A comparison of mast cells in skin biopsies of cutaneous mastocytosis with other inflammatory dermatoses: A study of 33 cases.

BACKGROUND: Histopathologic criteria for diagnosis of cutaneous mastocytosis include 20 mast cells per high-power field or clusters of 15 mast cells. We aimed to determine the specificity of these criteria for cutaneous mastocytosis in comparison with inflammatory disorders of mast cell activation. METHODS: Twenty-six cases of spongiotic dermatitis or urticaria were identified from 2021 to 2022. Recuts were stained with mast cell tryptase and slides were reviewed for the presence of 20 mast cells per high-power field and for clusters of 15 mast cells. In addition, seven cases of mastocytosis were reviewed for the same criteria. RESULTS: Twelve of 26 cases (46.1%) of spongiotic dermatitis/urticaria had at least 20 mast cells per high-power field. Three of 26 cases (11.5%) of spongiotic dermatitis/urticaria had a cluster of 15 mast cells. Six of seven cases (85.7%) of mastocytosis had at least 20 mast cells per high-power field; four of seven cases (57.1%) of mastocytosis had a cluster of 15 mast cells. CONCLUSIONS: In our study, the finding of 20 mast cells per high-power field was nonspecific as a single criterion for cutaneous mastocytosis. The finding of clusters of 15 mast cells was more specific but not sensitive.

Characteristics of an ethnically diverse cohort of children with pediatric cutaneous mastocytosis: One institution's experience.

There has been limited research exploring how the demographic characteristics of children with pediatric cutaneous mastocytosis (PCM) may influence both the cutaneous and systemic symptoms. In this observational retrospective study of 51 children with PCM, we found a significantly higher rate of gastrointestinal (GI) symptoms in children of Hispanic ethnicity (4/21,19%) compared to non-Hispanics (0/30, 0%, p = 0.024). While this finding may reflect the high proportion of Hispanics in our population, a racial predisposition toward distinct systemic symptoms may be possible. We also found a significantly lower proportion of Hispanic children being diagnosed with PCM under the age of 3 years (47.6%) when compared with non-Hispanic children (76.7%, p = 0.03), suggesting that more data are needed to further assess the role of ethnicity and healthcare disparities in PCM diagnosis. Larger prospective studies are necessary to better evaluate the association between ethnicity, early diagnosis, and systemic symptoms in PCM and to describe its impact on long-term outcomes.

Idiopathic eruptive macular pigmentation in a pediatric patient and a review of the literature.

Idiopathic eruptive macular pigmentation (IEMP) is a rare, benign, self-resolving melanosis consisting of hyperpigmented macules typically on the face, trunk, and extremities that can occur in children and adolescents and often presents a diagnostic conundrum. We report a case involving an 8-year-old female whose previous clinical presentation was concerning for an atypical presentation of cutaneous mastocytosis or neurofibromatosis. The clinical and histopathologic evaluation was consistent with the diagnosis of IEMP, and no active intervention was pursued. Our accompanying literature review serves to better characterize this condition, highlight key diagnostic features, and emphasize the tendency for spontaneous resolution to avoid unnecessary treatments with limited clinical efficacy.

Diffuse Cutaneous Mastocytosis: A Current Understanding of a Rare Disease.

Mastocytosis is a heterogeneous disease characterized by the expansion and accumulation of neoplastic mast cells in various tissues. Diffuse cutaneous mastocytosis (DCM) is a rare and most severe form of cutaneous mastocytosis, which typically occurs in childhood. There have been reports of a familial DCM with specific gene mutations, indicating both sporadic and hereditary factors involved in its pathogenesis. DCM is associated with severe MC mediator-related symptoms and an increased risk of anaphylaxis. The diagnosis is based on the appearance of skin lesions, which typically show generalized thickening, erythroderma, blistering dermographism, and a positive Darier's sign. Recognition, particularly in infants, is challenging due to DCMs resemblance to other bullous skin disorders. Therefore, in unclear cases, a skin biopsy is crucial. Treatment focuses on symptom management, mainly including antihistamines and mast cell stabilizers. In extremely severe cases, systemic steroids, tyrosine kinase inhibitors, phototherapy, or omalizumab may be considered. Patients should be equipped with an adrenaline autoinjector. Herein, we conducted a comprehensive review of literature data on DCM since 1962, which could help to better understand both the management and prognosis of DCM, which depends on the severity of skin lesions, intensity of mediator-related symptoms, presence of anaphylaxis, and treatment response.

Evaluation of Ki67, Bax, Bcl-2 and KIT in canine cutaneous mast cell tumours and their relationship with histopathology and prognosis.

Canine cutaneous mast cell tumours (CCMCTs) are common in dogs and exhibit many unpredictable behaviors. This study aimed to encourage pathology laboratories in developing countries to routinely assess prognosis by applying commonly used histopathological grading systems and immunohistochemistry (IHC) markers. We performed histological grading according to both the Patnaik and Kiupel systems, determined the mitotic count (MC) and carried out IHC for the detection of Ki67, Bax, Bcl-2 and KIT in 54 CCMCT cases. MC was associated with both grading systems in terms of survival following diagnosis and prognostic factors differed among cases categorized by the cut-off value of 5. KIT patterns were associated with grading systems and MC. The cohort with pattern II had a lower survival rate than those with patterns I and III. Ki67 was associated with survival when evaluated over the cut-off value of 0.018. Bax expression was associated with both grading systems. Median survival time was longer in patients with lower Bax expression level. Immunohistochemical detection of KIT, Ki67 and Bax improves histopathology in predicting the prognosis. If IHC is unavailable, reports regarding MC and values from both grading systems are the most effective, convenient and cost-effective way to provide the most reliable prognostic data and guidance for the clinicians.

[MACULOPAPULAR CUTANEOUS MASTOCYTOSIS HARBORING A KIT MUTATION (ASP419DEL): A CASE REPORT].

A 2-year-old, male patient presented with an 18-month history of scattered, brown macules and nodules up to 2 cm in size on his trunk and extremities. These macules were accompanied by pruritus and were positive for Darier's sign. A skin biopsy of a brown macule on the left thigh revealed a dense accumulation of CD117-positive, round or oval cells with amphophilic cytoplasm within the upper to middle dermis. The patient was otherwise healthy and had normal laboratory and imaging test results. Sequence analysis of genomic DNA from a skin biopsy demonstrated the presence of an Asp419del mutation in exon 8 of the KIT gene. Based on these findings, maculopapular cutaneous mastocytosis (MPCM) was diagnosed. The patient received H 1-antihistamine. Although the pruritus resolved, the brown macules remained for one year after the initial treatment. To the best of our knowledge, only three cases of cutaneous mastocytosis (CM) with an Asp419del mutation, including the present case, have been reported in the Japanese literature to date; moreover, while the previous two cases were of DCM, the present case was the first instance of MPCM. Normally, the symptoms of childhood-onset MPCM are dormant until puberty. However, a recent study reported that many MPCM patients may experience persistent or exacerbated symptoms. The present study therefore evaluated 53 Japanese cases of childhood onset MPCM with a KIT gene mutation and discussed the patients' clinical outcomes.

Cutaneous mastocytosis in 8 young dogs and review of literature.

Cutaneous mastocytosis (CM) is a rare condition in young dogs characterized by multicentric cutaneous proliferation of neoplastic mast cells. Clinical data from 8 dogs that met inclusion criteria (age of onset less than 1.5 years, greater than 3 lesions) were obtained via a standardized survey. Biopsy samples were classified by the Kiupel/Patnaik grading systems and analyzed for c-KIT mutations. The median age of onset was 6 months (range: 2-17 months). Dogs had 5 to more than 50 lesions characterized as nodules, plaques, and papules. Seven dogs were pruritic. Clinical staging in 2 dogs did not reveal visceral involvement. No dogs had systemic illnesses at diagnosis. Histologically, CM was similar to cutaneous mast cell tumor (cMCT). Two dogs had neoplasms classified as high-grade/grade II while 6 dogs had low-grade/grade II neoplasms. No dogs had mutations in c-KIT exons 8 and 11. Treatment included antihistamines (8/8), corticosteroids (7/8), lokivetmab (3/8), and toceranib (1/8). Six dogs were alive with lesions at the end of the study with a median follow-up time of 898 days, while 2 dogs were euthanized. In dogs with high-grade/grade II neoplasms, one continued to develop lesions at 1922 days post-diagnosis, while the other dog was euthanized at 56 days post-diagnosis. One dog was euthanized 621 days post-diagnosis due to rupture of a neoplasm. CM occurs in young dogs and is histologically indistinguishable from cMCT. Current histologic grading systems did not apply uniformly to the dogs of the study and further studies are needed.

A widespread blistering eruption: diffuse cutaneous mastocytosis.

Diffuse cutaneous mastocytosis with bullous formation is a rare childhood disease. We report a 5-month-old male who presented with a 3-week history of cutaneous bullae and pruritus. On examination, he had erythema of the cheeks bilaterally and diffuse slightly hyperpigmented, indurated skin on his trunk and abdomen. There were tense vesicles, bullae, and erosions linearly arranged on his trunk and extremities. Both the laboratory and imaging workup were normal. Subsequently, a punch biopsy of a vesicle on the abdomen was obtained and findings confirmed a diagnosis of diffuse cutaneous mastocytosis. An EpiPen(r) was prescribed due to the slightly increased anaphylaxis risk compared to other forms of mastocytosis. There are many purported triggers of diffuse cutaneous mastocytosis and there is currently no known cure which makes management of this disease challenging. This case highlights a rare condition for which official treatment guidelines do not exist. A prompt dermatologic diagnosis is necessary to ensure proper workup and regulation is in place.

Histopathological characteristics are instrumental to distinguish monomorphic from polymorphic maculopapular cutaneous mastocytosis in children.

BACKGROUND: Mastocytosis is characterized by the accumulation of mast cells (MCs) in the skin or other organs, and can manifest at any age. A significant number of paediatric mastocytosis cases persist after puberty. In particular, monomorphic maculopapular cutaneous mastocytosis (mMPCM) is often persistent and associated with systemic mastocytosis. However, clinical differentiation of MPCM from polymorphic (p)MPCM can be difficult. AIM: To identify histopathological features that can help to distinguish mMPCM from other subtypes of paediatric mastocytosis. METHODS: This was a retrospective study using skin biopsies from patients with any subtype of mastocytosis. The localization and density of the MC infiltrate, MC morphology and expression of aberrant markers were evaluated and correlated with clinical characteristics. RESULTS: In total, 33 biopsies were available for evaluation from 26 children [(10 with mMPCM, 5 with mastocytoma, 3 with diffuse cutaneous mastocytosis (DCM), 8 with pMPCM)] and 7 adults with MPCM. The MC number was increased in all patients, but was higher in children than adults (P < 0.01). The presence of mMPCM was associated with sparing of the papillary dermis from MC infiltration, whereas MC density in the papillary dermis was highest in pMPCM and DCM (P < 0.01). The positive predictive value of the presence of a reticular MC infiltrate for mMPCM was 72.7% (95% CI 51.4-87.0), and the negative predictive value was 83.3% (95% CI 42.2-97.2). There were no relevant differences in the expression of CD2, CD25 or CD30 between the different subtypes. CONCLUSION: Skin histopathology might enhance the phenotypical differentiation of mMPCM from other subtypes in children, thereby increasing the accuracy of one's prognosis.

Validation of dermatopathological criteria to diagnose cutaneous lesions of mastocytosis: importance of KIT D816V mutation analysis.

BACKGROUND: Cutaneous lesions of mastocytosis (CLM) are often subtle and may require biopsy. However, dermatohistopathological criteria for CLM remain undefined. OBJECTIVES: To establish criteria for CLM by validating histological and molecular parameters. METHODS: In skin samples from Caucasian patients with CLM and controls (atopic dermatitis, chronic urticaria, pruritus, tissue from tumor safety margin excisions), mast cell (MC) numbers, size, shape, distribution, immunostainability with a large panel of markers, pigmentation and presence of KIT D816V mutation were analysed. RESULTS: Forty-seven CLM patients (32 maculopapular cutaneous mastocytosis (MPCM), 15 mastocytomas) and 36 controls were included. Mastocytomas were easily identified by densely packed cuboidal MCs. In MPCM, skin MC density in CD117 stains was higher in CLM patients than in controls (P < 0.0001) and values correlated closely (r = 0.65, P < 0.0001) to results in tryptase stains. The optimized upper dermis cut-off number of 62 MC/mm2 had a sensitivity and specificity of 92% in both stainings, corresponding to approximately 12 MC/high power field (HPF). MC size was larger in MPCM than in controls (P = 0.01). Interstitial (= not perivascular or periadnexal) MCs and stronger basal pigmentation of the epidermis were indicative of MPCM (P < 0.0001 each) and clusters of >3 nucleated MC/HPF exclusively found in MCPM. Surface markers CD2, CD25 and CD30 stained T-lymphocytes, but only negligibly CLM MC. The KIT D816V mutation in formalin fixed paraffin embedded (FFPE) skin was evaluable in 87.5% of MCPM patients and had both 100% sensitivity and specificity. CONCLUSIONS: MPCM can be predicted by major and minor criteria combined in a scoring model. Presence of D816V mutation in FFPE skin and MC density > 27/HPF are >95%-specific major criteria for MPCM. MC densities 12/HPF, interstitial MC, clusters and basal pigmentation are minor criteria.

Cutaneous mastocytosis in a child with a de novo GNB1 mutation.

In the last few years, de novo mutations in the GNB1 gene have been found to cause a neurodevelopmental disorder typically characterized by global developmental delay and hypotonia. Only 4 cases of maculopapular cutaneous mastocytosis in children with GNB1 mutations have been reported to date. Here, we describe another case of the condition with concomitant cutaneous mastocytosis.

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 CHILD CASE OF DIFFUSE CUTANEOUS MASTOCYTOSIS].

Cutaneous mastocytosis (CM) usually appears in childhood and improves substantially before adolescence. The c-KIT mutation of D816V is present in 36% and 20% of patients with childhood-onset CM and diffuse cutaneous mastocytosis (DCM), respectively. In some cases of childhood-onset DCM, the disease can progress to systemic mastocytosis; in others, it resolves spontaneously. Thus, assessing the prognosis is difficult. Herein, we described a case of DCM in an 11-month-old, male patient without a c-KIT mutation. The patient presented with dark brown macules and sporadic erythema topped by bullous lesions. A skin biopsy of the macule on the abdomen revealed accumulation of mast cells which were round to oval-shaped with amphophilic cytoplasm within the upper dermis. The patient had received H1 inhibitor until age 3 years and continued to experience blisters on the trunk. However, no severe symptoms, such as anaphylaxis, occurred. Included in this manuscript is a review of previous reports of childhood-onset DCM in Japan and cases specifically seen at our dermatology clinic.

Telangiectasia Macularis Eruptiva Perstans of the Scalp Mimicking Angiosarcoma.

ABSTRACT: We present a case of a 74-year-old man with marked photodamage who was ultimately diagnosed with telangiectasia macularis eruptiva perstans (TMEP) of the scalp. The diagnosis was made more difficult because of the clinical and histological similarity of this case with an early angiosarcoma. TMEP is a benign and indolent rare subtype of cutaneous mastocytosis presenting clinically with red-brown telangiectatic macules, usually symmetrically distributed over the trunk and extremities. Although most cases are limited to the skin, systemic involvement can occur, and this can be a potentially life-threatening disease. Although also rare, in contrast to TMEP, cutaneous angiosarcoma is a highly malignant vascular tumor with a poor prognosis. This case highlights the importance of including TMEP on the differential diagnosis where vascular lesions of the scalp are observed.

Pediatric maculopapular cutaneous mastocytosis: Retrospective review of signs, symptoms, and associated conditions.

BACKGROUND/OBJECTIVES: Though maculopapular cutaneous mastocytosis is the most common form of pediatric mastocytosis, it remains unclear which patients will experience severe symptoms. We sought to better define the presentation and the cutaneous and systemic signs and symptoms in patients with maculopapular cutaneous mastocytosis. METHODS: We analyzed retrospective data on 227 patients diagnosed with maculopapular cutaneous mastocytosis prior to age 15 years from five US clinical sites. We collected data on signs, symptoms, age of onset, and laboratory testing. RESULTS: Median age of onset of maculopapular cutaneous mastocytosis was 3 months, with 94% of patients presenting prior to age 2 (range 0-15 years). Patients presenting before age 2 had significantly lower serum tryptase level (P = .019). Greater number of skin lesions (P = .006), number of reported skin signs and symptoms (P < .001), and higher tryptase levels (P < .001) were associated with more systemic symptoms. CONCLUSION: Children with maculopapular cutaneous mastocytosis, who have greater skin involvement, higher serum tryptase level, and more skin signs and symptoms, are more likely to have systemic symptoms.

Cutaneous mastocytosis: A dermatological perspective.

Mastocytosis is a rare disease characterised by expansion and collection of clonal mast cells in various organs including the skin, bone marrow, spleen, lymph nodes and gastrointestinal tract. The prevalence of mastocytosis has been estimated to be one in 10 000, while the estimated incidence is one per 100 000 people per year. Cutaneous mastocytosis is classified into (i) maculopapular cutaneous mastocytosis, also known as urticaria pigmentosa; (ii) diffuse cutaneous mastocytosis; and (iii) mastocytoma of the skin. In adults, cutaneous lesions are usually associated with indolent systemic mastocytosis and have a chronic evolution. Paediatric patients, on the contrary, have often cutaneous manifestations without systemic involvement and usually experience a spontaneous regression. Diagnosis of cutaneous mastocytosis may be challenging due to the rarity of the disease and the overlap of cutaneous manifestations. This short review describes pathogenesis and clinical aspects of cutaneous mastocytosis with a focus on diagnosis and currently available therapies.

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.

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.

New Approach to Paediatric Mastocytosis: Implications of KIT D816V Mutation Detection in Peripheral Blood.

is missing (Short communication).

Simultaneous occurrence of cutaneous mastocytosis and juvenile xanthogranuloma in a child: Random or true association?

Juvenile xanthogranuloma (JXG) and cutaneous mastocytosis (CM) are two distinct conditions that have rarely been reported in association. We report a child with CM and disseminated JXG, who showed a significant decrease in serum tryptase levels and regression of JXG lesions over time. Due to the paucity of reports, a true association between these two conditions has not been validated, although a potential induction of histiocytic lesions by mast cell degranulation has been proposed.