Pruritus and Atopic Dermatitis Overview

Pruritus Overview

• Is a sensation that provokes a desire to scratch
• The first cause to consider for pruritus is dry skin
• Can be caused by skin disorders like scabies and atopic or contact dermatitis
• Other skin disorders which may generate this sensation are drug reactions, urticaria, psoriasis, lichen planus, and bullous pemphigoid
• Systemic disorders such as thyroid and parathyroid issues, lymphoma or leukemia can cause it
• Other systemic disorders include iron deficiency anemia, HIV, hypercalcemia, low vitamin D, cholestasis, and neurologic disorders
• Psychological factors and habits can cause pruritus
• Treatment for pruritus is determined by the cause

Atopic Dermatitis

• It is a chronic and recurring inflammatory skin disease characterized by pruritus
• Commonly affects the face, neck, upper trunk, wrists, hands, and flexural surfaces, like antecubital and popliteal folds
• Presents as dry, scaly plaques and lichenified areas, with the possibility of erythematous papules, vesicles, exudation, crusting, and fissures
• Patients often have a personal or family history of allergic disease or atopy
• Commonly occurs in the first year of life and typically diagnosed by age 5
• Is associated with the "Allergic Triad" of asthma, allergic rhinitis, and atopic dermatitis

Atopic Dermatitis Treatments

• Treatment options for atopic dermatitis include oral antihistamines and topical moisturizers, which should be used frequently
• Other topical treatments include anti-itch creams and steroids (based on severity) applied once or twice daily
• Systemic corticosteroids can be considered for severe acute exacerbations
• Topical immunosuppressant medications may be indicated too
• It's important to avoid triggers like low humidity, sweating, and heat
• Patient education should include gentle skin care, emollient use within minutes after bathing, and limiting bathing to once daily without washcloths/brushes
• Patients should pat their skin dry, wear cotton fabric, and monitor for secondary infections

Contact Dermatitis

• Is a cutaneous reaction to an external substance that can be acute or chronic
• There are two types: irritant and allergic
• Irritant contact dermatitis is caused by substances like soaps, detergents, and saliva
• Allergic contact dermatitis is caused by allergens like poison ivy, poison oak, neomycin, nickel, adhesives, rubber, and essential oils

Appearance of Contact Dermatitis

• Irritant contact dermatitis presents as pruritic, erythematous, and scaly skin, with possible vesicles at the site of direct contact
• In chronic cases, it can lead to scaling, erythema, and thickened skin
• Allergic contact dermatitis presents as pruritic vesicles and weeping, crusting lesions that extend beyond the area of contact
• These lesions can be edematous and warm, with erythematous macules and papules in a typically linear arrangement

Poisonous Plants: Oak and Ivy

• Poison oak leaves are usually 3-7 cm in length, have lobulated notched edges, and grow in groups of 3, 5, or 7 on bush-like plants, turning colors in autumn
• Poison ivy leaves are usually 3-15 cm in length, have notched edges, and grow in groups of 3 on hairy-stemmed vines or low shrubs, also turning colors in autumn

Contact Dermatitis - Causative Agent Avoidance

• Identifying and avoiding possible allergens is important
• Protecting the skin with clothing and gloves can help
• Some allergens can pass through latex gloves
• Prompt removal with liquid soap within 30 minutes of exposure is important
• OTC barrier creams can be effective if applied prior to exposure

Contact Dermatitis - Treatment

• Topical treatments include moisturizing lotions with zinc oxide, talc, or menthol
• Corticosteroid creams (OTC, low/medium/high potency if needed) and emollient creams/ointments (petrolatum) are options
• Antibiotic ointments or oral antibiotics may also be used
• Systemic corticosteroids can also be used

Urticaria

• Itchy red rash that erupts with "wheals/welts" ranging from a few millimeters to several centimeters, and lesions can vary over time
• Usually has an allergic component, often caused by foods, soaps, lotions, medications, or infections
• Angioedema is a serious accompaniment, that can indicate the start of anaphylaxis
• Angioedema involves deeper subcutaneous or submucosal tissue with swelling of the lips, eyelids, palms, soles, and genitalia
• In cases of Angioedema, epinephrine is required
• Can be chronic, lasting more than 6 weeks, and can be spontaneous or chronic inducible
• Autoimmune components are common

Physical or Inducible Urticaria

• Can be induced by heat, like showers and baths
• Cold weather exposure
• Sun exposure stimulates via solar urticaria

Urticaria Treatments

• Identifying the trigger is key, but it can be frustrating and not always found
• First-line treatments include second-generation antihistamines like loratadine and cetirizine, sometimes increased to >40 mg
• First-generation antihistamines like diphenhydramine or hydroxyzine can work well, but can cause sedation
• Second-line treatment is doxepin, a tricyclic antidepressant with antihistamine properties, for chronic urticaria
• Corticosteroids, tapered or in a burst, may also be used

Xerosis

• Commonly occurs on the extremities
• Skin surface becomes rough, flaking, or scaly and hyperpigmentation can be present
• Skin may become erythematous and fissured, turning into xerotic eczema
• Significant pruritus results in excoriation and secondary infections of scarring
• Can be caused by disease states such as postmenopause, hypothyroidism, and chronic renal disease
• It is the most common cause of generalized itching, especially in the elderly
• More common in cold, dry weather and exacerbated by strong alkaline bath soaps
• Patients often mistreat with lotions, soaks, and even alcohol rubdowns

Xerosis Management

• Responds to simple hydration with emollients and the avoidance of contributing factors such as frequent bathing, drying soaps, and lotions with water content
• Mild, pH-balanced soaps like Dove or Cetaphil should be used sparingly
• Avoid hot water and prolonged or frequent bathing or showers
• Avoid excessive towel drying by patting the skin dry
• Apply emollients after bathing and moisturize the air in the house or office
• Use antihistamines as needed

Pediculosis

• Consists of 3 species of lice, wingless insects 2-4 mm in length that cannot fly or jump
• Head lice (Pediculosis capitis) are the most common form
• Pubic lice (Pediculosis pubis) and body lice (Pediculosis corporis) are less common
• Is transmitted through direct contact, with indirect contact via brushes or clothes being less common
• The bites cause urticarial papules and intense itching, lice feed on blood

Lice

• Most frequently seen in school-age children, but head lice is unrelated to hygiene or length of hair
• Clinical manifestations: itching, primary symptom, scratching with secondary excoriation, crawling sensation on the scalp, and eyelash involvement may cause crusting or blepharitis
• Can cause secondary bacterial infection of skin
• Diagnosed through visualization of a live nymph or louse

Lice Facts

• Female lice survive for 30 days on a host
• They lay eggs "nits" on the base of hair, which hatch in 8 days
• Nymphs released take another 8 days to mature
• Can survive for 1-2 days off host

Lice Treatment

• Permethrin 1% cream applied and left on for 8 hours before rinsing off, is more effective if nits removed, resistance can occur
• Malathion lotion 1% is used for resistant cases (Highly volatile and flammable)
• Repeat treatments after 7-9 days to catch any eggs that survived the first treatment
• Manual removal of nits isn't necessary, but can be done using a fine-toothed metal comb
• All infested persons should be treated at the same time
• Wet combing can be used if too young for treatment or want to avoid the chemical treatment
• Oral ivermectin is available if topical treatments fail
• Household treatments: wash bedding, towels, and clothes with hot water and dry with high heat
• Anything that can't be washed should be put in a plastic trash bag and sealed for 2 weeks
• Vacuum rugs, furniture, mattresses, and car seats thoroughly
• Return to school is permitted after the first effective treatment, it does not have to be nit-free

Scabies

• Most common human infestation caused by the mite Sarcoptes scabiei
• The mite burrows into the epidermis and deposits her eggs
• The eggs mature in 10-14 days
• Highly contagious and transmission occurs with close physical contact for 15-20 minutes or bedding
• Clinical Manifestations of scabies include severe itching, red, excoriated papules, vesicles, pustules and burrows in the axillae, umbilicus, elbow, groin, penis, instep of the foot, web spaces/interdigital of hands/feet
• Classically has a linear papule or burrow - but can be difficult to find because it is only 2-3mm long
• Usually spares head and neck, but not always

Scabies Treatment

• Treatment is an 8-12 hour application of permethrin 5% cream applied to the entire body from the neck down then washed off
• This is repeated in 1 week
• All household contacts and caregivers should also be treated
• Itching can persist for up to several weeks after treatment
• Household treatment includes washing bedding, towels, and clothes in hot water then drying in high heat
• Items that cannot be washed should be sealed in a plastic bag for 14 days