[Isolated mastocytoma in children: a case study]. / Mastocytome solitaire de l'enfant: à propos d'un cas.

Isolated mastocytoma is the most common form of mastocytosis in children. Prognosis is good, as in all other forms of mastocytosis in children, with possibility of spontaneous regression. Dermocorticoids can accelerate this regression, as it is the case for our patient.

Safety and efficacy of intralesional triamcinolone administration for treatment of mast cell tumors in dogs: 23 cases (2005-2011).

OBJECTIVE To evaluate the safety and efficacy of intralesional triamcinolone administration, as a sole or adjuvant treatment, in dogs with mast cell tumors. DESIGN Retrospective case series ANIMALS 23 dogs with mast cell tumors. PROCEDURES Medical records of dogs treated for a confirmed diagnosis of a mast cell tumor between 2005 and 2011 were reviewed. Patients with a confirmed diagnosis and measurable disease (tumor longest dimension ≥ 0.5 cm) that had received ≥ 1 intralesional treatment with triamcinolone, regardless of prior, concurrent, or adjuvant treatments, were eligible for inclusion. Data collected included patient characteristics, results of cytologic and histologic testing and tumor staging, triamcinolone dosage, treatment response, and adverse events. RESULTS 23 dogs with 24 tumors were included. Tumors were treated by means of intralesional triamcinolone administration alone (n = 5), intralesional triamcinolone administration with concurrent oral administration of glucocorticoids (6), and intralesional triamcinolone administration with concurrent cytotoxic chemotherapy, with or without oral administration of corticosteroids and radiation therapy (13). Of 5 dogs treated with intralesional triamcinolone administration alone, 1 achieved a complete response, 3 achieved a partial response, and 1 maintained stable disease. The response rate for all 24 tumors (23 dogs) was 67% (16/24), including 4 with a complete response and 12 with a partial response. The median time to progression was 63 days (range, 6 to 447 days). Three dogs experienced adverse events (local hemorrhage [n = 1]; suspected gastrointestinal ulceration [2]). CONCLUSIONS AND CLINICAL RELEVANCE Intralesional triamcinolone administration may be well tolerated and effective for treatment of nonresectable mast cell tumors in dogs.

Topical corticosteroids versus "wait and see" in the management of solitary mastocytoma in pediatric patients: a long-term follow-up.

Management of patients affected by mastocytoma (MS) includes avoiding triggering factors of mast cell degranulation, and administration of symptomatic treatment. We evaluated topical steroid treatment efficiency on the clinical course of MS in a group of patients, comparing the results with another untreated group.We retrospectively evaluated clinical data of 176 patients under 15 years of age, affected by MS and referred to our Dermatological Pediatric Service from 1996 to 2010. Ninety-one of 176 children were treated with topical steroids. Follow-up was possible in 130 of 176 patients and lasted for 56.3 months on average. We compared 62 treated and 68 untreated patients. There was not statistic difference between the two groups: (i) in the number of healed or partially improved cases; and (ii) in the time of partial regression, although it is quicker with therapy. The time of healing is 16.4 months (on average) with treatment, and 34.7 months (on average, p = 0.001) without any treatment. The resolution of MS is independent of therapy administration, but the time of healing is statistically faster using the local steroids. An appropriate treatment with them is effective and safe, considering the long time needed for spontaneous resolution.

Ex vivo evaluation of imatinib mesylate for induction of cell death on canine neoplastic mast cells with mutations in c-Kit exon 11 via apoptosis.

Several studies of canine spontaneous mast cell tumours have described mutations in the c-kit proto-oncogene. These mutations produce a constitutively activated product and have been suggested to play a role in the malignant transformation of mast cells. We hypothesize that the selective tyrosine kinase inhibitor imatinib mesylate inhibits signal transduction and induces apoptosis when tested in cutaneous canine mast cell tumour samples positive for mutation in c-kit exon 11. Three-dimensional ex vivo cultures of canine grade II mast cell tumour treated with STI-571 at 48, 72, and 96 h and tested for signal transduction and apoptosis using appropriate assays were used. There was a progressive and significant increase in caspase-3 and TUNEL-positive mast cells compared to the untreated cultures. Additionally, a concurrent reduced expression of Ki67 and BCL-2 was observed. Furthermore, the treated cultures showed a marked reduction of Kit expression. Our results demonstrate that STI-571 induces Caspase-dependent apoptosis in a canine neoplastic mast cells possessing mutations in c-kit exon 11.

Imatinib elicited a favorable response in a dog with a mast cell tumor carrying a c-kit c.1523A>T mutation via suppression of constitutive KIT activation.

Target therapy using the tyrosine kinase inhibitor imatinib is one of the new therapeutic approaches for canine mast cell tumors (MCTs). In the present report, we demonstrate a clinical response to imatinib in a dog with MCT carrying a c-kit c.1523A>T mutation. Moreover, the effect of this mutation on the phosphorylation status of KIT and the inhibitory potency of imatinib on the phosphorylation of the mutant KIT were examined in vitro. A dog with a MCT tumor mass on the right forelimb sole with lymph node metastasis and mastocytemia was treated with imatinib. The MCT mass markedly shrank and mastocytemia became undetectable with 2 weeks of treatment. The lymph node enlarged by metastasis became normal in size with 5 weeks of treatment. From the sequencing analysis of c-kit in tumor cells, a substitution mutation c.1523A>T that alters the amino acid composition (p.Asn508Ile) within the extracellular domain of KIT was identified. The mutant KIT expressed on 293 cells showed ligand-independent phosphorylation and imatinib suppressed this phosphorylation in a dose-dependent manner. From these findings, imatinib was considered to elicit a clinical response in a canine case of MCT via inhibition of the constitutively activated KIT caused by a c-kit c.1523A>T mutation.

A 3-month-old with a blistering plaque.

Cutaneous Mastocytosis is not an uncommon condition in the pediatric setting. The eruption can have multiple clinical presentations. We present a case of a 3-month-old child with a solitary mastocytoma who was initially diagnosed with recurrent bullous impetigo. Solitary mastocytoma can present as a blister. Although bullous impetigo is a common diagnosis in children and it would be tempting to make that diagnosis in the presence of a positive skin swab culture, clinicians always have to be mindful of secondary impetiginization of another primary skin disease process.

Phase II open-label study of single-agent hydroxyurea for treatment of mast cell tumours in dogs.

This prospective study evaluated the efficacy and safety of hydroxyurea (HU) in dogs with measurable mast cell tumours (MCTs). Dogs were treated with HU at 60 mg kg(-1)per os q24h for 14 days then 30 mg kg(-1) q24h thereafter or until MCT recurrence. Forty-six dogs were enrolled. The overall response rate was 28%. Two dogs had a complete response (CR) for 256 and 448 days, respectively. Eleven dogs had a partial response for a median duration of 46 days (range, 28-189 days). Grade 2 to 4 neutropenia occurred in eight dogs and grade 4 thrombocytopenia in two. Grade 3-4 anaemia occurred in seven dogs; overall, there was a significant decrease in haematocrit after treatment with HU. The median drop in haematocrit was 10%. This study demonstrated that HU has activity in the treatment of MCTs with mild anaemia being the primary adverse event.

Solitary mastocytoma occurring at a site of trauma.

We describe a patient with a solitary mastocytoma arising at a site of trauma. The patient was born with the umbilical cord wrapped around her right thigh and subsequently developed a solitary mastocytoma in the exact site and distribution of this injury. The pathogenesis of mast cell proliferation in solitary mastocytoma is not completely understood. Cytokines released after injury, such as stem cell factor, may stimulate the proliferation of mast cells, as well as fibroblasts and melanocytes to form a mastocytoma. Mast cells in a newborn may be more sensitive to stem cell factor in the presence of cytokines released after injury due to an increased density of c-kit receptors. We present our patient and review the literature to support a hypothesis that this condition represents a reactive, and not neoplastic, process.

Cutaneous mastocytosis in Thai children.

BACKGROUND: Mastocytosis is a disorder of mast cells proliferation within various organs, most commonly in the skin. The disease more commonly appears during infancy than adult. OBJECTIVE: To characterize the clinical features, response to therapy and prognosis of cutaneous mastocytosis in children. MATERIAL AND METHOD: A retrospective study of cutaneous mastocytosis was performed at Queen Sirikit National Institute of Child Health during January 1994 to December 2007.All cases were confirmed by histological diagnosis. RESULTS: There were a total of 50 patients. The male to female ratio was 1:1.2. Age at onset of lesions ranged from birth to 7 years. Forty-seven patients (94%) developed skin lesions within the first year of ife. There were 45 cases (90%) of urticaria pigmentosa, 3 cases (6%) of mastocytoma and 2 cases (4%) of diffuse cutaneous mastocytosis. None of the patient had a family history of cutaneous mastocytosis. Most of the children were healthy, except the one who had germ cell ovarian tumor Skin biopsies were performed in all cases and revealed mast cells infiltrate in the dermis. Treatment included oral antihistamine in all cases. Oral mast cell stabilizers were given in 6 patients (12%) and topical corticosteroids in 15 patients (30%). Four patients (8%) were treated with oral prednisolone. The skin lesions resolved only in 1 patient (2%) at age 7.8 years, the others still had skin lesions without systemic symptoms. CONCLUSION: Cutaneous mastocytosis is a benign disease in children without systemic involvement.

Mastocitoma solitario: Presentación de un caso en el adulto / Solitary mastocytoma: Presentation in an adult

El objetivo de esta publicación es mostrar un caso de mastocitoma solitario en la vejez, debido a la rareza de su aparición en tal etapa. Sus diagnósticos diferenciales y la involución total de la lesión con el uso de apósitos hidrocoloides, son comentados.

We present a case of a solitary mastocytoma in a man 86 years old who developped the lesion on the inferior lip. The interest of the case is the rarity of the presentation in an adult, which presents others differential diagnostics, and the success of the treatment with hidrocolloid dressings.