ICD-9 : 757.33/202.6 • ICD-10 : Q82.2
Between birth and 2 years of age (55%) (NCM, PPCM, UP), but mastocytosis can occur at any age; infancy-onset mastocytosis rarely associated with systemic mastocytosis.
Slight male: female predominance.
Human mast cell proliferation depends on Kit ligand and Kit is the receptor for stem cell factor. c-kit mutations have been identified in blood and tissues of patients with mastocytosis. Mast cells contain several pharmacologically active substances that are associated with the clinical findings in mastocytosis: histamine (urticaria, GI symptoms), prostaglandin D2 (flush, cardiovascular symptoms, bronchoconstriction, GI symptoms), heparin (bleeding into tissue, osteoporosis), neutral protease/acid hydrolases (patchy hepatic fibrosis, bone lesions).
Stroking lesion causes it to itch and to wheal (Darier sign). Various drugs are capable of causing mast cell degranulation and release of pharmacologically active substances that exacerbate skin lesions (whealing, itching) and cause flushing: alcohol, dextran, polymyxin B, morphine, codeine, scopolamine, D-tubocuratin, nonsteroidal anti-inflammatory drugs. Flushing episode can also be elicited by heat or cold and may be accompanied by headache, nausea, vomiting, diarrhea, dyspnea/wheezing, syncope. Systemic involvement may lead to symptoms of malabsorption; portal hypertension. Bone pain. Neuropsychiatric symptoms (malaise, irritability).
Macular to papular to nodular lesions (mastocytoma) (Fig. 19-17), often solitary; may be multiple, but few. Yellow to tan-pink, which become erythematous and raised (urticate) when stroked due to degranulation of mast cells (Darier sign); in some patients, lesions become bullous.
Mastocytosis: solitary mastocytoma (NCM) A solitary, tan plaque with poorly demarcated borders on the hand of an infant. When stroked very vigorously, the lesion became red, more elevated and a blister developed.
Tan, occasionally yellowish plaques, up to 2–5 cm, sharply defined with irregular outlines. Darier sign positive (Fig. 19-18). No scaling, occasionally with bulla formation after rubbing. Occurs mostly in infants and children.
Mastocytosis: generalized (PPCM) Multiple, flat-topped papules and small plaques of brownish to yellowish color on the buttocks of a child. Lesions are asymptomatic. Rubbing one of the lesions has resulted in urtication and an axon flare, a positive Darier sign, and itching.
Tan macules to slightly raised tan to brown papules (Fig. 19-19). Disseminated, few or >100 with widespread symmetric distribution. Darier sign (whealing) after rubbing; in infants may become bullous. Occurs in infancy and/or de novo in adults. Bright red diffuse flushing occurring spontaneously, after rubbing of skin, or after ingestion of alcohol or mast cell–degranulating agents.
Mastocytosis: urticaria pigmentosa (UP)A. Multiple, generalized tan to brown papules in a child. The patient had occasional syncopes, diarrhea, and wheezing; workup revealed systemic mastocytosis. B. Brown papules on the forehead of a 3-year-old boy who was otherwise asymptomatic.
Freckle-like, brownish to reddish macules (Fig. 19-20) with fine telangiectasia in long-standing lesions. Hundreds of lesions, trunk > extremities; lesions may be confluent. Urticate with gentle stroking. Dermatographism. Occur only in adults and very rare.
Mastocytosis: telangiectasia macularis eruptiva perstans Small, stellate erythematous macules and telangiectases on the back of a 45-year-old woman who had systemic (indolent) mastocytosis.
Yellowish, thickened appearance of large areas of skin; “doughy.” Smooth with scattered elevation, resembling leather, “pseudoxanthomatous mastocytosis,” skin folds exaggerated, especially in axilla/groin. Large bullae may occur after trauma or spontaneously. DCM may present as erythroderma (Fig. 19-21). Very rare, occurs at all ages.
Mastocytosis: diffuse cutaneous mastocytosis The skin of this infant is uniformly erythematous (erythroderma) secondary to infiltrating mast cells with several spared, white areas of normal skin. In this child there were systemic symptoms associated with the flare of this erythroderma: syncope, wheezing, and diarrhea.
Flushing, accompanied by wheezing, headache, asthma, nausea, vomiting, diarrhea, syncope. Bone pain/spontaneous fractures with osteolytic lesions. Neuropsychiatric symptoms, malaise, irritability. Malabsorption, weight loss.
Accumulation of normal-looking mast cells in dermis. Mast cell infiltrates may be sparse (spindle-shaped) or densely aggregated (cuboidal shape) and have a perivascular or nodular distribution. Pigmentation due to increased melanin in basal layer.
Systemic mastocytosis: anemia, leukocytosis, eosinophilia.
Tryptase levels↑, coagulation parameters.
Patients with extensive cutaneous involvement may have increased 24-h urinary histamine excretion.
Define bone involvement (lytic bone lesions, osteoporosis, or osteosclerosis), and endoscopy for small-bowel involvement.
Smear and/or biopsy for morphology and mast cell markers.
Clinical suspicion, positive Darier sign, confirmed by skin biopsy.
Juvenile xanthogranuloma, Spitz nevus.
Langerhans cell histiocytosis, secondary syphilis, papular sarcoid, generalized eruptive histiocytoma, non-Langerhans cell histiocytosis of childhood.
Cutaneous T cell lymphoma, pseudo-xanthoma elasticum, forms of erythroderma.
Most cases of solitary mastocytosis and generalized UP and PPCM in children resolve spontaneously. They rarely have systemic involvement. Adults with onset of UP or TMEP with extensive cutaneous involvement have a higher risk for development of systemic mastocytosis (see Table 19-3). In young children, acute and extensive degranulation may be life-threatening (shock).
Avoidance of drugs that may cause mast cell degranulation and histamine release (see above).
Antihistamines, both H1 and H2, either alone or with ketotifen. Disodium cromoglycate, 200 mg four times a day, may ameliorate pruritus, flushing, diarrhea, abdominal pain, and disorders of cognitive function but not skin lesions. PUVA treatment is effective for disseminated skin lesions, but recurrence is common. Vascular collapse is treated with epinephrine. NCM responds to potent glucocorticoid ointments under occlusion or to intralesional triamcinolone acetonide but may eventually recur.