed. This prephase represents ASM with rapid progression and 5%-19% MCs in BM smears, which is generally accepted to be of prognostic significance. We recommend that this condition be termed ASM in transformation to MCL (ASM-t). The refined classification of MCL fits within and extends the current WHO classification; and should improve prognostication and patient selection in practice as well as in clinical trials.

Current state of biology and diagnosis of clonal mast cell diseases in adults.

Mastocytosis comprises a heterogeneous group of disorders characterized by the presence of clonal mast cells (MC) in organs such as skin, bone marrow (BM), and gastrointestinal tract, among other tissues. The clonal nature of the disease can be established in most adult patients by the demonstration of activating KIT mutations in their BM MC. When highly sensitive techniques capable of identifying cells present at very low frequencies in a sample are applied, BM MC from virtually all systemic mastocytosis patients display unique immunophenotypical features, particularly the aberrant expression of CD25. By contrast, large, multifocal BM MC aggregates (the only World Health Organization major criterion for systemic mastocytosis) are absent in a significant proportion of patients fulfilling at least three minor criteria for systemic mastocytosis, particularly in subjects studied at early stages of the disease with very low MC burden. Moreover, recent molecular and immunophenotypical investigations of BM MC from patients with indolent systemic mastocytosis have revealed a close association of some biological features (e.g., multilineage involvement of hematopoiesis by the KIT mutation and an immature mast cell immunophenotype) with an increased risk for disease progression. These observations support the fact that, although the current consensus diagnostic criteria for systemic mastocytosis have been a major advance for the diagnosis and classification of the disease, rationale usage of the most sensitive diagnostic techniques available nowadays is needed to improve the diagnosis, refine the classification, and reach objective prognostic stratification of adult mastocytosis.

Increased serum baseline tryptase levels and extensive skin involvement are predictors for the severity of mast cell activation episodes in children with mastocytosis.

BACKGROUND: Despite the good prognosis of pediatric mastocytosis, some patients suffer from severe mast cell (MC) mediator-associated symptoms. The aim of this study was to identify predictors for severe MC mediator release symptoms in children with mastocytosis in the skin (MIS). METHODS: Serum baseline total tryptase (sbT) levels in 111 children with MIS - 80 maculopapular cutaneous mastocytosis/plaque mastocytosis, 22 nodular mastocytosis, and nine diffuse cutaneous mastocytosis - were investigated as a predictive biomarker for the occurrence of MC mediator-related signs and symptoms within the first 18 months after disease onset. RESULTS: Twelve children (11%) who showed extensive cutaneous disease involving >90% of body surface area (BSA) suffered from severe symptoms requiring hospitalization, with (n = 5) or without (n = 6) management in the intensive care unit (ICU) owing to life-threatening complications. The median sbT was significantly (P < 0.001) higher in patients with extensive cutaneous disease vs those with <90% of BSA involved (45.5 vs 5.2 µg/l, respectively), as well as in children with grade 4 (severe mastocytosis-related symptoms requiring emergency therapy and hospitalization) vs those with grade <4 (46.2 vs 5.2 µg/l, respectively). Receiver operating characteristics curve analyses showed that the optimal cutoff s for sbT to predict the need for daily antimediator therapy, hospitalization, and the management in an ICU were 6.6, 15.5, and 30.8 µg/l, respectively (sensitivity and specificity of 77% and 79%, 100% and 95%, and 100% and 96%, respectively). CONCLUSIONS: Increased sbT in association with extensive cutaneous involvement identifies patients at risk for severe MC activation events in pediatric mastocytosis.

Validation of the REMA score for predicting mast cell clonality and systemic mastocytosis in patients with systemic mast cell activation symptoms.

BACKGROUND: A variable percentage of patients with systemic mast cell (MC) activation symptoms meet criteria for systemic mastocytosis (SM). We prospectively evaluated the clinical utility of the REMA score versus serum baseline tryptase (sBt) levels for predicting MC clonality and SM in 158 patients with systemic MC activation symptoms in the absence of mastocytosis in the skin (MIS). METHODS: World Health Organization criteria for SM were applied in all cases. MC clonality was defined as the presence of KIT-mutated MC or by a clonal HUMARA test. The REMA score consisted of the assignment of positive or negative points as follows: male (+1), female (-1), sBt <15 µg/l (-1) or >25 µg/l (+2), presence (-2) or absence (+1) of pruritus, hives or angioedema and presence (+3) of presyncope or syncope. Efficiency of the REMA score for predicting MC clonality and SM was assessed by receiver operating characteristic (ROC) curve analyses and compared to those obtained by means of sBt levels alone. RESULTS: Molecular studies revealed the presence of clonal MC in 68/80 SM cases and in 11/78 patients who did not meet the criteria for SM. ROC curve analyses confirmed the greater sensitivity and a similar specificity of the REMA score versus sBt levels (84 vs. 59% and 74 vs. 70% for MC clonality and 87 vs. 62% and 73 vs. 71% for SM, respectively). CONCLUSIONS: Our results confirm the clinical utility of the REMA score to predict MC clonality and SM in patients suffering from systemic MC activation symptoms without MIS.

An immature immunophenotype of bone marrow mast cells predicts for multilineage D816V KIT mutation in systemic mastocytosis.

D816V KIT mutation of bone marrow (BM) mast cells (MC) is a common feature to systemic mastocytosis (SM) patients. Nevertheless, occurrence of the KIT mutation in BM cell compartments other than MC is associated with progression to more aggressive forms of the disease and poor outcome in indolent SM (ISM). Here, we assessed the potential association between the immunophenotype of MC and multilineage KIT mutation in the BM of SM patients through the investigation of the flow cytometric protein expression profile (PEP) of bone marrow mast cells (BMMC) from 70 control individuals and 206 SM patients, classified according to the WHO (World Health Organization), and the degree of involvement of BM hematopoiesis by the D816V KIT mutation; additionally, we developed a score-based class prediction algorithm for the detection of SM cases with multilineage mutation. Our results show that aberrant expression of CD25 with a FcɛRI(lo), FSC(lo), SSC(lo) and CD45(lo) immature phenotype of BMMC, in the absence of coexisting normal MC in the BM, was associated with multilineage involvement by the D816V KIT mutation, regardless of the diagnostic subtype of the disease (for example, indolent vs aggressive SM), which supports the utility of the immunophenotype of BMMC as a surrogate marker to screen for multilineage KIT mutation in ISM.

Evaluation of basophil activation in mastocytosis with Hymenoptera venom anaphylaxis.

BACKGROUND: Basophil activation tests (BATs) have been demonstrated to be useful in detecting IgE-mediated sensitization by measuring basophil activation surface markers (CD63 and CD203c). Hymenoptera venom is one of the best known mediators-release trigger in patients with systemic mastocytosis (SM). The aim of this study was to investigate the use of BATs as an additional diagnostic tool in patients with mastocytosis suffering from hymenoptera venom anaphylaxis (HVA). METHODS: A total of 22 patients with history of HVA and SM, together with a group of 11 patients with HVA in whom SM was ruled out after a complete bone marrow study, were analyzed. RESULTS: Among 11 SM patients who had specific serum IgE (sIgE) against hymenoptera venom and an evaluable BAT, a positive BAT was found in nine. Additionally, a positive BAT was detected in three of seven patients who had no sIgE. These three patients had low levels of total IgE compared with control population (mean of 20 vs. 78 IU/mL); one had discontinued immunotherapy after 5 years, when sIgE levels had turned negative, and, in the other two patients, BAT identified the culprit insect. CONCLUSIONS: BAT is a useful complementary diagnostic tool to sIgE in mastocytosis patients with HVA, and it may contribute to predict or confirm these nearly fatal reactions, especially before discontinuing venom immunotherapy in patients who are negative for skin tests or sIgE or display low total IgE levels; in such cases, it also provides evidence on the culprit insect prompting HVA.

Clinical impact of pregnancy in mastocytosis: a study of the Spanish Network on Mastocytosis (REMA) in 45 cases.

BACKGROUND: The impact of pregnancy on mast cell (MC)-related symptoms and newborn outcome in women with mastocytosis is not well described. We report a series of 30 women who had 45 pregnancies. METHODS: Patients completed a specific questionnaire concerning MC mediator release symptoms graded according to their frequency to detect clinical changes occurring during pregestation and pregnancy as well as postpartum. Information about the medications received during pregnancy and labor and about newborn medical complications was also recorded. RESULTS: Worsening of MC-related symptoms during pregnancy was observed in 10 cases (22%); additionally, 1 woman developed skin lesions as a manifestation of indolent systemic mastocytosis (ISM) within the third trimester of pregnancy. Conversely, 15 cases (33%) experienced clinical improvement during pregnancy, with a complete resolution of pregestational symptoms in 7 cases. MC mediator release symptoms intrapartum were observed in 5 cases (11%) without any fatal outcome. Newborn medical complications (e.g. prematurity, low birth weight, and respiratory distress) were detected in 7 infants (16%) who were all successfully managed with conservative measures. One infant developed cutaneous mastocytosis several years after birth. CONCLUSIONS: Mastocytosis has a heterogeneous clinical behavior during pregnancy: the profile of MC-related symptoms remained unchanged in half of the cases, while in the other half pregnant women experienced either an improvement or an exacerbation of the symptoms, with the manifestation of ISM during pregnancy in 1 case. To prevent potential life-threatening MC-related symptoms, adequate prophylactic antimediator therapy intrapartum should be systematically administered. The absence of both maternal and infant severe complications suggests that patients with nonaggressive categories of mastocytosis should not be advised against pregnancy.

Mastocytosis: oral implications of a rare disease.

Mastocytosis encompasses a group of rare clinical entities, which are characterized by an abnormal growth and, usually, low accumulation of clonal and morphologically abnormal mast cells (MCs), within one or more organs. Clinical presentations are quite variable and symptoms are usually related to the release of mast cell mediators, tissue infiltration by MC (usually in the aggressive categories of the disease), or both. Mast cells are hematopoietic-derived cells that reach phenotypic maturity in the mucosa and peripheral connective tissues. These cells play an active role both on immunologic and non-immunologic processes. Within the oral cavity, MCs reside in the connective tissues, in physiologic conditions, and their number is elevated in pathologic situations resulting from immunoinflammatory processes, such as pulpal inflammation and periodontal disease. As MCs influence so many phenomena within the oral cavity, mastocytosis may manifest itself in the oral tissues. Patients with mastocytosis should be put under special care by dental professionals, in what concerns not only general patient management, but also drug prescription, as they are particularly prone to anaphylaxis and other peri and post-operative complications. Several allergens or mast cell activation triggers such as local anesthetics, zinc oxide, eugenol, penicilins, metals and oral hygiene products are frequently administered or prescribed by dentists. Patients with mastocytosis may also require stress management, during dental consultation. This review aims to briefly summarize the potential ways in which mast cell disease may affect the oral cavity and the dental management of mastocytosis affected patients.

Topical sodium cromoglicate relieves allergen- and histamine-induced dermal pruritus.

BACKGROUND: Sodium cromoglicate (SCG) has long been used in the management of allergic diseases, including as an ointment for atopic dermatitis. Although mast cell stabilization was initially considered as its mechanism of action, anti-inflammatory actions and modulation of sensory nerve function have also been suggested. OBJECTIVES: To investigate the mechanism(s) by which SCG relieves allergen- and histamine-induced dermal inflammation by assessing its effects on pruritus, flare, skin temperature and weal volume. METHODS: Aqueous cream containing 0.2%, 1% or 4% SCG or no SCG (placebo) was applied in a randomized single-blind manner to four areas on each forearm (two sites per arm) and covered with an occlusive dressing. One hour later, skin-prick tests were performed in 20 allergic subjects with allergens to which they had previously shown sensitization, and in 40 nonallergic subjects with codeine (9 mg mL(-1), 20 subjects) and histamine (10 mg mL(-1), 20 subjects). Weal volume, skin temperature increase, erythema area and pruritus intensity were assessed at 0, 5, 10 and 15 min. RESULTS: SCG significantly (P < 0.05 to P < 0.001) reduced pruritus induced by all stimuli, with 4% SCG being most effective. Significant (P < 0.05 to P < 0.01) reductions of erythema area were also seen but there was no inhibition of weal volume or temperature increase. CONCLUSIONS: SCG is effective in reducing pruritus but has no effect on weals, supporting the proposition that, in the skin, SCG inhibits sensory C-fibre nerve activation rather than preventing mast cell degranulation. We suggest that topical SCG treatment, delivered in an appropriate vehicle, may be beneficial for symptomatic relief of pruritus in patients with cutaneous mastocytosis and other pruritic dermatoses.