Cutaneous mastocytosis
Cutaneous mastocytosis is a group of disorders of excessive mast cell accumulation confined to the skin, most often presenting in infancy as maculopapular cutaneous mastocytosis/urticaria pigmentosa, a solitary mastocytoma, or diffuse cutaneous disease. First-line management is trigger avoidance plus oral H1 antihistamines for pruritus and flushing, with H2 antihistamines or cromolyn added for gastrointestinal symptoms and self-injectable epinephrine kept on hand for anaphylaxis.
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What this article covers
- Overview
Cutaneous mastocytosis (CM) is a group of disorders of pathologic mast cell accumulation confined to the skin, with three World Health Organization-recognized variants: maculopapular cutaneous…
- Epidemiology
Mastocytosis in all its forms is rare, with an overall estimated prevalence of about 1 per 10,000 persons.
- Risk factors
No major environmental risk factor has been identified; most cases are sporadic, though rare familial clustering has been reported.
- Pathophysiology
Activating KIT mutations promote clonal expansion and impaired apoptosis of mast cells, though the pathogenesis of pediatric-onset disease may differ in important ways from adult disease.
- Clinical features
Maculopapular cutaneous mastocytosis/urticaria pigmentosa (MPCM/UP), the most common pediatric variant, presents as yellow-tan to reddish-brown macules or slightly raised papules, most often on the…
- Differential diagnosis
Epidermolysis bullosa simplex: skin fragility and blistering after minor trauma, confirmed by immunofluorescence of a fresh blister biopsy, rather than the Darier's-sign-positive infiltrated lesions of mastocytosis.
- Diagnosis
The diagnosis of cutaneous mastocytosis requires the major criterion, characteristic skin lesions of MPCM/UP, mastocytoma, or DCM, plus at least one of two minor criteria on skin biopsy (increased…
- Management
First, counsel avoidance of mast cell degranulation triggers, including heat, friction, sudden temperature change, emotional stress, and deliberate irritation of mastocytoma or DCM lesions, and…
- Complications
Recurrent anaphylaxis, more likely with extensive skin involvement or an elevated baseline tryptase.
- Prognosis
Onset within the first 2 years of life carries an excellent prognosis: over 80 percent of children with cutaneous mastocytosis experience spontaneous resolution, most before puberty.
- Prevention
Avoid mast cell-activating medications when possible, including opioids, NSAIDs, iodinated contrast agents, and vancomycin, unless the patient's tolerance for a specific agent is already established.
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