Flushing and increase of serum tryptase after mechanical irritation of a solitary mastocytoma

Solitary mastocytomas are infiltrates of mast cells in the upper corium, appearing at any side of the body as brownish-reddish plaques in the first months of life. Their course is benign with a spontaneous regression in most cases. A 5-month-old boy presented a 5 x 3 cm sized brownish-yellow plaque on the back of his right hand. His parents reported repeated episodes of swelling and blistering of the skin lesion as well as recurrent systemic flush-reactions. General laboratory parameters were without pathological findings including a normal serum tryptase (5.5 microg/L). A few minutes after rubbing, the lesion became urticarially swollen and the infant developed a general flush reaction accompanied by a bilateral miosis and asthma-like symptoms which disappeared completely after oral administration of 7 drops of dimentinden. Assessment of the serum tryptase two hours after the provocation revealed a more than 5-fold increase (29.3 microg/L) compared to the basic value. We conclude that uncontrolled stroking of mastocytomas should be avoided in patients with a systemic reaction in their history, since this case demonstrates that despite its limited size, mechanical irritation of a solitary mastocytoma may induce strong systemic symptoms as witnessed by transient increase of the serum tryptase, which to our knowledge has not been described in the literature before.