Skin Biopsy in Chronic Urticaria: When and Where and What to Look for?

Chronic urticaria is a relatively common condition in dermatology and is usually diagnosed on clinical grounds. Skin biopsy, however, may be indicated in certain cases to confirm diagnosis and rule out other conditions that can cause hive-like rashes. We review histopathologic findings seen in both chronic urticaria and other entities in the differential diagnosis. We then propose an algorithm of indications for skin biopsy in patients with hive-like rashes and suggest possible diagnoses based on the histopathologic findings.