Cutaneous mastocytosis with abundant eosinophilic infiltration: a case report with review of the literature.

Mastocytosis is a clonal proliferation of mast cells that accumulates in one or more organs [1]. This disorder is heterogenous, ranging from skin lesion that may spontaneously regress to multiple organ lesions that show a highly aggressive course, and a recent World Health Organization Classification divides it into 7 subtypes: cutaneous mastocytosis, indolent systemic mastocytosis, systemic mastocytosis with associated clonal hematological nonmast-cell lineage disease, aggressive systemic mastocytosis, mast cell leukemia, mast cell sarcoma, and extracutaneous mastocytoma [1]. Cutaneous mastocytosis, also referred to as urticarial pigmentosa, is the most common subtype of mastocytosis, which shows mast cell infiltration confined to the skin [1]. Cutaneous mastocytosis is histopathologically characterized by aggregates of mast cells filling the papillary dermis and extending as sheets and aggregates into the reticular dermis [1]. Eosinophilic infiltration is an uncommon finding of cutaneous mastocytosis, and only limited cases of cutaneous mastocytosis with abundant eosinophilic infiltration have been reported in the English literature [2-4]. Herein, we describe an additional case of cutaneous mastocytosis with abundant eosinophilic infiltration and discuss the clinicopathological features and differential diagnostic considerations.