Types of Dermatitis

"Dermatitis" is an umbrella. Knowing which type sits under it changes the trigger hunt, the treatment and the outlook.

The main types

• Atopic dermatitis: the inherited eczema - begins in childhood, lives in the flexures, travels with asthma and allergic rhinitis; a lifelong tendency with calm stretches and flares
• Irritant contact dermatitis: direct chemical damage - soaps, detergents, wet work; hands of homemakers, cleaners, healthcare workers, mechanics
• Allergic contact dermatitis: a specific immune allergy - nickel, fragrances, hair dye, rubber, cement; appears where the allergen touched, patch testing identifies the culprit
• Seborrheic dermatitis: greasy yellow scale on the scalp (its mild form is dandruff), eyebrows, sides of the nose, behind ears; linked to a normal skin yeast (Malassezia), worse in winter and stress
• Stasis dermatitis: on lower legs with varicose veins and swelling - pooling blood inflames the skin; brown staining, risk of ulcers
• Nummular dermatitis: stubborn coin-shaped itchy patches on the limbs, often after dry skin or minor injury

Types people confuse it with

• Psoriasis: well-defined thick silvery plaques, less itch - a different disease
• Fungal infection (ringworm): ring-shaped with an active edge - contagious, unlike dermatitis; a skin scraping settles it
• Scabies: night-predominant itch with burrows, affecting family members - contagious

One-line summary

The dermatitis family - atopic, irritant contact, allergic contact, seborrheic, stasis and nummular - is separated by where the rash sits and what triggers it, and separated from psoriasis, ringworm and scabies by a doctor's eye and simple tests.