What is the prognosis of mastocytosis?

Updated: Jun 07, 2018
  • Author: Jacquiline Habashy, DO, MSc; Chief Editor: Dirk M Elston, MD  more...
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The prognosis depends on the age of onset. Most patients with urticaria pigmentosa (UP) exhibit onset before age 2 years, which is associated with an excellent prognosis, often with resolution by puberty. The number of lesions diminishes by approximately 10% per year. However, acute extensive degranulation rarely can cause life-threatening episodes of shock.

Increased serum baseline tryptase levels and extensive skin involvement are predictors for the severity of mast cell activation episodes in children with mastocytosis. Serum baseline total tryptase to predict the need for daily antimediator therapy, hospitalization, and episodic management in an ICU were 6.6, 15.5, and 30.8 μg/L, respectively. [17]

Slight improvement of skin symptoms, reflected by decrease of SCORing MAstocytosis Index, with decline in serum tryptase levels is the typical course in patients with diffuse cutaneous mastocytosis. [18] Systemic mastocytosis may occur more frequently in diffuse cutaneous mastocytosis patients. [19] Patients with adult or adolescent-onset urticaria pigmentosa are more likely to have persistent disease and are at greater risk for systemic involvement. Juvenile-onset systemic mastocytosis has a malignant transformation rate as high as 7%, whereas adult-onset systemic mastocytosis has a malignant transformation rate as high as 30%. [20]

Rarely, mast cell leukemia may develop in young adults with persistent maculopapular cutaneous mastocytosis. [21]

Primary cutaneous mast cell sarcoma due to the transformation of a benign solitary mastocytoma in an adult has been reported. [22]

Cutaneous mastocytosis onset after age 10 years portends a poorer prognosis, because late-onset disease tends to be persistent, is associated more often with systemic disease, and carries a higher risk of malignant transformation.

In patients with systemic mastocytosis, regression of urticaria pigmentosa is associated with a decreased frequency and severity of other symptoms. Bone marrow findings do not change with regression of urticaria pigmentosa.

One study shows that anaphylaxis is common in patients with mastocytosis (4.3-5.5% per year disease duration) and appears higher than in the healthy population. In childhood, the risk of anaphylactic episodes has been shown to be limited to those with extensive blistering skin disease, but nonexistent for children with mastocytoma or limited disease. In adults, anaphylactic episodes generally appear to be more severe in patients with extensive systemic disease. [23]

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