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.

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.

Longitudinal Study of Pediatric Urticaria Pigmentosa.

BACKGROUND/OBJECTIVES: Urticaria pigmentosa (UP) is the most common form of mastocytosis in children and is associated with systemic signs, symptoms, and triggers. To our knowledge, the effect of UP on children's quality of life has not been studied. The objective of the current study was to characterize the natural history, triggers, and complications of pediatric UP, identify prognostic indicators, and determine its effect on quality of life. METHODS: Between 2002 and 2007, children with three or more mastocytomas diagnosed by a pediatric dermatologist were recruited during visits at the Children's Hospital of Wisconsin Dermatology Clinic (Milwaukee, WI). Research visits were conducted every 3 years and telephone interviews yearly. The Children's Dermatology Life Quality Index was administered to subjects 4 years of age and older at enrollment. Laboratory test results were collected for subjects younger than 4 years at enrollment. Subjects were followed until UP resolution or study end in August 2015. RESULTS: The final cohort size was 43 subjects followed for a median of 8.1 years. Twenty-six subjects were followed through study completion. At age 12 years, 6 patients had disease resolution and 14 remained active. Patients who had disease resolution before age 12 years were more likely to be male and had fewer years of age and smaller lesions, fewer affected areas, and earlier onset. Common medications and anesthetics resulted in no serious reactions. Hymenoptera stings occurred in 51%, with no reports of anaphylaxis. No patient reported a severe effect on quality of life, with most indicating mild to no effect. CONCLUSION: Severe complications are not common with historically identified triggers. Disease does not resolve before adolescence in most children. UP has a minimal effect on quality of life for most children.

General Anesthesia in a Patient With Urticaria Pigmentosa Referred for Electroconvulsive Therapy.

Urticaria pigmentosa is a rare disorder characterized by an abnormal systemic proliferation of mast cells. In this condition, various triggers can induce either cutaneous histamine release, resulting in rash, or generalized histamine release, resulting in symptomatic hypotension, syncope, or in its severest form, an anaphylactoid reaction resistant to most resuscitative measures. Many anesthetic agents and adjuncts are known potential triggers, and patients who require surgery or procedures under anesthesia must be managed carefully. In this review, we describe the safe use of general anesthesia for electroconvulsive therapy in a patient with urticaria pigmentosa and discuss the association between psychiatric disorders and mastocytoses.

Tryptase and histamine metabolites as diagnostic indicators of indolent systemic mastocytosis without skin lesions.

BACKGROUND: Risk indicators of indolent systemic mastocytosis (ISM) in adults with clinical suspicion of ISM without accompanying skin lesions [urticaria pigmentosa (UP)] are lacking. This study aimed at creating a decision tree using clinical characteristics, serum tryptase, and the urinary histamine metabolites methylimidazole acetic acid (MIMA) and methylhistamine (MH) to select patients for bone marrow investigations to diagnose ISM. METHODS: Retrospective data analysis of all adults, in whom bone marrow investigations were performed to diagnose ISM, was carried out. RESULTS: In total, 142 patients were included. SM was absent in all 44 patients with tryptase <10 µg/l, in 45 of 98 (46%) patients with tryptase ≥10 µg/l and in 18 of 52 patients (35%) with tryptase >20 µg/l. Above 43 µg/l, all patients had ISM (n = 11). Male gender, insect venom anaphylaxis as presenting symptom, tryptase, MIMA, and MH were independent ISM predictors. If tryptase was ≥10 µg/l, the diagnostic accuracy of MIMA and MH was high (areas under the ROC curve 0.92). CONCLUSIONS: In suspected patients without UP, the ISM risk is very low (if present at all) if tryptase is <10 µg/l. If tryptase is ≥10 µg/l, this risk depends on MIMA and MH, being low if these are normal, but high if these are elevated. Male gender and insect venom anaphylaxis are additional risk indicators. We recommend refraining from bone marrow examinations in suspected patients without UP if tryptase is <10 µg/l. Our results question the reliability of the minor diagnostic World Health Organization criterion of tryptase >20 µg/l.

Cutaneous mastocytosis associated with congenital alopecia.

Mastocytosis is a rare disorder that shows accumulation of mast cells in tissues. Atypical clinical features may mimic impetigo, Langerhans cell histiocytosis, and carcinoid syndrome; however, only 1 case of scarring alopecia associated with mastocytosis has been reported. We present the first case of cutaneous mastocytosis associated with congenital alopecia areata in a 3-year-old Korean girl. This case showed an atypical clinical presentation of congenital alopecia areata, but histopathological results confirmed the diagnosis of cutaneous mastocytosis.

Juvenile xanthogranuloma: challenges in complicated cases.

Juvenile xanthogranuloma (JXG) is one of the most common forms of non-Langerhans cell histiocytosis in children. Although it usually presents as a self-limited skin lesion with typical histopathology, JXG can be challenging to diagnose due to an atypical initial presentation with corresponding variable histopathology for different stages of development. We present challenging cases of JXG from Sydney Children's Hospital, collected over 10 years - two with multisystem involvement and concomitant urticaria, one associated with neurofibromatosis, and one case of giant JXG with an initial histopathological challenge. Although JXG has been reported with urticaria pigmentosa, in two of our cases persistent urticaria, in association with JXG is discussed.

CD25 expression on cutaneous mast cells from adult patients presenting with urticaria pigmentosa is predictive of systemic mastocytosis.

Urticaria pigmentosa (UP) is a clinicopathologic term used to describe reddish-brown cutaneous macules and papules, characterized histologically by mast cell infiltration of the papillary and upper reticular dermis and reactive basal hyperpigmentation of the overlying epidermis. Although typically a benign, self-limited disorder of childhood, a significant proportion (up to 30%) of adolescent and adult-onset UP represents cutaneous involvement by underlying systemic mastocytosis (SM). Predicting the course of cutaneous mast cell disease has been limited by a lack of diagnostic and prognostic markers. In patients with SM, neoplastic bone marrow mast cells show aberrant surface expression of CD25. However, whether CD25 expression on cutaneous mast cells is associated with underlying SM is unknown. In this study, we performed a clinicopathologic analysis of 30 adult patients presenting with UP between 1987 and 2007. Cutaneous mast cell infiltration pattern, cytomorphology, density, and CD25 immunoreactivity were correlated with underlying or subsequent SM. On the basis of clinical and pathologic follow-up, 10 of 30 (33%) patients were diagnosed with SM and 20 of 30 (67%) with limited cutaneous mastocytosis (CM). Although cutaneous mast cell density was slightly higher in patients with SM compared to those with limited CM (P=0.047), neither mast cell cytomorphology nor infiltration pattern correlated with underlying systemic disease. However, cutaneous mast cells from all 10 patients with SM (100%) were immunoreactive for CD25, compared to only 5 of 20 (25%) with limited CM (P<0.001). Our findings suggest that immunoreactivity for CD25 in cutaneous mast cells may be useful for stratifying adult patients presenting with UP for additional clinical evaluation.

Mastocytosis with urticaria pigmentosa and osteoporosis.

A 76-year-old man with a 52-year history of urticaria pigmentosa was found to have an elevated serum tryptase level as well as osteoporosis. Histopathologic alterations of one his skin lesions showed an infiltrate of mast cells. Urticaria pigmentosa patients are at risk for osteoporosis because of elevated heparin and stem-cell factor levels. These patients should be screened with serum tryptase levels and bone density studies to detect osteoporosis, regardless of their age.

Peripheral interstitial keratitis: a novel manifestation of ocular mastocytosis.

PURPOSE: To report a case of peripheral interstitial keratitis in a patient with mastocytosis. METHODS: Clinical case description and immunohistologic examination of biopsied ocular tissue. RESULTS: A 22-year-old woman with biopsy-proven urticaria pigmentosa, a subset of mastocytosis, presented with an active peripheral interstitial keratitis with vascularization associated with foreign body sensation and itching. Biomicroscopy of the cornea showed deep corneal inflammatory infiltrates and midstromal vascularization adjacent to a region of superior bulbar conjunctiva, which was mildly chemotic and inflamed. Topical mast cell stabilizers and a short course of topical steroids produced dramatic resolution of the lesion. Biopsy of the erythematous conjunctiva adjacent to the area of corneal inflammation showed the presence of mast cells. CONCLUSION: This is the first case of corneal inflammatory infiltration in a patient with mastocytosis. Therapy for this condition consists of a combination of topical mast cell stabilizers, topical steroids, and systemic antihistaminic therapy.

Tetany, malabsorption, and mastocytosis.

Mastocytosis is characterized by increased proliferation of mast cells. Two patients had systemic mastocytosis involving the skin and gastrointestinal tract, complicated by malabsorption and tetany. Absorption studies in these patients suggested that the entire small bowel was involved and that the defect was mild in the absence of diarrhea. Small bowel biopsies disclosed infiltration of the lamina propria and submucosa by mast cells, and gastrointestinal tract x-ray films showed nodular densities, edema, and thickening of the bowel wall. Tetany was due in part to combined hypocalcemia, hypomagnesemia, and hypokalemia. Diarrhea and malabsorption were due to mast cell infiltration of the bowel rather than to histamine. patients with signs of systemic mastocytosis should have careful evaluations and be followed up to prevent development of malabsorption and tetany.