499 Mastocytosis: Importance as Differential Diagnosis in Skin Diseases. Report of Two Cases

BACKGROUND: Is a heterogeneous disorder characterized by clonal proliferation of mast cells (MCs) leading accumulation in different organs. Pathologic activation of KIT due to a mutation in codon 816 replacing aspartic acid for valine: KIT-D816V (>93%) has been identified. Cutaneous Mastocytosis (CM), Classified in Urticaria Pigmentosa (UP), solitary mastocytoma, diffuse, and telangiectasia macularis eruptiva perstans (TMEP). The most common is the Urticaria Pigmentosa as fixed, reddish brown macular or papular, urticate in physical irritation (Darier's sign). WHO Diagnostic Criteria for cutaneous Mastocytosis: Presence of at least 1 of skin lesions with Focal dense MC infiltrates (>15 MCs per cluster) or diffuse (>20 cells per high-power field). METHODS: We report 2 cases of patients with this disease who were not diagnosed at first. A 51 years old female, who noticed 20 years ago, the appareance of itchy "spots” in thorax, abdomen and extremities, progressively increasing in number and size, receiving unspecified treatments without improvement. On examination, we found brown macules with sharp borders, 0.3 to 0.5 cm erythema and Darier´s sign, disseminated lesions on thorax, shoulders and extremities. A 45 year old female, who noticed 2 years ago, the appareance of freckles in neck, arms, thorax and legs progressively increasing in number, who in stress are itchy. Receiving multiple treatments without improvement. On examination disseminated brown macules with sharp borders <0.5 cm with Darier´s sign. RESULTS: In both patients, the biopsies taken had findings compatible with mastocytosis (inflammatory infiltrate with perivascular lymphocytes, histiocytes and mast cells). Mast cells were not quantified. We realized a genetic study in search of c-kit mutation. Once the diagnosis was considered and treated accordingly, they had a good control of symptoms. CONCLUSIONS: Mastocytosis is diagnosed by clinical features and histological infiltrate of mast cells. The skin is the organ most frequently affected. These patients previously received multiple treatments with no clinical improvement suggest inadecuate diagnosis. Histologically, compatible although no quantificate mast cells, but a mutation of c-kit was found. It is important to consider this disease in the differential diagnosis of pruritic skin disorders since an appropriate treatment with an improvement in quality of life also must be aware of the risk of anafylaxis and its potential triggers.