Chillblains

• Inflamed and painful purple-pink swellings on the fingers, toes or ears that appear in response to cold.
• Result from an overcompensatory cold-induced vasoconstriction of cutaneous arterioles and venules.
• Usually affect women.
• Rx = Warm housing and clothing. Nifedipine may help.

Erythema ab igne

A reticulate, pigmented erythema.

Due to heat-induced damage - sitting before a fire, hot water bottles.

Livedo reticularis

- Marble-patterned cyanosis of the skin.

- Due to reduced arteriolar flow.

- Usually in women.

Causes:

• Physiological, i.e. cold-induced. Revesible.
• Vasculitis, e.g. SLE, PAN.
• Hyperviscosity due to cryoglobulinaemia or polycythaemia.
• Sneddon syndrome - livedo reticularis with cerebrovascular disease and circulating antiphosphlipid antibodies.

Treatment is aimed at the underlying disease.

Koebner phenomenon

Source = Wikipedia

Koebner phenomenon = skin lesions appearing on lines of trauma. It may result from either linear exposure or linear irritation.

Linear exposure:

• Molluscum contagiosum (auto-inoculation)
• Warts (auto-inoculation)
• Toxicodendron dermatitis (e.g. poison ivy... linear from brushing against plant).

Linear irritation, e.g. scratching or surgical wound:

• Psoriasis*
• Eczema*
• Lichen planus*
• Vitiligo*
• Lichen nitidus
• Lichen sclerosus
• Pityriasis rubra pilaris
• Keratosis follicularis
• Elastosis perforans serpiginosa.

*4 most common causes of Koebner phenomenon = PELV

The Koebner phenomenon was named after a rather eccentric, renowned German dermatologist, Heinrich Koebner (1838–1904). Koebner is best known for his work in mycology. Here is one story to illustrate his intense nature: in a medical meeting he proudly exhibited on his arms and chest three different fungus infections, which he self-inoculated in order to prove the infectiousness of the organisms he was studying.

Blisters in neonates = PESIsa

Causes of blisters in neonates:

• Pemphigus neonatorum (impetigo).
• Epidermolysis bullosa.
• Staphylococcal scalding skin syndrome.
• Incontinentia pigmenti.

Strata of the epidermis

From superficial to deep = Chris Lee gives second base

Corneum

Lucidum

Granulosum

Spinosum

Basale

Blistering disorders - DIFIŻA

Causes of blistering disorders:

• Drugs (ACE-i, furosemide).
• Infection e.g. herpes.
• Friction/trauma
• Insect bites
• Zinc deficiency
• Automimmune e.g. pemphigus, pemphigoid.