Case Report
A 46-year-old woman presented with a rash that had been present for more than 20 years but had progressed over the past 6 years and was associated with pruritus, burning, and blistering precipitated by temperature changes or anxiety. In addition, she had watery diarrhea for 5 years and also had been found to have osteopenia. She was a healthy-appearing woman with prominent facial erythema. Vital signs were normal. Skin examination revealed facial telangiectases as well as erythema and 2- to 4-mm reddish brown papules and macules on the extensor surfaces of the arms and thighs, chest, abdomen, and back, coalescing into plaques on the thighs (Figure). She had bilateral axillary lymphadenopathy. Liver and spleen were not palpable. Her hemoglobin level was 12.7 g/dL (reference range, 14.0–17.5 g/dL); white blood cell count was 5.2X109/L (reference range, 4.5–11.0X109/L) with 63 neutrophils, 36 lymphocytes, and 1 monocyte; and platelet count was 301X109/L (reference range, 150–350X109/L). Chemistries were within reference range, except for an alkaline phosphatase level of 136 U/L (reference range, 38–126 U/L). Biopsy of a forearm skin lesion showed an unremarkable epidermal layer overlying a dermis without vasculitis but with a mild increase in perivascular and focally interstitial mononuclear cells staining with mast cell tryptase and CD117. Serum tryptase level was greater than 200 ng/mL (reference,
Article
Systemic Mastocytosis: Classification, Pathogenesis, Diagnosis, and Treatment
Mastocytosis is a heterogeneous entity that may present as either a cutaneous or systemic disease. Progression of pediatric cutaneous mastocytosis (CM) is uncommon, but in adults, this condition persists and often progresses to systemic disease. Mast cell proliferation and differentiation from stem cell precursors depend on a number of factors, including a mast cell tyrosine kinase receptor (kit) and its ligand (the stromal cell–derived cytokine stem cell factor). A gain-of-function mutation in codon 816 of c-kit is frequently present in mast cells of patients with systemic mastocytosis (SM). The diagnostic approach for a patient with suspected mast cell disease includes a thorough skin examination, a skin biopsy, a serum tryptase level, and bone marrow aspiration and biopsy. The treatment is directed toward avoidance of triggers of mast cell mediator release and management of symptoms. Aggressive cases are managed with cytoreductive therapies, such as interferon alfa-2b and cladribine. Research has been directed at more specific treatment modalities, including specific kit tyrosine kinase inhibitors.