Pruritus and dysesthesia Flashcards
What three classifications should be made for pruritus?
- Affecting diseased (inflamed) skin? -Affecting non-diseased (non-inflamed) skin
- Presenting with chronic secondary scratch-induced lesions
What are some red flags which may suggest underlying disease as cause of pruritus?
Chronic or generalized pruritus, age older than 65, abnormal physican exam findings such as organomegaly, LAD, etc.
What are some components of a history that suggest a benign course?
Younger age, localized sx’s, acute onset, involvement limited to exposed areas, clear association with sick contact or recent travel.
What 6 categories of dermatologic disease should be thought of in pruritus?
Inflammatory, infestation/bits/stings, infections, neoplastic, genetic/nevoid, other
What is prurigo nodularis?
Chronic repetitive scratching/picking 2/2 pruritus or dermatologic disease or psych condition that causes reactive papules/nodules
Clinical of prurigo nodularis?
Multiple pruritic, dome-shaped, firm hyperpigmented papulonodules that may have a central scale/crust/erosion. The ulcerations are distributed symmetrically on extensor extremities with sparing of hte mid-back (butterfly-sign)
Where is prurigo nodularis most commonly seen?
Middle-aged adults with underlying dermatologic/psychiatric disorder and occasionally in children with atopy
Treatment of prurigo nodularis?
SSRIs/TCAs for underlying psychologic condition, doxepin, MTX, thalidomide/lenalidomide, topical capsaicin, calcipotriene, liquid nitrogen, and cyclosporine
What is lichen simplex chronicus?
Hypertrophy of the epidermis as a result of chronic, habitual rubbing or scratching of the skin.
Clinical of lichen simplex chronicus?
Clinically appears as well-defined plaques with lichenification, hyperpigmentation and varying erythema Favors posterior neck, occipital scalp, anogenital region, shins, ankles, and dorsal hands, feet, forearms. Predisposing factors include xerosis, atopy, stasis dermatitis, anxiety, obsessive–compulsive disorder, and pruritus related to systemic disease. Broader, thinner lesions than prurigo nodularis but w/ same itch-scratch cycle perpetuating the condition
Treatment of lichen simplex chronicus?
treat underlying systemic or psychiatric illness if present; avoidance of scratching/rubbing; topical/ intralesional agents (corticosteroids and calcineurin inhibitors); topical antipruritics (menthol and pramoxine), antihistamines, and behavioral therapy
What is scalp pruritus?
May be primary: lacks skin lesions; a/w anxiety and dpression Or, secondary to dermatoses: psoriasis, seb derm, and folliculitis
Treatment for scalp pruritus?
emollients and topical steroids; tar or salicylic acid shampoos, and low dose doxepin
Epidemiology of pruritus ani?
Pruritus of anus and perianal skin (1%–5% population); male ≫ female
Clinical of pruritus ani?
Skin appearance: normal to severely irritated (erythema/crusting/lichenification, erosions/ulcerations)
Cause of pruritus ani?
Primary pruritus ani: pruritus in absence of cutaneous, anorectal, or colonic disorder; may be due to dietary factors, poor personal hygiene, or psychologic disorders Secondary pruritus ani: due to irritation from stool or hemorrhoids or fissures, primary cutaneous disorders, infectious or infestations, previous XRT, neoplasms, or contact allergy
Tx for pruritus ani?
reduce irritation w/ sitz baths, cool compresses, meticulous hygiene, mild topical steroids (class 6 or 7) or topical calcineurin inhibitors, and treatment of underlying disorder
What is pruritus scroti/vulvae?
Acute or chronic pruritus of scrotum or vulva; worse at night; lichenification secondary to repeated rubbing/scratching
Pathogenesis of pruritus scroti/vulvae/
acute: infections, allergic or irritant contact dermatitis; chronic: secondary to dermatoses, malignancy, atrophic vulvovaginitis, lumbosacral radiculopathy, irritation, or psychogenic (1%–7% patients)
What is aquagenic pruritus?
Severe pruritus or burning pain after water contact, irrespective of water temperature; within 30 min of contact with no visible skin changes; lasts up to 2 hrs; spares head, palms/soles, and mucosae
Pathogenesis of aquagenic pruritus?
usually secondary to systemic disease (e.g., polycythemia vera) or other skin disorder
Treatment fo aquagenic pruritus?
alkalization of bath water to pH 8 with baking soda, oral antihistamines, phototherapy, and capsaicin; clonidine and propranolol for aquadynia
How common is post-burn pruritus?
85% of burn patients experience pruritus
What is the pathogenesis of pruritus in scars/
Sequence of physical and chemical stimuli as well as nerve regeneration A disproportionate number of thinly myelinated and unmyelinated C-fibers in immature or abnormal scars may contribute to increased itch perception. Physical stimuli include direct mechanical stimulation of nerve endings during scar remodeling Histamine, vasoactive peptides such as kinins, and prostaglandins E1/E2 act as chemical mediators and may account for a “chemogenic” pruritus.
Tx for pruritus a/w scar?
Treat with ILK and/or silicone gel sheets, oral pentoxifylline (400 mg 2–3 times daily)
Tx for fiberglass pruritus?
talcum powder, or tape
What percentage of pt’s w/ no primary dermatologic cause but have pruritus have an underlying systemic condition (presenting to a derm office)
14-24%
What percentage of patients with kidney disease have pruritus?
>50% of patients with CKD have pruritus and 80% of those on dialysis
When is the pruritus 2/2 CKD worse?
Pruritus peaks @ night after 2 days w/o dialysis, is relatively high during tx and is lowest during the day following dialysis
Is pruritus in those with CKD a prognostic indicator?
Renal pruritus is an independent marker of mortality for pt’s on hemodialysis
What is the mechanism of pruritus in CKD?
Mechanism unclear. No relationship between the plasma histamine level and severity of pruritus -Peripheral neuropathy affects up to 65% of patients who receive dialysis -Pruritus may be a manifestation of a neuropathy? -Caused by loss of itch-inhibiting CGRP-expressing neurons in the papillary dermis potentially
Do antihistamines work in pruritus of CKD?
No
Treatment options for those with pruritus of CKD?
Topical capsaicin, topical y-linolenic acid, topical pramoxine, activated charcoal, gabapentin, pregabalin, UVB phototherapy, cholestyramine, naltrexone, ondansetron, nalfurafine, ondansetron, nalfurafine, ketotifen, cromolyn sodium, montelukast, thalidomide, lidocaine, erythropoietin
What are the most common entities which cause biliary pruritus?
primary biliary cirrhosis, primary sclerosing cholangitis, obstructive choledocholithiasis, carcinoma of the bile duct, chronic hepatitis C/ viral hepatitis