Severe Reactions, Immunodermatology & Skin Cancer

Urticaria and Angioedema: Quieting the Mast Cell

Hives look like a trivial problem — itchy welts that come and go — until you meet the patient who has scratched through eighteen months of sleepless nights, or the one whose lips and tongue swell so fast they can barely breathe. Behind both sits one cell: the mast cell, a bag of pre-formed histamine waiting for a trigger to spill. Almost the entire treatment story is the story of quieting that cell — blocking the histamine it releases, and, when antihistamines fail, switching off the cell itself. But there is a trap. Some deep swellings are not driven by histamine at all, and pouring on antihistamines and steroids does nothing while the airway closes. Knowing which swelling is which is the whole game.

Immunobullous Disease and Cutaneous Lupus: Autoantibodies Against the Skin

Most skin disease is a story of inflammation gone astray. This chapter is stranger: here the immune system builds antibodies against the skin's own scaffolding — the molecular rivets that hold one skin cell to the next, or the anchors that fasten the epidermis to the tissue beneath. Undo those rivets and the skin quite literally comes apart, blistering at a touch. The drugs that save these patients are not creams but the heavy machinery of immunosuppression: corticosteroids to gain control, steroid-sparing agents to hold it, and B-cell depletion to switch off the antibody factory itself. Learning them means learning the safety rituals — the G6PD test, the retinal exam, the infection screen — that make powerful immunosuppression survivable.

Severe Cutaneous Drug Reactions: SJS/TEN and DRESS

Most rashes a drug causes are a nuisance — a pink, itchy blush that fades when the prescription ends. But a small handful are among the most feared emergencies in all of medicine, and their cause is not an infection or a cancer: it is a pill the patient was told to take. In these reactions the immune system, provoked by the drug, turns on the skin itself — peeling it away in sheets, or setting fire to liver, kidney and marrow at once. The single most important treatment is not a fancy antidote. It is to recognise the culprit and stop it. This is the pharmacovigilance chapter of dermatology: where the drug is the disease.

Skin Cancer and Photoprotection: From Sunscreen to Field Therapy

Most cancers are things that happen inside the body, out of sight. Skin cancer is different — it is written on the surface, in decades of sunlight, and much of its story is one of prevention and topical chemistry rather than the operating theatre. This chapter is about that pharmacology: how a sunscreen actually stops a photon, how a cream can wipe out a whole field of pre-cancerous cells while sparing the normal ones, and where dermatology finally hands the invasive tumours over to targeted therapy and immunotherapy.