Mastocytosis. Curr Opin Allergy Clin Immunol. 2001;1:449-454. [PMID: 11964726 DOI: 10.1097/00130832-200110000-00011]

Death from mast cell leukemia: a young patient with longstanding cutaneous mastocytosis evolving into fatal mast cell leukemia

   Mastocytosis is a broad term used for a group of disorders characterized by accumulation of mast cells in the skin with or without extracutaneous involvement. The clinical spectrum of the disease varies from only cutaneous lesions to highly aggressive systemic involvement such as mast cell leukemia. Mastocytosis can present from birth to adulthood. In children, mastocytosis is usually benign, and there is a good chance of spontaneous regression at puberty, unlike adult-onset disease, which is generally systemic and more severe. Moreover, individuals with systemic mastocytosis may be at risk of developing hematologic malignancies. We describe a girl who presented to us with a solitary mastocytoma at age 5 and later developed maculopapular cutaneous mastocytosis. At age 23, after an episode of anaphylactic shock, a bone marrow examination revealed mast cell leukemia. She ultimately died despite aggressive chemotherapy and bone marrow transplantation.

Pathogenesis, classification and treatment of mastocytosis: state of the art in 2010 and future perspectives

Mastocytosis is a myeloid neoplasm characterized by abnormal accumulation and frequent activation of mast cells (MCs) in various organs. Organ systems typically involved are the bone marrow, skin, liver and gastrointestinal tract. In most adult patients, the systemic form of mastocytosis (SM) is diagnosed, which includes an indolent subvariant, an aggressive subvariant and a leukemic subvariant, also termed MC leukemia. Whereas in pediatric mastocytosis, which is usually confined to the skin, a number of different KIT mutations and other defects may be detected, the KIT mutation D816V is detectable in most (adult) patients with SM. In a subset of these patients, additional oncogenic factors may lead to enhanced survival and growth of MCs and, thus, to advanced SM. Other factors may lead to MC activation, with consecutive anaphylactic reactions that can be severe or even fatal. Treatment of SM usually focuses on symptom relief by histamine receptor antagonists and other supportive therapy. However, in aggressive and leukemic variants, cytoreductive and targeted drugs must be applied. Unfortunately, the prognosis in these patients remains poor, even when treated with novel KIT-targeting agents, polychemotherapy or stem cell transplantation. This article provides a summary of our knowledge on the pathogenesis and on treatment options in SM.

Ionizing radiation induces degranulation of human mast cells and release of tryptase

PURPOSE

Skin fibrosis is a hallmark of ionizing radiation-induced tissue injury and we hypothesized that mast cells via their products (especially tryptase) are involved in this event. We therefore investigated whether: (i) irradiation with 5 Gray (Gy) is able to induce the release of the typical mast cell mediator tryptase from human mast cells (HMC-1) in vitro, (ii) this effect can be influenced by application of clinically relevant mast cell blockers, and (iii) irradiation leads to mast cell degranulation in ex vivo skin culture models.

MATERIALS AND METHODS

The human mast cell line (HMC)-1, as well as ex vivo skin tissue served as experimental models. Fluorescence activated cell sorting (FACS), Enzyme linked immunosorbent assays (ELISA), mast cell degranulation assays and immunohistochemistry were applied.

RESULTS

Ionizing radiation induces a time-dependent, statistically significant increase in the release of tryptase by HMC-1 cultured in vitro. Mast cell degranulation and secretion of tryptase was partially, but not significantly, inhibited by pre-incubation with the histamine-1 receptor (H1) blocker cetirizine. Mast cell degranulation was also clearly evident after irradiation using an ex vivo skin culture model of mastocytoma tissue.

CONCLUSIONS

We propose that ionizing radiation leads to a degranulation of dermal mast cells, an event which is accompanied by the release of tryptase.

Tumoral mast cells exhibit a common spatial distribution

Mast cells (MCs) accumulate in the stroma surrounding tumors and take part in the inflammatory reaction occurring at the margin of the neoplasia. Moreover, MC secretes angiogenic cytokines and matrix metalloproteinases. The aim of this study was to investigate the pattern of distribution of MCs in biopsy samples obtained from four different human tumors, utilizing an image analysis system and a mathematical model to make a quantitative approach to characterizing their spatial distribution. Results showed a similar spatial arrangement of MCs in all the neoplastic tissues examined, despite histological and/or pathologic differences. In all these tissues MCs demonstrated a virtually random spatial distribution, albeit with varying densities. These results suggest that MC-MC interactions could play a minor role in the formation of the MC pattern in neoplastic tissues. The random distribution of the cells in the tissues could be accounted for by a random walk-migration under the influence of cell-matrix interactions or chemotactic fields potentially generated by tumor or endothelial cells.

Anaphylaxis in patients with mastocytosis: a study on history, clinical features and risk factors in 120 patients

BACKGROUND

Excessive mast cell mediator release may lead to anaphylaxis in patients with mastocytosis. However, the incidence, clinical features and trigger factors have not yet been analyzed.

METHODS

To identify risk factors for anaphylaxis in mastocytosis, we determined cumulative incidence, severity, clinical characteristics, and trigger factors for anaphylaxis in 120 consecutive patients (53 male; 67 female, median age and range 24 years, 1 month to 73 years), and correlated these with disease severity of mastocytosis, skin involvement, basal total serum tryptase, and diaminooxidase concentrations.

RESULTS

The cumulative incidence of anaphylaxis in patients with mastocytosis was higher in adults (49%; P < 0.01) compared with that in children (9%). Only children with extensive skin involvement had experienced anaphylaxis. In adults, anaphylaxis was correlated to the absence of urticaria pigmentosa lesions (P < 0.03). Reactions occurred more frequently in adults with systemic (56%) when compared with cutaneous mastocytosis (13%; P < 0.02). In adults, 48% of reactions were severe, and 38% resulted in unconsciousness. Major perceived trigger factors for adults were hymenoptera stings (19%), foods (16%), and medication (9%); however, in 26% of reactions, only a combination of different triggers preceded anaphylaxis. Trigger factors remained unidentified in 67% of reactions in children compared with 13% in adults. Patients with anaphylaxis had higher basal tryptase values (60.2 +/- 55 ng/ml, P < 0.0001) in comparison with those without (21.2 +/- 33 ng/ml), but not diaminooxidase levels.

CONCLUSION

Adult patients and children with extensive skin disease with mastocytosis have an increased risk to develop severe anaphylaxis; thus, an emergency set of medication including epinephrine is recommended.

Tryptase detection in bone-marrow blood: a new diagnostic tool in systemic mastocytosis

BACKGROUND

The condition mastocytosis includes a heterogenous group of disorders that are characterized by abnormal growth and accumulation of mast cells. The detection of serum tryptase, an essential mast cell enzyme, is a widely used tool in the diagnosis of mastocytosis. The diagnosis of systemic mastocytosis is substantially based on the histologic examination of bone-marrow biopsy specimens.

OBJECTIVE

We hypothesized that the detection of tryptase in bone-marrow blood might provide additional, more sensitive information on the bone-marrow involvement of patients with mastocytosis.

METHODS

Serum tryptase was monitored in patients with cutaneous symptoms (n = 17), patients with extracutaneous symptoms (n = 16), and healthy control subjects (n = 359). Bone-marrow biopsy specimens of patients with systemic mastocytosis (n = 7) and control subjects (n = 7) were investigated histologically and bone-marrow blood of these individuals was analyzed on the tryptase levels.

RESULTS

We could detect for the first time significantly elevated tryptase levels in bone-marrow blood of patients with systemic mastocytosis. Secondarily we could present a clear correlation between the level of serum tryptase and the clinical symptoms of mastocytosis.

LIMITATIONS

With the present study, we establish a new diagnostic tool for systemic mastocytosis. Unfortunately, we can only present a limited number of cases, since systemic mastocytosis is a rare disease involving few patients.

CONCLUSION

Our results indicate that the measurement of tryptase in bone-marrow blood is a new, sensitive marker of the mast cell burden in bone marrow of patients with systemic mastocytosis.

Urticária pigmentosa em adulto com apresentação clínica exuberante

A mastocitose é afecção rara e heterogênea, caracterizada por aumento da densidade dos mastócitos na pele e em outros órgãos, para a qual não há tratamento específico. Descreve-se um caso de urticária pigmentosa em paciente adulta com quadro clínico exuberante.

A novel gain of function mutant in C-kit gene and its tumorigenesis in nude mice

AIM

To transfect mutant C-kit cDNA at codon 579 into human embryonic kidney cell line to observe its role in the pathogenesis of gastrointestinal stromal tumor (GIST).

METHODS

Eukaryotic expression vectors of pcDNA3-Kit-NW and pcDNA3-Kit-W were constructed. Then pcDNA3-Kit-NW and pcDNA3-Kit-W plasmids were transfected into human embryonic kidney cell line by Lipofectamine. The resistant clone was screened by G418 filtration and identified by sequencing, Western blotting, and immunocytochemical staining. Human embryonic kidney cells were divided into three groups including pcDNA3-Kit-NW, pcDNA3-Kit-W, and vector control groups. Absorbency value with a wavelength of 574 nm was detected by MTT analysis. Mice were injected with three groups of cells. Volume, mass, and histological examinations of the tumors in different groups were measured and compared.

RESULTS

The C-kit gene and mutant C-kit gene were successfully cloned into the eukaryotic expression vector pcDNA3. pcDNA3-Kit-NW and pcDNA3-Kit-W were successfully transfected into human embryonic kidney cell line and showed stable expression in this cell line. Cell proliferating activity had significant differences between pcDNA3-Kit-NW and pcDNA3, pcDNA3-Kit-NW and pcDNA3-Kit-W (P<0.05), respectively. Tumors were only observed in nude mice implanted with cells transfected with pcDNA3-Kit-NW.

CONCLUSION

Mutation of C-kit gene increases the proliferation activity of human cells and plays an important role in the malignant transformation of GIST.

Urticaria and angioedema

Urticaria and angioedema are commonly encountered complaints in children. Although the diagnosis is clear, establishing an etiology, especially with respect to chronic urticaria, can be challenging. A significant proportion of chronic urticarial cases are now considered to have an autoimmune etiology. This article reviews progress in the field of urticaria and angioedema including developments in pathogenesis, description of laboratory testing, and review of medications. Urticaria and angioedema can usually be controlled by avoidance of triggers, a variety of supportive medications, and reassurance.

Transcriptional regulation of SLP-76 family hematopoietic cell adaptor MIST/Clnk by STAT5

SLP-76-related adaptor protein MIST (also called Clnk) is expressed in a variety of cytokine-dependent hematopoietic cell lines of myeloid and lymphoid origin as well as some cytokine-independent mast cell lines. To understand the molecular mechanisms underlying the MIST gene expression, we have characterized the 5'-flanking region of the mouse MIST gene. We have identified an enhancer region (-773 to -709), which is active in P815 mast cells expressing the endogenous MIST gene, but not in EL-4 T cells lacking MIST expression. Outside of this enhancer region, one STAT element present in the MIST promoter (-44 to -36) was found to bind STAT5A when IC-2 mast cells were stimulated with IL-3. Mutation of this STAT element did not affect basal MIST promoter activity in P815 mast cells, but was required for STAT5-mediated activation of the MIST promoter. Furthermore, endogenous MIST gene expression was induced in mast cells by a constitutively activated form of STAT5A, but not by an active mutant of c-Kit receptor. These findings suggest that STAT5 is involved in cytokine-mediated up-regulation of MIST gene expression, probably in collaboration with other lineage-specific transcription factors that promote basal MIST expression in mast cells.

Urticaria pigmentosa

Urticaria pigmentosa (UP), resulting from the accumulation of excessive numbers of mast cells in the skin, is the most common form of cutaneous mastocytosis. Observations highlight the diversity of this disease. Clonal expansion of early hematopoietic progenitor cells carrying activating mutations in KIT seems to be the basis of adult-onset UP. New pathogenetic findings are leading to the development of new diagnostic surrogate markers of disease and therapeutic approaches targeting neoplastic mast cells. Promising strategies may arise from an increased understanding about the cause of mastocytosis and the signaling pathways initiated by kit activation.

Gastrointestinal stromal tumors in a mouse model by targeted mutation of the Kit receptor tyrosine kinase

Oncogenic Kit mutations are found in somatic gastrointestinal (GI) stromal tumors (GISTs) and mastocytosis. A mouse model for the study of constitutive activation of Kit in oncogenesis has been produced by a knock-in strategy introducing a Kit exon 11-activating mutation into the mouse genome based on a mutation found in a case of human familial GIST syndrome. Heterozygous mutant KitV558Delta/+ mice develop symptoms of disease and eventually die from pathology in the GI tract. Patchy hyperplasia of Kit-positive cells is evident within the myenteric plexus of the entire GI tract. Neoplastic lesions indistinguishable from human GISTs were observed in the cecum of the mutant mice with high penetrance. In addition, mast cell numbers in the dorsal skin were increased. Therefore KitV558Delta/+ mice reproduce human familial GISTs, and they may be used as a model for the study of the role and mechanisms of Kit in neoplasia. Importantly, these results demonstrate that constitutive Kit signaling is critical and sufficient for induction of GIST and hyperplasia of interstitial cells of Cajal.