Pruritus , Prurigo
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Pruritus and prurigo Professor Danka Švecová MD, PhD. Dept.of Dermatovenerology Faculty of Medicine Comenius University Pruritus • Pruritus or itch – unpleasent sensation→provokes a desire to scratch • Underlying systemic disease – 10-50% Pathogenesis – sensation of pruritus is transmitted through slow-conducting unmyelinated C-polymodal and A-d nociceptive neurons with free nerve endings – in dermal-epidermal junction or within epidermis – are more sensitive to pruritogenic substances than to pain receptors →histamine, neuropeptide substance P, serotonin, bradykinin, protease, endothelin →impulses are transmitted from the dorsal-root ganglia to the spinothalamic tract Pruritus secondary to skin diseases (Pruritus cum materia) • Atopic dermatitis • Lichen planus • Insect bites • Drug eruption • Psoriasis→may cause itching • Urticaria → no scratching but rubbing, no excoriations • Dermatitis herpetiformis→ excoriations often the only findings before the lesions appear • Impetigo→localised pruritus • Folliculitis → sometimes is pruritic in HIV/AIDS Pruritus secondary to skin diseases (Pruritus cum materia) • Infestation is common cause of pruritus; Scabies→ severe itching at night, family members; Pediculosis capitis →excoriation on the nape; Pediculosis pubis→ pubic area Pediculosis corporis→ trunk Atopic dermatitis Atopic dermatitis Lichen planus Lichen planus Insect bite Insect bite Drug eruption Urticaria Dermatitis herpetiformis Dermatitis herpetiformis Cutaneous infestations Scabies Scabies Cutaneous infestations Pediculosis capitis Pediculosis capitis Pediculosis pubis Pruritus secondary to systemic disease (Pruritus sine materia) • Renal pruritus (chronic renal failure, haemodialysis) cause→ histamine, opioids, neural proliferations, some unknown pruritogenic substance, xerosis, elevated levels of bile acids, vitamin A, serotonin • Cholestatic pruritus cholestasis; cause→ bile salts, histamine, opioids, unknown pruritogen from damaged hepatocytes; 60% of patients with primary biliary cirrhosis suffer from pruritus • Haematologic pruritus→ iron deficiency, polycythemia vera – increased number of circulating basophils, skin mast cells- itch during cooling after a hot shower →45-70% have aquagenic pruritus; release of serotonin and prostaglandins – contributing factors Pruritus secondary to systemic disease (Pruritus sine materia) • Endocrine pruritus hyperthyroidism → increased tissue metabolism – active kinins, or reduced itch threshold (warmth and vasodilatation; hypothyreodism → xerosis; diabetes mellitus→cause and effect remain unproven (metabolic abnormalities, autonomic dysfunction, anhidrosis, diabetic neuropathy • Pruritus in malignancy → release of toxins, immune system; lymphoma – pruritus precede Dg by five years (intolerable, continuous, severe, burning) Hodgkin disease→ leukoptidase, bradykinin –pruritogenic mediators; patients with severe, generalised pruritus have shorter survival than those with mild or no pruritus. Carcinoid syndrome → pruritus is triggered by serotonin Pruritus secondary to systemic disease (Pruritus sine materia) • Pruritus of various origins→ mastocytosis, HIV/AIDS, sarcoidosis, dermatomyositis, Sjögren syndrome, brain abscess, drug-induced pruritus without rash; parasitic infections→ hookworms, pinworms, trichinosis (Trichinella spiralis), gnathostomiasis (Gnathostoma spinigerum), gardiasis (Gardia species), ascariasis (Ascaris species), onchocerciasis (Onchocerca species); parvoviral infection, leptospirosis; chronic fatigue syndrome; chemical intoxication with mercury or diaminodiphenylmethane Pruritus: Diagnostic criteria • Primary dermatologic disoredrs mast be excluded before a systemic cause is considered • History: onset, duration, severity, location, provoking factors, time relation, relation to activities such as bathing, drug history, alcohol abuse history (liver disease), history of potential emotional stress, menthal health history Pruritus: Therapy • First goal → to treat the underlying disease • Antihistamines → H1 and H2 blockers • Emollients • Systemic corticosteroids → occasionally in inflammatory disorders • Physical therapy → UVB irradiation, narrow-band UVB (uremic pruritus); UVA and UVA1; PUVA and bath PUVA Localized pruritus • Dry skin→ first step – lubrication (bland ointments, bath oil), topical anaesthetics; topical capsaicin; tacrolimus ointment; tar or tar baths, topical antihistamines helpful in short time Prurigo • Condition with intense itching; acute, subacute of various origin; chronic form appears to be idiopathic • Sometimes associated with atopy, pregnancy, internal diseases, malabsorption, malignancy; • Emotional factors can influnce the perceptation of itch and induce prurigo by provoking scratching Prurigo simplex acuta (Strophulus infantum) Reccurent allergic reaction to arthropod bites or stings affecting mostly children aged 2-8 years, especially in summer and early autumn Aethiology and pathogenesis - result of an arthropod bite or sting; probably a combination of types I and IV of reactions; more common in rural areas in summer months; resolves when the patient is hospitalized; other suspected causes→dietary intolerance or eating of unripe fruit Prurigo simplex acuta (Strophulus infantum) Clinical findings→ Primary lesion →intensely pruritic seropapules with a pale red, elevated border, disseminated or grouped; trunk and extremities; sometimes sparely visible vesicles or larger bullae (strophulus bullosus); seropapule evolves rapidly into a firm hard papule, losing its erythematous border; Prurigo simplex acuta (Strophulus infantum) Lesions are itchy; when scratched, become denuded producing crusts; Secondary impetiginisation is common, Lesions in various degree of evolution; Healing with hyper- or hypopigmentation, without scars; Dif.Dg→ multiple insect bites, varicella (scalp, mouth, fever), scabies (night itch, genitalia, groin, axillae) Therapy→ systemic antihistamines, topical antipruritic agents Prurigo simplex subacuta (Strophulus adultorum) Subacute or chronic inflammatory cutaneous disorder, women aged 20 or after menopause, most patients have neurotic behaviour patterns and may overreact to the pruritus, underlying atopic diathesis Aetiology and pathogenesis –cause is unknown; initial type I reaction coupled with the later type IV reaction; variety of pruritic backgroud → Actinic prurigo→ a type of photosensitivity Prurigo aestivalis→a variant of polymorphic light eruption Prurigo Besnier → in atopic patients Prurigo dysmenorrheica→ prior to menses – autoimmune progesterone dermatitis Prurigo hepatica→ in hepatic diseases Prurigo lymphatica→ malignant lymphoma or leukaemia Prurigo paraneoplastica→ underlying malignancy Prurigo uremica→in renal disease Prurigo simplex subacuta (Strophulus adultorum) Clinical findings intense pruritus; pruritus is relieved when scratched until the lesion bleeds; Primary lesion → a palpable papule as a tiny grain; rapidly scratched until bleeds; shoulder girdle, lateral sites of the thighs; Secondary lesion → crusted excoriation, atrophic scars, hypopigmented, hyperpigmented periphery Prurigo simplex subacuta (Strophulus adultorum) DifDg neurotic excoriation, the history of primary lesion is decisive to distinguish both dg; atopic patiens show other signs of underlying disease Therapy mainstay th → systemic antihistamines, tranquilisers; underlying disease should be treated; systemic corticosteroids → little efficacy, reccurence is frequent topical capsaicin, tacrolimus, high-potency corticosteroids physical th → UVB, UVA, PUVA, bath PUVA Prurigo simplex chronica Closely related to prurigo nodularis; Causes → the same as in prurigo simplex subacuta; Lesions persist for long time, they are hyperpigmented dome-shaped nodules with hyperkeratotic surface, 0.4 –1 cm Therapy → high potency corticosteroids ointments under occlusion; intralesional corticosteroids; destruction of nodules using cryotherapy and laser th Prurigo nodularis Disorders with multiple itching nodules on extremities, especially on the anterior surfaces of the thigs and legs; middle –aged elderly Aetiology and pathogenesis - cause is unknown; chronic mechanical traumatizing causes thickening of the skin, pruriginous nodule is considered the result of repetitive rubbing, scratching and touching; possibly at the site of a former bite, folliculitis or prurigo lesion; type I reaction to pollen, dust, house dust mites support the role of underlying atopy; association with internal malignancy, severely decreased renal function, HIC infection Prurigo nodularis Clinical findings – distal aspects of the extensor surfaces of arms and legs, while the trunk is spared, nodules range 0.5 – 3 cm, discrete, firm, symmetric; early lesions → erythematous tone, later lesions→ red-grey or dirty grey; dull, not shiny, hyperkeratotic; excoriation → lesions are flat, umbilicated, crusted top, normal color or hyperpigmented; Pruritus → paroxysmal, intermittent, severe, relieved only by scratching to the point of damaging the skin, bleeding and often scaring; chronic course, patient is miserable Prurigo nodularis DifDg verrucous lichen planus (other signs of lichen planus, mucosal surfaces), prurigo simplex chronica (seropurulent papules) Prurigo nodularis Therapy difficult and challenging; → Combination of several medication or physical modalities; systemic antihistamines, tranquilisers, opiate receptor antagonists → Intralesional or topical corticosteroids with occlusion; menthol, phenol, capsaicin cream, vitamin D analogues (calcipotriol, tacalcitol), topical anaesthetics ; → UV irradiation therapy → UVB, UVA, UVA1, PUVA; topical immunomodulators tacrolimus, pimecrolimus; cryotherapy with liquid nitrogen; → Pulsed dye laser therapy (reduces the vascularity of individual lesions).