Darier's sign

Darier's sign is a change observed after stroking lesions on the skin of a person with systemic mastocytosis or urticaria pigmentosa.

[1] In general, the skin becomes swollen, itchy and red.

This is a result of compression of mast cells, which are hyperactive in these diseases.

These mast cells release inflammatory granules which contain histamine.

[2][3] This dermatology article is a stub.

Stroking the skin leads to a localised subcutaneous anaphylactoid reaction with mast cell degranulation and urticarial rash.