Urticaria and Angioedema in Patients with Darker Skin

00:01 Welcome to our lecture on drug-induced urticaria and Angioedema.

00:08 Weals or hives or urticaria is caused by the release of histamine and other vasoactive substances. Angioedema is involvement of the deeper layers of the skin, which can additionally involve the eyes, the mouth, and the larynx. Urticaria and angioedema are one of the most common drug-induced skin eruptions, second only to Morbilliform eruption, which we've just spoken about.

00:36 9% of all urticarias are usually drug-induced .

00:41 Chronic drug-induced urticaria is rare in children.

00:47 Urticaria and angioedema can be due to immune and non-immune mechanisms.

00:52 The immune mechanisms include type I or type III, immune complex-mediated hypersensitivity reactions, and the non-immune mechanisms.

01:01 Here what happens is that drug directly stimulates mast cells to release inflammatory mediators. The following are the common drugs that cause angioneurotic edema and urticaria . Clinical manifestations of drug induced urticaria, one sees reactions that are similar to non-drug-related urticaria.

01:27 It usually begins as an intense, pleuritic, circumscribed, raised, and erythematous eruption, often with central pallor.

01:36 In black patients, you may not see the erythematous hue, but rather skin colored or dusky or lichenoid hue.

01:45 Lesions can enlarge, coalesce with other lesions, and typically disappear over a couple of few hours.

01:53 It can affect any site of the body, but tends to be widely distributed, and the trunk is the most commonly affected location.

02:03 What about drug-induced angioedema? This is swelling of the deeper dermis and subcutaneous tissues, and it involves the eyes, lips, mouth and the larynx as you can see on this picture. It may co-exist with urticaria in as many as 50% of cases.

02:22 Now let's talk about the complications of urticaria and or angioneurotic edema.

02:29 Angioedema involving the face can be life threatening.

02:33 It may involve tongue swelling and laryngeal edema, which can lead to airway obstruction.

02:44 Anaphylactic reaction: this is the drugs are second most common cause of anaphylactic reaction.

02:58 How do we make a diagnosis as a clinical history and physical examination? We also do prick testing oral provocation tests were indicated.

03:09 Other investigations may include doing full blood count, complement and leukocyte histamine release, etc.

03:19 one of the differential diagnosis of urticaria is that urticarial vasculitis.

03:25 Urticarial vasculitis: the lesions last for more than 24 hours, leaving residual hyperpigmentation, which is pretty more obvious in patients with skin of color. Erythema multiforme is also a differential, where one sees target like bull's eye lesions characterized by concentric rings of erythema with central clearing.

03:49 Morbilliform drug eruption is also a differential for this condition.

03:55 The management involves identifying and stopping the causative drug.

04:03 Non-essential medications should also be avoided.

04:09 The second-generation antihistamines can also be used, and depending on the severity, a short course of corticosteroids may be indicated.