Psoriasis & Chronic Dermatitis

Psoriasis is an immune disease that shows on the skin. "Psoriasis is a chronic (long-lasting) disease in which the immune system becomes overactive, causing skin cells to multiply too quickly. Patches of skin become scaly and inflamed, most often on the scalp, elbows, or knees, but other parts of the body can be affected as well." The mechanism: "The pathophysiology of psoriasis involves infiltration of the skin by activated T cells which stimulate the proliferation of keratinocytes. This dysregulation in keratinocyte turnover results in the formation of thick plaques." The scale has its own cause — "the epidermal cells fail to secrete lipids which results in flaky and scaly skin, which is typical of psoriasis." Epidermal hyperplasia is part of the picture (see the cellular adaptation page for the term).

Genes load it, the environment triggers it. "Scientists do not fully understand what causes psoriasis, but they know that it involves a mix of genetics and environmental factors," and "Many people with psoriasis have a family history of the disease." It runs in cycles: "The symptoms of psoriasis can sometimes go through cycles, flaring for a few weeks or months followed by periods when they subside or go into remission." There is no cure — "While there is currently no cure for psoriasis, there are treatments that keep symptoms under control" — and, the teaching point that matters most for body image, "Psoriasis is not contagious so you cannot catch it or spread it."

Injury to the skin makes new plaques. "Any injury to the skin in patients with psoriasis in the form of either mechanical, chemical, or radiational trauma induces lesions of psoriasis at that site which is called the Koebner phenomenon." Lift the scale off a plaque and the capillaries show: "On successive removal of psoriatic scales pinpoint bleeding points are seen. This is called the Auspitz sign." Certain drugs make it worse — "Certain drugs like chloroquine, lithium, beta-blockers, steroids, and NSAIDs can worsen psoriasis." — so every new prescription is a trigger check.

Plaque psoriasis is the common one. "This is the most common kind, and it appears as raised, red patches of skin that are covered by silvery-white scales. The patches usually develop in a symmetrical pattern on the body and tend to appear on the scalp, trunk, and limbs, especially the elbows and knees." It "affects 85% to 90% of patients." On brown or black skin, the NHS notes, patches can look "grey on brown or black skin, and cause dark marks on the skin after the psoriasis has gone." Nails pit and thicken — "Thick, ridged, pitted nails." Guttate "usually appears in children or young adults, and looks like small, red dots, typically on the torso or limbs. Outbreaks are often triggered by an upper respiratory tract infection, such as strep throat." Inverse "appears as smooth, red patches in folds of skin, such as beneath the breasts or in the groin or armpits. Rubbing and sweating can make it worse."

Pustular psoriasis — "pus-filled bumps called pustules surrounded by red skin appear. It usually affects the hands and feet, but there is a form that covers most of the body." The pustules are sterile: "Pustular psoriasis presents with small non-infectious pus-filled lesions with erythema surrounding it," and "Generalized pustular psoriasis is associated with hypocalcemia and presents with sterile pustules on an erythematous plaque involving the whole body."

Erythrodermic psoriasis "is a rare but severe form of psoriasis characterized by red, scaly skin over most of the body. It can be triggered by a bad sunburn or taking certain medications, such as corticosteroids." StatPearls names the classic trigger: "It is the result of an exacerbation of unstable plaque psoriasis, following the abrupt withdrawal of systemic steroids." The skin can no longer do its job: "Complications of erythroderma include impairment in barrier functions of the skin, disturbance in basal metabolic rate, and increased cutaneous circulation in turn affecting the heart with cardiac failure." The rule to remember: "Pustular psoriasis and erythrodermic psoriasis may be life-threatening." The NHS says to call 999 or go to A&E if "your skin quickly turns red and you develop white, pus-filled bumps that join together – redness may be harder to see on brown or black skin," especially with "other symptoms such as your heart beating fast, or a high temperature, or feeling hot, cold or shivery."

Psoriatic arthritis. "Psoriatic arthritis is a form of chronic inflammatory arthritis which affects 30% of patients with psoriasis." "It leads to sausage-shaped swelling of the fingers and toes known as dactylitis." NIAMS: "If you have symptoms of psoriatic arthritis, it is important to see your doctor soon because untreated psoriatic arthritis can lead to irreversible damage."

Heart and metabolism. NIAMS lists "Cardiovascular events, such heart attacks and strokes." and "People with psoriasis may also be more likely to get certain cancers, Crohn’s disease, diabetes, metabolic syndrome, obesity, osteoporosis, uveitis (inflammation of the middle of the eye), liver disease, and kidney disease." That is why "In the clinic, the patient should be screened for type 2 diabetes, hypertension, and dyslipidemia." Weight, smoking and alcohol all feed it: "Obesity makes the symptoms of psoriasis worse." "Studies have shown that the more a person smokes, the worse the symptoms tend to be." "Some studies suggest that excessive alcohol consumption aggravates symptoms."

Body image and mental health — the plan’s nursing focus. "The scaly patches of skin can make many people feel self-conscious about their appearance. Psoriasis can affect a person’s mental health, increasing the risk of anxiety and depression." Over time, "psoriasis has been associated with depression, suicide, alcoholism, smoking, substance abuse, metabolic syndrome, and a variety of skin cancers." And location matters: "patients with psoriasis involving the palms and soles tend to have a much poorer quality of life than those who have psoriasis on other parts of the body." The nursing action is explicit: "The nurse should monitor the patient for self-harm and refer the patient to a mental health counselor."

Eczema is a barrier disease. "Atopic dermatitis, often referred to as eczema, is a chronic (long-lasting) disease that causes inflammation, redness, and irritation of the skin. It is a common condition that usually begins in childhood; however, anyone can get the disease at any age. Atopic dermatitis is not contagious, so it cannot be spread from person to person." The skin cannot hold water or keep things out: "Dysfunction of the epidermal barrier allows irritants and allergens to penetrate the epidermis and trigger inflammation through an exaggerated T-helper 2 (Th2) immune response." "Filaggrin mutations are present in up to 30% of patients with atopic dermatitis."

Itch drives damage, and damage drives itch. "New research suggests that inflammation directly triggers sensations of itch which in turn cause the patient to scratch. This leads to further damage of the skin as well as increased risk for infection with bacteria." Scratching "further aggravates inflammation by stimulating keratinocytes to release proinflammatory cytokines." The bacteria are already there: skin colonization by Staphylococcus aureus is common, "which occurs in more than 90% of patients," and "Colonization with S aureus can worsen inflammation and lead to secondary infection and impetiginization."

It is part of a family of allergic disease. "It is part of the atopic triad, which also includes allergic rhinitis and asthma. These conditions may develop concurrently or sequentially, in a progression known as the atopic march." It is common in children — "Atopic dermatitis affects approximately 10% to 30% of children and 2% to 10% of adults in developed countries" — and often fades: about 60% of cases start in the first year of life, "and about 60% resolving by age 12." Where it appears changes with age: infants on the face, scalp and around the joints (rarely the diaper area), children in the bends of the elbows and knees, neck and ankles, and "Adults typically present with chronic lichenified lesions with accentuated skin markings, often affecting the hands."

The complication that cannot wait. "A recognized complication of atopic dermatitis is Kaposi varicelliform eruption, which results from a primary herpes simplex virus infection." "Vesicular lesions typically arise within eczematous skin and may rapidly spread to unaffected areas. Prompt treatment with acyclovir can reduce morbidity." This is eczema herpeticum — clustered blisters in eczema that spread — and it is reported promptly.

Two mechanisms, one look. "Irritant contact dermatitis is a nonspecific response of the skin to direct chemical damage that releases mediators of inflammation predominantly from epidermal cells while allergic contact dermatitis is a delayed (type 4) hypersensitivity reaction to exogenous contact antigens." Allergic contact dermatitis needs a prior exposure: "It is T-cell mediated inflammation of the skin caused by repeated skin exposure to haptens in a sensitized individual. Allergic contact dermatitis has two phases." — sensitization, then elicitation.

Timing tells them apart. "The acute irritant reaction usually reaches its peak quickly, within minutes to few hours after exposure." Allergic lesions come later: "Lesions usually appear 24 to 72 hours after the exposure to the causative agent and reach their peak at approximately 72 to 96 hours." The usual culprits: "Poison Ivy (Toxicodendron, formerly known as Rhus), in the United States, is considered to be the most common cause of allergic contact dermatitis." "Nickel is the most common metal present in artificial jewelry which is the cause of allergic contact dermatitis." And topical antibiotics can be the problem: "Neomycin and bacitracin applied to the areas of stasis dermatitis and leg ulcers may be the cause of allergic contact dermatitis on the legs and feet."

This is an occupational disease for nurses. "It is reported that up to 80% of cases of occupational dermatitis are irritant contact dermatitis," and the sourced example is "hand soap causing irritant dermatitis in a hospital employee." "In healthcare, latex allergy is a very common form of contact dermatitis and can have an impact on clinical practice." One variant is dangerous: contact urticaria, a wheal-and-flare reaction after exposure to the offending topical agent — "While most cases are mild, anaphylactic reactions can occur."

How they work. "The mechanism of action of topical corticosteroids is extensive, involving anti-inflammatory, anti-mitotic, and immunosuppressive properties." "The anti-mitotic effect of topical corticosteroids plays a major role in psoriasis" — slowing the cell turnover that builds plaques. Potency runs across seven US classes, "class I superpotent and class VII least potent."

Where you put it changes how much gets in. "Corticosteroids are better absorbed and more permeable in regions of the thin epidermis, such as the eyelid, than thicker regions of the epidermis, such as the sole. The penetration difference between them varies by 300-fold." Inflamed skin absorbs more — "The penetration increases 2- to 10-fold in diseased states, such as inflammation and desquamation." — and "The application of occlusive dressings significantly enhances absorption." So "Low-to-medium strength preparations should be used for large surface areas to decrease the risk of systemic absorption," and "As a general rule, high-potency corticosteroids should not be used on thin skin, e.g. face, genitals, intertriginous areas, to avoid the risk of skin atrophy."

Local harm. "The most common local effects include atrophy, striae, rosacea, perioral dermatitis, acne, and purpura." "Areas most at risk for atrophy are intertriginous due to thinner skin and increased occlusion." Keep both halves of the atrophy fact: "Atrophy is reversible with cessation of steroid use; however, it may take months for the skin to appear normal again." but "Striae appear histologically as scars and are permanent." Steroids also hide infection: "Topical corticosteroids are contraindicated for bacterial infections as their anti-inflammatory and vasoconstrictive effect will mask the infection, ultimately delaying diagnosis and treatment." More is not better — in atopic dermatitis there is "no beneficial evidence for applying topical corticosteroids more than once daily. Applying it more often only increased adverse effects."

Systemic harm — and children absorb the most. "The systemic adverse effects include glaucoma, hypothalamic-pituitary axis suppression, Cushing syndrome, hypertension, and hyperglycemia." The label: "Systemic absorption of topical corticosteroids can produce reversible HPA axis suppression with the potential for glucocorticosteroid insufficiency after withdrawal from treatment." Children are at greater risk "Because of a higher ratio of skin surface area to body mass," and "HPA axis suppression, Cushing's syndrome, linear growth retardation, delayed weight gain and intracranial hypertension have been reported in children receiving topical corticosteroids." In an infant, "Manifestations of intracranial hypertension include bulging fontanelles, headaches, and bilateral papilledema."

The superpotent limits belong to the product label. For a superpotent steroid such as clobetasol propionate (FDA label): "Treatment beyond 2 consecutive weeks is not recommended"; "Use in pediatric patients under 12 years of age is not recommended."; "Clobetasol propionate gel, cream and ointment should not be used with occlusive dressings."; and it "should not be used on the face, groin, or axillae." When the skin clears, "therapy should be discontinued when control has been achieved." These are the clobetasol label’s rules — check the label of whatever product is ordered rather than applying them to every topical steroid.