[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.

Genotypic and phenotypic characteristics of Chinese neonates with cutaneous mastocytosis: a case report and literature review.

Mastocytosis is an accumulation of clonal mast cells within tissues and it is most commonly caused by an activating mutation in the KIT gene. In this study, we report a neonatal case who presented with diffuse cutaneous mastocytosis (CM) at birth. In China, nine other cases of neonatal-onset CM have been reported in the literature since 2006. In those cases, diffuse CM and urticaria pigmentosa were the main symptoms, and mutations in exon 17 at codon 816 in KIT were identified.

Paediatric mastocytosis: long-term follow-up of 53 patients with whole sequencing of KIT. A prospective study.

BACKGROUND: Mastocytosis is a heterogeneous group of clinical disorders characterized by the abnormal accumulation of mast cells. The adult and paediatric forms differ in their clinical and genetic features and outcomes. OBJECTIVES: To describe the clinical evolution of a well-characterized cohort of paediatric mastocytosis (PM), and to analyse the relationship between KIT mutation and the clinical course. METHODS: This was a prospective cohort study performed at the National Clinical Reference Center for Mastocytosis. Diagnosis was confirmed by identification of KIT mutation on lesional skin biopsy. Mastocytosis subtype, mast cell mediator-related symptoms (MC MRS) and clinical course were recorded. Fifty-three patients with PM and > 4 years of disease course were enrolled. The mean ± SD age at the final evaluation was 13·2 ± 4·8 years. The main outcome was the type of KIT mutation as a predictor of evolution and clinical characteristics. RESULTS: Patients presented with maculopapular cutaneous mastocytosis (n = 44), diffuse cutaneous mastocytosis (n = 6) or mastocytoma (n = 3). The mean duration of disease was 12·1 years. Substantial or partial cutaneous regression (18 of 53 and 16 of 53), stabilization or aggravation (16 of 53) and complete cutaneous regression (three of 53) were noted. MC MRS mainly regressed (21 of 53). For 22 patients, evolution of MC MRS and evolution of cutaneous lesions were different. No significant association between evolution and KIT mutation or between evolution and type of cutaneous mastocytosis was found. A late onset of the disease (after 2 years) is associated with worse evolution. CONCLUSIONS: PM is not systematically self-regressive. MC MRS manifestations and cutaneous lesions can persist or increase overtime. KIT mutation is not a predictor of evolution.

Overexpression of p16(INK4a) in Mastocytosis (Urticarial Pigmentosa).

The expression of p16(INK4a) has been reported to induce cell-cycle arrest and cellular senescence. The p16(INK4a) expression has never been examined in human mast cells and mastocytosis. We immunohistologically examined the expression of p16(INK4a) and tryptase in 5 normal human skin and 4 mastocytosis. In normal mast cells, only 5.9 ± 3.4 (mean ± standard deviation) % of tryptase-positive mast cells coexpressed p16(INK4a). However, significantly higher percentage (86.0 ± 14.1%) of tryptase-positive tumor cells was immunoreactive to p16(INK4a) in all of 4 mastocytosis. The p16(INK4a) overexpression may induce the senescence of neoplastic mast cells to undergo spontaneous regression of mastocytosis.

Large maculopapular cutaneous lesions are associated with favorable outcome in childhood-onset mastocytosis.

BACKGROUND: Mastocytosis, characterized by pathologic accumulation of mast cells, can manifest itself in adulthood or childhood. Pediatric patients usually have cutaneous mastocytosis (CM) with mast cell infiltrates limited to the skin and spontaneous improvement of skin lesions after several years. However, there are some patients with persistent disease resembling adulthood-onset mastocytosis. OBJECTIVE: The current classification of CM differentiates between 3 subforms. In clinical practice we noticed that different variants of these subforms might exist, particularly in patients with childhood-onset mastocytosis. Therefore, in the present study, we aimed to investigate whether specific cutaneous lesions in patients with childhood-onset mastocytosis are associated with other disease parameters. METHODS: We analyzed 144 patients with a disease onset of less than age 17 years using a systematic dermatologic approach. RESULTS: One hundred twenty-two patients presented with maculopapular cutaneous mastocytosis (MPCM), 12 patients presented with diffuse CM, and 10 patients presented with solitary mastocytoma of the skin. Patients with MPCM showed particularly heterogeneous cutaneous lesions and were therefore grouped into 3 variants presenting either with small lesions (MPCM-small, skin lesions <1 cm in diameter; n = 19), large lesions (MPCM-large, skin lesions ≥ 1 cm in diameter; n = 89), or atypical lesions (MPCM-other, n = 14). Patients with MPCM-large lesions, compared with those with MPCM-small lesions, were characterized by significantly lower tryptase levels, shorter disease duration, and earlier disease onset. In addition, more patients with MPCM-large lesions exhibited spontaneous regression of cutaneous lesions. CONCLUSION: Our data show that patients with MPCM-large lesions compared with those with MPCM-small lesions have a more favorable disease course and suggest exploring the size of cutaneous lesions as a prognostic parameter in childhood-onset MPCM.

Role of imatinib in the treatment of pediatric onset indolent systemic mastocytosis: a case report.

BACKGROUND: Mastocytosis is a sporadic disease characterized by an abnormal accumulation of mast cells (MCs) in single or multiple organs. It has a heterogeneous clinical picture which is a reflection of underlying tissue MC burden, mediators released and the organs involved. Here, the authors report significant symptomatic, cutaneous and systemic response to imatinib in a case of childhood onset indolent D816V KIT unmutated systemic mastocytosis (SM). CASE REPORT: A 19-year-old female presented with a history of itchy skin lesions over the face, trunk and extremities since 6 months of age associated with recurrent bouts of angioedema. The skin and bone marrow examination were consistent with mastocytosis. No pathogenic mutations were detected in exons 8 and 17. In view of the severity of cutaneous symptoms and evidence of bone marrow involvement, she was treated with imatinib which resulted in marked improvement. CONCLUSION: Imatinib has a therapeutic role in the presence of an imatinib-sensitive KIT mutation or in KIT816-unmutated patients with aggressive SM. Its role in the treatment of indolent and cutaneous mastocytosis is less well established. However, the authors have demonstrated the usefulness of imatinib in the treatment of c-KIT-negative indolent SM with extensive cutaneous involvement.

Familial urticaria pigmentosa: report of a family and review of the role of KIT mutations.

Cutaneous mastocytosis is a rare clinically heterogeneous disorder characterized by mast cell infiltration. Mastocytosis affects both children and adults and has been reported to occur in families. Recent data suggest that mutations in the c-kit proto-oncogene are causative of mastocytosis not only in adults but in children and familial cases as well; however, mutation analysis other than D816V is not widely available, making detection of causative mutations problematic. We present the case of a 33-year-old man with a 30-year history of persistent urticaria pigmentosa and his 2 affected children. Sequencing of KIT exons 8, 10, 11, and 17 was carried out on a skin biopsy specimen and mucosal swabs of the incident case and was negative for known KIT mutations. Additional work-up was deferred by the family. Presentation of this familial case of urticaria pigmentosa demonstrates the complexity of genetic evaluation in clinical settings. It suggests that mutations other than those reported in exons 8, 10, 11, and 17 may also result in familial mastocytosis. Presentation of this case also allows for review of the mechanism of action of causative KIT mutations and the recent literature supporting KIT mutations in childhood and familial mastocytosis.

Differential diagnoses of systemic mastocytosis in routinely processed bone marrow biopsy specimens: a review.

Diagnosis of systemic mastocytosis (SM) is mainly based on the morphological demonstration of compact mast cell infiltrates in various tissue sites. In almost all patients such infiltrates are detected in the bone marrow. Reliable immunohistochemical markers for the diagnosis and grading of SM have been established, but various differential diagnoses including myeloproliferative neoplasms, basophilic and eosinophilic leukemias may be very difficult to delineate. Even more challenging is the recognition of hematological neoplasms with signs of mast cell differentiation but not fulfilling diagnostic criteria for SM, especially the rare myelomastocytic leukemia. It is also important to separate the reactive state of mast cell hyperplasia from indolent variants of SM, especially those with a very low degree of bone marrow infiltration and absence of compact mast cell infiltrates. When the lymphocytic component of the SM infiltrate is very prominent, SM may be confused with an indolent lymphoma, especially lymphoplasmacytic lymphoma which almost always shows a marked reactive increase in mast cells. In aggressive and leukemic variants of SM, mast cells may be very atypical and devoid of metachromatic granules. This hypogranulation can be regarded as cellular atypia and may lead to the misdiagnosis aspect of monocytic leukemia or histiocytic neoplasm. Regarding immunohistochemical anomalies, mast cells in aggressive and leukemic SM have been found to express CD30 (Ki1-antigen). Thus, anaplastic large cell lymphoma or Hodgkin's disease may first be considered rather than SM. There is increasing evidence that most patients with long-standing adult-type urticaria pigmentosa-like skin lesions have in fact indolent SM. Therefore, such skin lesions are an important clue to the correct diagnosis in these patients. However, in aggressive or leukemic SM skin lesions are usually absent and then the correct diagnosis relies on an appropriate investigation of bone marrow biopsy specimens using both SM-related immunohistochemical markers (tryptase, KIT, CD25, CD30) but also markers excluding potential differential diagnoses. Investigation for presence of the activating KIT point mutation D816V is very helpful to establish a correct diagnosis of SM in all the difficult cases exhibiting a low degree of bone marrow infiltration or puzzling morphological findings.

[Urticaria pigmentosa: a current approach]. / Urticaria pigmentosa: un enfoque actual.

The term urticaria pigmentosa (UP) denotes a heterogeneous group of disorders characterized by abnormal growth and accumulation of mast cells (MC) in the skin. Symptoms result from MC chemical mediator's release, pathologic infiltration of neoplastic MC in tissues or both. Multiple molecular, genetic and chromosomal defects seem contribute to an autonomous growth, but somatic c-kit D816V mutation is more frequently found, especially in systemic disease. The aim of this paper is to provide a current overview for a better understanding of the symptoms associated with this disease, to describe its classification, recent advances in its pathophysiology and its treatment.

Serum tryptase and SCORMA (SCORing MAstocytosis) Index as disease severity parameters in childhood and adult cutaneous mastocytosis.

BACKGROUND: Skin lesions are the predominant clinical feature of the commonest form of mastocytosis. Mastocytosis is classified according to World Health Organization criteria. Determination of the levels of mast-cell mediators or their metabolites reflects the mast-cell burden. The extent of cutaneous mastocytosis can be assessed clinically using a scoring system (SCORing MAstocytosis; SCORMA Index) that we have developed. OBJECTIVE: Serum tryptase levels were compared with the SCORMA Index in a large group of paediatric and adult patients to investigate whether there was any correlation between the two. METHODS: The SCORMA Index in 64 patients (31 children and 33 adults) was compared with serum tryptase levels. The results of the first visit at which SCORMA and tryptase were evaluated were analysed. RESULTS: There was a positive correlation between the SCORMA Index and serum tryptase levels, indicating the value of the SCORMA Index in the assessment of mastocytosis with skin involvement. CONCLUSION: The results of this study showed that the SCORMA Index is a useful tool for evaluating the severity of cutaneous mastocytosis. The correlation between the SCORMA Index and serum tryptase levels underlines the benefit of the SCORMA Index as a clinical tool. Repeated SCORMA Index measurements can provide a rapid impression of changes in the clinical state of mastocytosis. This is particularly relevant in children, because taking blood samples from this group is much more difficult. The well-established methods for evaluation of disease severity may be expanded by the rapid SCORMA Index method.

Neonatal mastocytosis with pachydermic bullous skin without c-Kit 816 mutation.

BACKGROUND: Bullous mastocytosis is an unusual variant of mast cell disease with widespread bullae as the main cutaneous feature induced by mast cell proteases that cause dermoepidermal separation. CASE REPORT: A rare case of diffuse cutaneous bullous mastocytosis with pachydermia and unusually extensive skin folding is described in a 3-week-old girl. The diagnosis was confirmed by immunohistochemistry with Giemsa stain, the naphthol ASD chloroacetate esterase reaction and elevated blood levels for tryptase, histamine in serum and histamine and 1.4-methylimidazol acetic acid in the 24-hour urine. Blood cell count was normal, as were thrombocytosis and leukocytosis. FACS analysis of the bone marrow aspiration material showed 1% mast cells. No c-Kit 816 [Asp-->Val] somatic mutation was found. Systemic involvement of other organs was excluded. DISCUSSION: The prognosis of c-Kit-negative diffuse bullous mastocytosis is not known. Regular blood controls are mandatory, and screening for germ cell ovarian cancer and bone marrow controls should be performed as well.

One-step detection of c-kit point mutations using peptide nucleic acid-mediated polymerase chain reaction clamping and hybridization probes.

The prognostic significance of somatic activating codon 816 c-kit mutations in pediatric urticaria pigmentosa has not yet been established in detail. Detection of such mutations in archival paraffin-embedded biopsies is usually hampered by an abundance of surrounding normal cells. Here we describe a method for the selective amplification and specific detection of c-kit mutation Asp816-->Val in complete tissue sections cut from up to 24-year-old paraffin blocks. Peptide nucleic acid-mediated polymerase chain reaction clamping of the wild-type allele was combined with on-line mutation detection using oligonucleotide hybridization probes. In DNA extracted from HMC-1 cells heterozygously carrying the c-kit mutation Asp816-->Val, the one-tube assay allowed specific detection of this mutation in a more than 1000-fold excess of normal background DNA within 1 hour and without the need for additional analytical steps. In a series of 38 cases with pediatric urticaria pigmentosa we detected c-kit codons 815 and 816 mutations in 16 cases. Mutation detection did not correlate with clinical outcome after a mean follow-up of 11.2 years. In conclusion, the procedure described may represent an ideal screening tool for all kinds of clinical applications, using point mutations as markers of, for example, early events in carcinogenesis, circulating metastatic tumor cells, and minimal residual disease.

Familial urticaria pigmentosa associated with thrombocytosis as the initial symptom of systemic mastocytosis and Down's syndrome.

Most cases of urticaria pigmentosa are confined to the skin, but visceral involvement and/or haematological abnormalities have been observed. It is still a matter of debate whether all forms of mastocytosis are true neoplasias or reactive hyperplasias. Familial inheritance of urticaria pigmentosa is rare. We report on a fraternal set with urticaria pigmentosa as part of a systemic mastocytosis. The first patient additionally revealed persistent thrombocytosis and splenomegaly. His brother developed urticaria pigmentosa, intermittent diarrhoea, hepatomegaly and asthma bronchiale associated with trisomy 21 (Down's syndrome). The association of mastocytosis with thrombocytosis has seldom been described. In our patient it preceded the development of systemic mastocytosis. The association with Down's syndrome has not been reported until now.

Germline mutation in the juxtamembrane domain of the kit gene in a family with gastrointestinal stromal tumors and urticaria pigmentosa.

BACKGROUND: Gain-of-function mutations of the c-kit protooncogene, mainly clustered in the juxtamembrane domain, have been reported in a significant fraction of gastrointestinal (GI) stromal tumors (GISTs) that represent the most common mesenchymal tumor of the GI tract. Two families also have been described with a GIST predisposition syndrome with a germline c-kit mutation affecting either the juxtamembrane domain or the tyrosine kinase domain. Here, the authors report on a family in which the dominantly inherited trait of hyperpigmented spots was inherited from an individual who developed multiple GISTs with diffuse hyperplasia of the myenteric plexus by his son, who was affected with urticaria pigmentosa. METHODS: Screening for the c-kit mutation was performed by means of polymerase chain reaction-based denaturing gradient gel electrophoresis/constant denaturing gel electrophoresis followed by direct sequencing of abnormal conformers. Expression of KIT and CD34 was determined by immunohistochemistry. RESULTS: In peripheral blood DNA samples, both affected family members showed a previously undescribed c-kit mutation in the juxtamembrane domain, resulting in the substitution of alanine for valine(559). Mutation and polymorphic marker analyses on DNA samples from three GISTs and two skin biopsy specimens evidenced the same mutation in the heterozygous condition. Immunohistochemical examination showed coexpression of CD117 (c-kit) and CD34 in all independent GISTs and CD117 positivity in mast cells from the skin lesions. CONCLUSIONS: Comparative analysis of clinical presentation and mutation mapping in the families described to date point to the peculiar association of mast cells, melanocytic dysfunction, and GIST predisposition in carriers of c-kit mutations within the juxtamembrane domain.