A Review of the Clinical Features and Management of Systemic Congenital Mastocytosis through the Presentation of An Unusual Prenatal-Onset Case.

Mastocytosis is a heterogeneous group of rare hematological disorders that can occur in infancy. We report a 16-year-old girl who presented with an aggressive form of systemic congenital mastocytosis, associated with a significant global developmental delay, deafness, and multiple anomalies. At 4 years of age, she developed a germinoma presenting as an invasive spinal mass. Extensive cytogenetic, metabolic, and molecular genetic studies that included whole-exome sequencing studies revealed a KIT alteration (NM_000222.3(KIT):c2447A > 7 pAsp816Val) and likely pathogenic variant in the DNA from peripheral blood and skin lesions. C-kit was also found to be overexpressed in the spinal tumor cells. We compared the features of this child to those of six previously reported pediatric patients with cutaneous mastocytosis, microcephaly, microtia, and/or hearing loss reported in OMIM as mastocytosis, conductive hearing loss, and microtia (MIM 248910), for which the etiology has not yet been determined. This report extends the currently recognized spectrum of KIT-related disorders and provides clues as to the potential etiology of a syndromic form of congenital mastocytosis. International efforts to understand the benefits of long-term targeted therapy with tyrosine kinase inhibitors for this KIT-altered rare disease should continue to be evaluated in clinical trials.

A case of cutaneous bullous mastocytosis in a Yorkshire terrier puppy.

BACKGROUND: Cutaneous bullous mastocytosis (CBM) is a rare disease characterised by erythroderma, bullae formation on trunk, scalp and extremities which evolve to erosions. OBJECTIVE: To describe a rare variant of cutaneous mastocytosis and treatment options. ANIMAL: A 7-month-old Yorkshire terrier puppy with erythroderma and bullae formation. METHODS: Clinical examination (including haematological, biochemical and radiographic), skin biopsy, histopathological and immunohistochemical evaluation. CONCLUSION AND CLINICAL RELEVANCE: The case fulfills the criteria of CBM, representing a rare entity that is reported to be associated with spontaneous regression. However, in severe cases treatment with systemic corticosteroids, H1 and H2 antihistamines, and masitinib can be performed.

Contexte - La mastocytose cutanée bulleuse (CBM) est une maladie rare caractérisée par une érythrodermie, la formation de bulles sur le tronc, le cuir chevelu et les extrémités qui évoluent vers des érosions. Objectif - Décrire une variante rare de la mastocytose cutanée et les options de traitement. Animal - Un chiot Yorkshire terrier de 7 mois avec formation d'érythrodermie et de bulles. Méthodes - Examen clinique (y compris hématologique, biochimique et radiographique), biopsie cutanée, évaluation histopathologique et immunohistochimique. Conclusion et pertinence clinique - Le cas remplit les critères de CBM, représentant une entité rare rapportée comme étant associée à une régression spontanée. Cependant, dans les cas graves, un traitement avec des corticostéroïdes systémiques, des antihistaminiques H1 et H2 et du masitinib peut être effectué.

Introducción - la mastocitosis bullosa cutánea (CBM) es una enfermedad rara caracterizada por eritroderma, formación de bullas en el tronco, cabeza y extremidades que evolucionan a erosiones. Objetivo - describir una variante rara de mastocitosis cutánea y opciones de tratamiento. Animal- un cachorro Yorkshire terrier de 7 meses con eritroderma y formación de bullas. Métodos - examen clínico (incluyendo hematológico, bioquímico y radiográfico), biopsia de piel, evaluación histopatológica e inmunohistoquímica. Conclusión y relevancia clínica- el caso descrito cumple con los criterios de CBM, lo que representa una entidad rara que se describe como asociada con regresión espontánea. Sin embargo, en casos graves se puede realizar tratamiento con corticoides sistémicos, antihistamínicos H1 y H2 y masitinib.

Contexto - A mastocitose cutânea bolhosa (MCB) é uma doença rara caracterizada por eritrodermia, formações bolhosas no tronco, cabeça e extremidades que evoluem para erosões. Objetivo - Descrever uma variante rara de mastocitose cutânea e as opções de tratamento. Animal - Um filhote de Yorkshire terrier de sete meses de idade com eritrodermia e formações bolhosas. Métodos - Exame clínico (incluindo avaliação hematológica, bioquímica e radiográfica), biópsia de pele, histopatologia e avaliação imunohistoquímica. Conclusão e relevância clínica - Esse caso preenche os critérios de MCB, representando uma entidade rara em que a regressão espontânea é relatada. Entretanto, em casos graves, tratamento com corticosteroides, anti-histamínicos H1 e H2 e masitinib podem ser realizados.

A case of omalizumab as a successful treatment for telangiectasia macularis eruptiva perstans.

Treatment for telangiectasia macularis eruptiva perstans (TMEP) is often challenging due to lack of an established first-line therapy and as such is primarily focused on symptomatic relief. Omalizumab shows promise as a potential therapy for mast cell disorders; however, its efficacy in TMEP is yet to be established. This case describes a 72-year-old woman with chronic refractory TMEP achieving symptomatic remission within 4 months of commencing omalizumab therapy.

Molecular Background, Clinical Features and Management of Pediatric Mastocytosis: Status 2021.

Pediatric mastocytosis is a heterogeneous disease characterized by accumulation of mast cells in the skin and less frequently in other organs. Somatic or germline mutations in the KIT proto-oncogene are detected in most patients. Cutaneous mastocytosis is the most common form of the disease in children. In the majority of cases, skin lesions regress spontaneously around puberty. However, in few patients, mastocytosis is not a self-limiting disease, but persists into adulthood and can show signs of systemic involvement, especially when skin lesions are small-sized and monomorphic. Children with mastocytosis often suffer from mast cell mediator-related symptoms. Severe hypersensitivity reactions can also occur, mostly in patients with extensive skin lesions and blistering. In a substantial number of these cases, the triggering factor of anaphylaxis remains unidentified. Management of pediatric mastocytosis is mainly based on strict avoidance of triggers, treatment with H1 and H2 histamine receptor blockers, and equipment of patients and their families with epinephrine auto-injectors for use in severe anaphylactic reactions. Advanced systemic mastocytosis occurs occasionally. All children with mastocytosis require follow-up examinations. A bone marrow investigation is performed when advanced systemic mastocytosis is suspected and has an impact on therapy or when cutaneous disease persists into adulthood.

Risk and management of patients with mastocytosis and MCAS in the SARS-CoV-2 (COVID-19) pandemic: Expert opinions.

The coronavirus disease 2019 (COVID-19) (caused by severe acute respiratory syndrome coronavirus 2) pandemic has massively distorted our health care systems and caused catastrophic consequences in our affected communities. The number of victims continues to increase, and patients at risk can only be protected to a degree, because the virulent state may be asymptomatic. Risk factors concerning COVID-19-induced morbidity and mortality include advanced age, an impaired immune system, cardiovascular or pulmonary diseases, obesity, diabetes mellitus, and cancer treated with chemotherapy. Here, we discuss the risk and impact of COVID-19 in patients with mastocytosis and mast cell activation syndromes. Because no published data are yet available, expert opinions are, by necessity, based on case experience and reports from patients. Although the overall risk to acquire the severe acute respiratory syndrome coronavirus 2 may not be elevated in mast cell disease, certain conditions may increase the risk of infected patients to develop severe COVID-19. These factors include certain comorbidities, mast cell activation-related events affecting the cardiovascular or bronchopulmonary system, and chemotherapy or immunosuppressive drugs. Therefore, such treatments should be carefully evaluated on a case-by-case basis during a COVID-19 infection. In contrast, other therapies, such as anti-mediator-type drugs, venom immunotherapy, or vitamin D, should be continued. Overall, patients with mast cell disorders should follow the general and local guidelines in the COVID-19 pandemic and advice from their medical provider.

The secondary KIT mutation p.Ala510Val in a cutaneous mast cell tumour carrying the activating mutation p.Asn508Ile confers resistance to masitinib in dogs.

BACKGROUND: Gain-of-function mutations in KIT are driver events of oncogenesis in mast cell tumours (MCTs) affecting companion animals. Somatic mutations of KIT determine the constitutive activation of the tyrosine kinase receptor leading to a worse prognosis and a shorter survival time than MCTs harbouring wild-type KIT. However, canine MCTs carrying KIT somatic mutations generally respond well to tyrosine kinase inhibitors; hence their presence represents a predictor of treatment effectiveness, and its detection allows implementing a stratified medical approach. Despite this, veterinary oncologists experience treatment failures, even with targeted therapies whose cause cannot be elucidated. The first case of an MCT-affected dog caused by a secondary mutation in the tyrosine kinase domain responsible for resistance has recently been reported. The knowledge of this and all the other mutations responsible for resistance would allow the effective bedside implementation of a deeply stratified and more effective medical approach. CASE PRESENTATION: The second case of a canine MCT carrying a different resistance mutation is herein described. The case was characterised by aggressive behaviour and early metastasis unresponsive to both vinblastine- and masitinib-based treatments. Molecular profiling of the tumoural masses revealed two different mutations; other than the already known activating mutation p.Asn508Ile in KIT exon 9, which is tyrosine kinase inhibitor-sensitive, a nearly adjacent secondary missense mutation, p.Ala510Val, which had never before been described, was detected. In vitro transfection experiments showed that the secondary mutation did not cause the constitutive activation by itself but played a role in conferring resistance to masitinib. CONCLUSIONS: This study highlighted the importance of the accurate molecular profiling of an MCT in order to improve understanding of the molecular mechanism underlying tumourigenesis and reveal chemoresistance in MCTs for more effective therapies. The detection of the somatic mutations responsible for resistance should be included in the molecular screening of MCTs, and a systematic analysis of all the cases characterised by unexpected refractoriness to therapies should be investigated in depth at both the genetic and the phenotypic level.

The efficacy of omalizumab in Cutaneous Mastocytosis: A case series.

BACKGROUND: Mastocytosis describes a heterogeneous group of disorders arising from a clonal proliferation of mast cells. Given the lack of curative treatments for the cutaneous form, there is a significant need for superior therapies. Omalizumab is a recombinant DNA-derived humanized IgG monoclonal antibody that selectively binds to human immunoglobulin E (IgE). It represents a potential treatment for the management of cutaneous mastocytosis, which currently has no standard treatment. METHODS: Two patients were treated with subcutaneous omalizumab 300 mg every 4 weeks. DISCUSSION: Patient 1 experienced 50% reduction in cutaneous infiltration and moderate improvement in pruritus. Patient 2 underwent 90% complete clearance of cutaneous lesions and reported full resolution of pruritus. The median duration of treatment was 24 weeks and time to response was 8 weeks. No significant changes in tryptase levels were observed. Both patients experienced injection site reactions. CONCLUSION: We provide evidence from two cases supporting the efficacy of IgE-mediated therapy in the treatment of cutaneous mastocytosis. Even at a higher-than-standard dose (300 mg vs. 150 mg), the drug was well-tolerated. As we await the results of pivotal clinical trials, omalizumab appears to be a promising treatment option in patients with cutaneous mastocytosis unresponsive to traditional therapies.

Lokivetmab therapy for pruritus in a dog with cutaneous mastocytosis.

BACKGROUND: Cutaneous mastocytosis (CM) is a rare disease of dogs characterized by rash, pruritus and proliferation of mast cells in the skin. Oral H1 antihistamines are recommended as the treatment to control pruritus. HYPOTHESIS/OBJECTIVE: To describe the effective treatment of pruritus associated with CM with lokivetmab in one dog. ANIMAL: A 4-year-old, spayed female cross-bred dog presented with severely pruritic, erythematous to pigmented macules and papules involving the ventral abdomen, interdigital skin, perivulval area and both pinnae; the pruritus had been unresponsive to treatment with antihistamines, prednisone and ciclosporin. METHODS AND MATERIALS: Complete blood count and serum biochemistry, abdominal ultrasound, blood smear and skin cytological evaluation, PCR, histopathological and immunohistochemical examination of skin biopsies. RESULTS: Skin cytological evaluation revealed high numbers of uniform, heavily granulated mast cells; histopathological findings showed focal dermal proliferations of well-differentiated, uniform mast cells consistent with a low-grade mast cell tumour (MCT). Clinical staging revealed that the disease was confined to the skin. Mutations of c-kit exon 8 and 11 were not detected. Treatment was initiated with anti-canine-interleukin (IL)-31 monoclonal antibody lokivetmab; antihistamines were continued. The dog's pruritus resolved within seven days and was maintained in remission over 15 months with once monthly lokivetmab injections; the skin lesions improved but did not resolve. CONCLUSION AND CLINICAL IMPORTANCE: Lokivetmab treatment was effective in resolving and maintaining pruritus remission in this dog with widespread cutaneous mast cell disease. Whether CM in dogs represent a separate entity that should be distinguished from a low-grade MCT requires further investigation.

Kit Mutations: New Insights and Diagnostic Value.

Mastocytosis is a World Health Organization-defined clonal mast cell disorder characterized by significant clinicopathologic heterogeneity. Despite this diversity, a mutation of the KIT gene, most commonly D816V, is found in almost all cases and believed a driver lesion. Peripheral blood allele-specific oligonucleotide polymerase chain reaction can reliably detect KIT D816V and is used for the initial screening of adults with suspected systemic mastocytosis. The discovery of KIT mutations as central to the pathobiology of mastocytosis has prompted development of KIT-targeted agents, including imatinib and midostaurin (approved medications for patients with advanced systemic mastocytosis), and drugs in development, like KIT D816V-specific inhibitor avapritinib.

Effective management of severe cutaneous mastocytosis in young children with omalizumab (Xolair® ).

Omalizumab (Xolair® ) is an anti-IgE monoclonal antibody, which may benefit adults with systemic mastocytosis. We report effective treatment with omalizumab in two toddlers with severe diffuse cutaneous mastocytosis. Our cases offer preliminary evidence to support the safe use of omalizumab in paediatric patients with cutaneous mastocytosis.

Well-Appearing Newborn With a Vesiculobullous Rash at Birth.

A term, appropriate-for-gestational-age, male infant born via normal spontaneous vaginal delivery presented at birth with a full-body erythematous, vesiculobullous rash. He was well-appearing with normal vital signs and hypoglycemia that quickly resolved. His father had a history of herpes labialis. His mother had an episode of herpes zoster during pregnancy and a prolonged rupture of membranes that was adequately treated. The patient underwent a sepsis workup, including 2 attempted but unsuccessful lumbar punctures, and was started on broad-spectrum antibiotics and acyclovir, given concerns about bacterial or viral infection. The rash evolved over the course of several days. Subsequent workup, with particular attention to his history and presentation, led to his diagnosis.