Cutaneous mastocytosis

Fig. 1. Typical MPCM (urticaria pigmentosa) is the most common form of cutaneous mastocytosis, a In adults, lesions consist of numerous small red-brown macules and slightly elevated disseminated papules, b In less obvious cases, however, lesions arefewor less well recognizable and may be overlooked. 

Mastocytomas and diffuse cutaneous mastocytosis are further manifestations of cutaneous mastocytosis (CM) [9]. Solitary mastocytomas are common in children. Most are present at birth or develop in infancy. These lesions are flat or mildly elevated, well demarcated, solitary yellowish red-brown plaques or nodules, typically 2-5 cm in diameter. Diffuse cutaneous mastocytosis is a rare disorder characterized by diffuse mast cell infiltration of large areas of the skin that presents in infants in the first year of life. Severe edema and leathery indurations of the skin leads to accentuation of skin folds (pseudo-lichenified skin) and a peau-dbrange-like appearance. Systemic complications include hypotension and gastrointestinal hemorrhage. Infants and young children with considerable mast cell infiltration of the skin sometimes exhibit blister formation in the first 3 years of life. MPCM and other forms of CM have been classified in a consensus nomenclature (table 1) [10]. 

Maculopapular cutaneous mastocytosis/urticaria pigmentosa Subvariants... 

Altered metabolism of mast-cell growth factor (c-kit ligand) in cutaneous mastocytosis. N Engl J Med 1993 328 1302-1307. 

Whereas in children internal organ involvement (systemic mastocytosis, SM) is unusual, MPCM in adults is associated with SM in the majority of cases [10]. WHO criteria for SM consist of the major criterion of multifocal mast cell infiltrates in the bone marrow or other extracutaneous organ(s) and four minor criteria (table 2) [21] 25% or more of mast cells in non-cutaneous biopsy sections with spindle-shaped or abnormal morphology, or... 

Table 1. Classification of cutaneous forms of mastocytosis [adapted from 10]... 

Mastocytosis is recognized in most patients because of the presence of characteristic cutaneous lesions [10]. A positive Darier s sign and/or histological examination of the skin using metachromatic stains, or by immunohistochemistry using antibodies to mast cell tryptase, helps confirm the diagnosis of cutaneous disease. 

Brockow K, Akin C, Huber M. Metcalfe D Assessment of the extent of cutaneous involvement in children and adults with mastocytosis relationship to symptomatology, tryptase levels, and bone marrow pathology J Am Acad Dermatol 2003 48 508-516. 

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