Analysis and long-range follow-up data are given for 112 patients with urticaria pigmentosa, studied regarding the characteristics and natural course of the disease. The cases were classified readily into 3 major groups (I, solitary lesion, 12 cases; II, multiple lesions appearing in infancy or early childhood, 72 cases; III, multiple lesions appearing post-childhood, 28 cases). These groups were distinguished by age of onset, many other clinical differences, and eventual outcome.
Among the 24 variables studied the genetic inquiry did not answer the question of etiology, but disclosed an instance of involvement of mother and daughter. A significantly higher number of patients with urticaria pigmentosa were found to have positive histories of hay fever or asthma in themselves or their close relatives.
Neither biopsy nor urtication of lesions on demand are infallible diagnostic tests but must be considered along with morphologic features. Vesiculation was present at some time during the course of at least half of those patients with onset early in life, while the postchildhood group was characterized by complete absence of vesiculation. When present, it always declined gradually, averaging 2 years. Dermographism was encountered in excess of half the patients with multiple lesions, testifying to the generalized cutaneous increase of tissue mast cells. At least 5 patients among the 3 groups experienced generalized flushing.
Eventual outcome of cutaneous lesions varied according to type of case. Group I cases improved spontaneously in a few years, and excision is seldom necessary. Group II cases also improved greatly in all clinical regards when sufficient time passed; about half cleared entirely by adolescence and the remainder continued to have lightly pigmented asymptomatic macular lesions. Group III cases regularly had persistence and symptomatic activity of the lesions indefinitely, and 5 of them had systemic mast cell involvement. No therapeutic efforts seemed to affect the course of the disease, but available measures could often relieve symptoms.