A 5 yr. old male child has multiple hyperpigmented macules over the trunk. On rubbing the lesion with rounded end of pen, he developed urticarial wheal, confined to border of lesion, most likely diagnosis is:

Ans. C. Urticaria pigmentosa* It is urticaria pigmentosa.* It is cutaneous mastocytosis presenting with pigmented lesions.* On rubbing the lesions mast cells degranulate releasing histamine.* This produces the wheal and flare of the lesion. It is known as Darier's sign.Epidermal acantholysis in mid epidermis with "dilapidated or crumbling brick wall" appearance. Darier's disease is associated with ATP2A2 defect