History: This lesion was present at birth.It had thickened slightly since and had developed vesicles and a blister on the surface when rubbed.Clinically it was a cutaneous mastocytoma.These lesions are localised collections of mast cells which release histamine and other chemicals from the mast cells when they are traumatised or because of drugs such as aspirin or foods such as chocolate,shellfish or strawberries.They may be single or multiple but usually resolve on their own by puberty.