Regression of urticaria pigmentosa in adult patients with systemic mastocytosis: correlation with clinical patterns of disease.

OBJECTIVE

To determine clinical correlates of urticaria pigmentosa (UP) regression in adult patients with systemic mastocytosis (SM).

DESIGN

Cohort study of the natural history of mastocytosis.

SETTING

National Institutes of Health Clinical Center.

PATIENTS: In a study of adult patients referred to the National Institutes of Health after 1980 and observed for a minimum of 10 years, 12 of 106 adult patients experienced clearance or fading of UP.

MAIN OUTCOME MEASURES: Data from each patient's history and results of physical examination, laboratory evaluation, and organ biopsy at presentation to the National Institutes of Health were compared with findings at the patient's most recent visit.

RESULTS

In the patients in whom clearance of (n = 5) or a decrease in skin lesions (n = 7) was noted, UP had persisted from 4 to 34 years (median, 17 years). Older age was a prognostic feature for regression of UP. Despite improvement of UP, the 2 patients with SM with an associated hematologic disorder experienced a deterioration in clinical condition. In the 10 patients with indolent SM, severity and frequency of symptoms decreased as the UP regressed. However, bone marrow changes consistent with SM remained.

CONCLUSIONS

Urticaria pigmentosa regresses in approximately 10% of the older patients who have SM. In patients with an associated hematologic disorder such as myelodysplasia, this regression may be accompanied by disease progression. In contrast, regression of UP in patients with indolent SM parallels a decrease in disease intensity, although bone marrow findings of indolent SM remain.