Mastocytosis and related disorders

Genetic Changes in Mastocytes and Their Significance in Mast Cell Tumor Prognosis and Treatment

Mast cell tumors are a large group of diseases occurring in dogs, cats, mice, as well as in humans. Systemic mastocytosis (SM) is a disease involving the accumulation of mast cells in organs. KIT gene mutations are very often seen in abnormal mast cells. In SM, high KIT/CD117 expression is observed; however, there are usually no KIT gene mutations present. Mastocytoma (MCT)-a form of cutaneous neoplasm-is common in animals but quite rare in humans. KIT/CD117 receptor mutations were studied as the typical changes for human mastocytosis. In 80% of human cases, the KIT gene substitution p.D816H was present. In about 25% of MCTs, metastasis was observed. Changes in the gene expression of certain genes, such as overexpression of the DNAJ3A3 gene, promote metastasis. In contrast, the SNORD93 gene blocks the expression of metastasis genes. The panel of miR-21-5p, miR-379, and miR-885 has a good efficiency in discriminating healthy and MCT-affected dogs, as well as MCT-affected dogs with and without nodal metastasis. Further studies on the pathobiology of mast cells can lead to clinical improvements, such as better MCT diagnosis and treatment. Our paper reviews studies on the topic of mast cells, which have been carried out over the past few years.

Systemic mastocytosis: The roles of histamine and its receptors in the central nervous system disorders

Mastocytosis is a rare disease of clonal hematological disorders characterized by a pathological accumulation of Mast Cells (MCs) in different tissues, with variable symptomatology and prognosis. Signs and symptoms of Systemic Mastocytosis (SM) are due to pathological infiltration of MCs and to the release of chemical mediators, mainly histamine. Patients with SM may also present with neurological symptoms or complications. The pathophysiology of these neurological disorders remains uncertain to this day, but it can be associated with the infiltration of tissue mastocytes, release of mastocytes' mediators or both. Moreover, there is a lot to understand about the role of neurological symptoms in SM and knowing, for example, what is the real frequency of neurological disorders in SM and if is present a relation between other SM subtypes, because it has been noted that the alteration of the histamine expression may be an initiating factor for susceptibility, gravity and progression of the epigenetic disease. In this review we explain the possible pathophysiological mechanism about neurological symptomatology found in some patients affected by SM, describing the role of histamine and its receptors in the nervous system and, in light of the results, what the future prospects may be for a more specific course of treatment.

New Biomarkers of Hymenoptera Venom Allergy in a Group of Inflammation Factors

Hymenoptera venom allergy significantly affects the quality of life. Due to the divergences in the results of the available test and clinical symptoms of patients, the current widely applied diagnostic methods are often insufficient to classify patients for venom immunotherapy (VIT). Therefore it is still needed to search for new, more precise, and accurate diagnostic methods. Hence, this research aimed to discover new biomarkers of Hymenoptera venom allergy in a group of inflammation factors using set of multi-marker Bioplex panel. The adoption of a novel methodology based on Luminex/xMAP enabled simultaneous determination of serum levels of 37 different inflammatory proteins in one experiment. The study involved 21 patients allergic to wasp and/or honey bee venom and 42 healthy participants. According to univariate and multivariate statistics, soluble CD30/tumor necrosis factor receptor superfamily, member 8 (sCD30/TNFRSF8), and the soluble tumor necrosis factor receptor 1 (sTNF-R1) may be considered as effective prognostic factors, their circulating levels were significantly decreased in the allergy group (p-value < 0.05; the Area Under the Curve (AUC) ~0.7; Variable Importance in Projection (VIP) scores >1.2). The obtained results shed new light on the allergic inflammatory response and may contribute to modification and improvement of the diagnostic and monitoring methods. Further, large-scale studies are still needed to explain mechanisms of action of studied compounds and to definitively prove their usefulness in clinical practice.

Acute aleukemic mast cell leukemia: Report of a case and review of the literature

Mast Cell Leukemia (MCL) is the rarest form of systemic mastocytosis, a rare group of neoplastic disease that result from clonal proliferation of mast cells and their accumulation in one or more organ systems. The diagnosis of MCL is made by meeting the World Health Organization (WHO) 2017 criteria. MCL is further subclassified as leukemic or aleukemic based on presence or absence of circulating mast cells in the peripheral blood and acute versus chronic based on presence or absence of findings indicative of impaired organ function due to mast cell infiltration. A 64-year-old Hispanic male presented with myalgia, diarrhea, urticarial rash, back pain, and fulminant disseminated intravascular coagulation. Bone marrow examination, supplemented by immunohistochemistry results, fulfilled the WHO criteria for the diagnosis of MCL. To the best of our knowledge, this is the first documented case of aleukemic acute MCL in a Hispanic patient.

Mast cell tryptase - Marker and maker of cardiovascular diseases

Mast cells are tissue-resident cells, which have been proposed to participate in various inflammatory diseases, among them the cardiovascular diseases (CVDs). For mast cells to be able to contribute to an inflammatory process, they need to be activated to exocytose their cytoplasmic secretory granules. The granules contain a vast array of highly bioactive effector molecules, the neutral protease tryptase being the most abundant protein among them. The released tryptase may act locally in the inflamed cardiac or vascular tissue, so contributing directly to the pathogenesis of CVDs. Moreover, a fraction of the released tryptase reaches the systemic circulation, thereby serving as a biomarker of mast cell activation. Actually, increased levels of circulating tryptase have been found to associate with CVDs. Here we review the biological relevance of the circulating tryptase as a biomarker of mast cell activity in CVDs, with special emphasis on the relationship between activation of mast cells in their tissue microenvironments and the pathophysiological pathways of CVDs. Based on the available in vitro and in vivo studies, we highlight the potential molecular mechanisms by which tryptase may contribute to the pathogenesis of CVDs. Finally, the synthetic and natural inhibitors of tryptase are reviewed for their potential utility as therapeutic agents in CVDs.

Prevalence of CD30 immunostaining in neoplastic mast cells: A retrospective immunohistochemical study

Mastocytosis is a rare disease characterized by clonal neoplastic proliferation of mast cells (MCs). It ranges from skin lesions as cutaneous mastocytosis (CM) which may spontaneously regress to highly aggressive neoplasms with multiorgan involvement corresponding to some aggressive systemic mastocytosis (ASM), mast cell leukemia (MCL), and/or mast cell sarcoma (MCS).There is increasing evidence of CD30 expression in neoplastic MCs of the bone marrow. This expression has been described almost exclusively in aggressive forms of systemic mastocytosis (SM).The aim of the present study is to evaluate CD30 expression both in cutaneous and systemic forms of mastocytosis. Forty-two mastocytosis cases were reviewed, including cutaneous (n = 29) and systemic (n = 13) forms to assess the prevalence of CD30 expression. Thirty-nine out of 42 (92.8%) cases were CD30 positive. In cases of CM, 28/29 (96.5%) cases were CD30 positive, 11/13 cases of SM (84.6%) were positive for CD30. MCs in normal skin biopsies and in urticaria lesions were CD30-negative. This study found that CD30 is also frequently expressed in CM as well as in systemic forms. This finding is a major departure from the prevailing concept that CD30 expression is often related to aggressive systemic forms of mastocytosis.

Solitary mastocytoma in the eyelid of an adult

Purpose

To describe the ophthalmic symptoms and histopathological findings in a rare case of an eyelid mastocytoma in an adult.

Observations

A man in his early 60s developed a painless, non-tender, non-pruritic, mobile nodule on the right lower eyelid beneath the inferior orbital rim. The lesion grew to 15 × 9 mm over eleven months. Biopsy revealed a diffuse infiltrate of histiocytoid and spindle-shaped mast cells forming cords and small nests between collagen fibers in the superficial and deep dermis. Mast cell lineage was confirmed by immunohistochemistry. Physical examination revealed no other cutaneous lesions and no evidence of systemic disease. Serum tryptase level was normal. Annual full-body examination by a dermatologist for 4.5 years has revealed neither recurrence in the eyelid nor cutaneous involvement at other sites.

Conclusions and importance

Mast cell tumors limited to the human eyelid are extremely uncommon with only four previously reported cases, including one in an adult. This case highlights the rare possibility of a solitary mastocytoma presenting in the eyelid of an adult.

Identification of the Ki-1 antigen (CD30) as a novel therapeutic target in systemic mastocytosis

The Ki-1 antigen (CD30) is an established therapeutic target in patients with Hodgkin lymphoma and anaplastic large-cell lymphoma. We have recently shown that CD30 is expressed abundantly in the cytoplasm of neoplastic mast cells (MCs) in patients with advanced systemic mastocytosis (SM). In the current study, we asked whether CD30 is expressed on the surface of neoplastic MCs in advanced SM, and whether this surface structure may serve as therapeutic target in SM. As assessed by flow cytometry, CD30 was found to be expressed on the surface of neoplastic MCs in 3 of 25 patients (12%) with indolent SM, 4 of 7 patients (57%) with aggressive SM, and 4 of 7 patients (57%) with MC leukemia. The immature RAS-transformed human MC line MCPV-1.1 also expressed cell surface CD30, whereas the KIT-transformed MC line HMC-1.2 expressed no detectable CD30. The CD30-targeting antibody-conjugate brentuximab-vedotin inhibited proliferation in neoplastic MCs, with lower IC50 values obtained in CD30(+) MCPV-1.1 cells (10 µg/mL) compared with CD30(-) HMC-1.2 cells (>50 µg/mL). In addition, brentuximab-vedotin suppressed the engraftment of MCPV-1.1 cells in NSG mice. Moreover, brentuximab-vedotin produced apoptosis in all CD30(+) MC lines tested as well as in primary neoplastic MCs in patients with CD30(+) SM, but did not induce apoptosis in neoplastic MCs in patients with CD30(-) SM. Furthermore, brentuximab-vedotin was found to downregulate anti-IgE-induced histamine release in CD30(+) MCs. Finally, brentuximab-vedotin and the KIT D816V-targeting drug PKC412 produced synergistic growth-inhibitory effects in MCPV-1.1 cells. Together, CD30 is a promising new drug target for patients with CD30(+) advanced SM.

Immunohistochemistry in dermatopathology

CONTEXT

Immunohistochemistry is not a diagnostic test but a highly valuable tool that requires interpretation within a context.

OBJECTIVE

To review the current status and limitations of immunohistochemistry in dermatopathology.

DATA SOURCES

English-language literature published between 1980 and 2014.

CONCLUSIONS

Although immunohistochemistry is rarely completely specific or sensitive, it is an important adjunctive technique in dermatopathology and can be helpful in a series of diagnostic dilemmas.

Mast cell function: a new vision of an old cell

Since first described by Paul Ehrlich in 1878, mast cells have been mostly viewed as effectors of allergy. It has been only in the past two decades that mast cells have gained recognition for their involvement in other physiological and pathological processes. Mast cells have a widespread distribution and are found predominantly at the interface between the host and the external environment. Mast cell maturation, phenotype and function are a direct consequence of the local microenvironment and have a marked influence on their ability to specifically recognize and respond to various stimuli through the release of an array of biologically active mediators. These features enable mast cells to act as both first responders in harmful situations as well as to respond to changes in their environment by communicating with a variety of other cells implicated in physiological and immunological responses. Therefore, the critical role of mast cells in both innate and adaptive immunity, including immune tolerance, has gained increased prominence. Conversely, mast cell dysfunction has pointed to these cells as the main offenders in several chronic allergic/inflammatory disorders, cancer and autoimmune diseases. This review summarizes the current knowledge of mast cell function in both normal and pathological conditions with regards to their regulation, phenotype and role.

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.

Red face revisited: Flushing

The term red face is reserved for lesions located exclusively or very predominantly on the face that result from changes in cutaneous blood flow triggered by multiple different conditions. Facial erythema may not only present clinically as a distinct entity, but can also be a sign of other diseases. Patients with a red face challenge clinicians to consider a broad differential diagnosis. Diagnosis is based on date and mode of appearance, characteristics of the erythema, functional signs, and associated systemic manifestations. In most cases, the cause is a benign disease such as rosacea, contact dermatitis, photodermatosis, and climacterium, and a thorough history and physical examination is enough to make a diagnosis; facial erythema may also present as a symptom of drug allergies, cardiac disease, carcinoid syndrome, pheochromocytoma, mastocytosis, and anaphylaxis, as well as some rare causes such as medullary carcinoma of the thyroid, pancreatic cell tumor, and renal carcinoma where further laboratory, radiologic, or histopathologic studies are required. In this review, the mechanisms of flushing, its clinical differential diagnosis, and management of various conditions that cause flushing are discussed.