Abstract: A 5-month-old male child presented with recurrent erythema and blisters on the right lower extremity since he was born. Physical examination showed brown plaques on the right lower limb with orange peel like surface, blisters on the right side of the lesion with positive of Darier sign. Biopsy showed the epidermal hyperkeratosis, the spinous layer thickening, and infiltration of large number of mast cells in the superficial and middle dermis. Based on the clinical history, clinical features and histopathological features, the diagnosis of cutaneous mastocytosis characterized by mastocytoma was made. The patient was given no treatment and is under follow-up. 

Key words: mastocytosis, cutaneous, children, skin tumor