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Pruritus and Neurocutaneous Dermatoses

Pruritus and Neurocutaneous Dermatoses. Boris Ioffe, D.O. November 2005 . Pruritus. Itch Affects skin, tracheal mucous membrane, and mucocutaneous junctions Often perceived as most unedurable symptom Feature of many systemic diseases Pruritoceptive or neurogenic

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Pruritus and Neurocutaneous Dermatoses

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  1. Pruritus and Neurocutaneous Dermatoses Boris Ioffe, D.O. November 2005

  2. Pruritus • Itch • Affects skin, tracheal mucous membrane, and mucocutaneous junctions • Often perceived as most unedurable symptom • Feature of many systemic diseases • Pruritoceptive or neurogenic • Maybe a sole symptom in the normal skin

  3. Pruritus • Mediated by • Fine unmyelinated C fibers • Also control touch, temperature and pain • Subepidermal to lateral spinothalamic tract • Spinothalamic tract to thalamus • Thalamus to sensory cortex

  4. Central Itch Perception • Sedation effect may decrease “central” itch perception regarding antihistamines like Atarax. • Histamine is a “peripheral” mediator of itch perception • Naloxone is a “central” opiod antagonist for patients with pruritic cholestasis.

  5. Mediators of Pruritus • Histamine, Kinins, Proteases • Prostaglandin E lowers threshold for histamine induced pruritus • Enkephalins, pentapeptides which bind to opiate receptors in the brain modulate pain and itching centrally. • Interleukins implicated in AD.

  6. Histamine • Mediator of signs and symptoms of inflammation including pruritus • Contained in granules of mast cells • Acute and Chronic Urticaria and Mastocytosis • Probably does not have a great role in atopic dermatitis since non-sedating H1 blockers are not effective

  7. Substance P • 11 amino acid peptide implicated as causing itching in some disorders • Causes pruritus, vasodilation and increased vascular permeability • Releases histamine from dermal mast cells • Capsaicin depletes cutaneous nociceptor nerve endings of Substance P after repeated topical application.

  8. 5-hydroxytryptamine (5-HT) • Weak pruritogen, can cause pruritus via central mechanism • Regulates 5-HT receptors • Ondansetron (Zofran) anti-emetic blocks 5-HT. • Therapeutic in cholestatic pruritus

  9. Variations in Intensity of itch… • Psychological trauma • Stress • Absence of distractions • Anxiety, fear • Anatomic regions very susceptible to pruritis: ear canals, eyelids, nostrils, perianal, genital areas.

  10. Treatment • Tricyclics: Doxepin, Amitriptyline • Antihistamines: 1st line: • Promethazine (Phenergan) • Diphenhydramine (Benadryl) • Hydroxyzine (Atarax, Vistaril) • Azatadine (Rynatan)

  11. Treatment • Non sedating antihistamines: • Loratidine (Claritin, Alavert) • Fexofenadine (Allegra) • Desloratidine(Clarinex) • Cetirizine (Zyrtec)

  12. Antihistamine Classification

  13. Treatment • Topical choices • Doxepin 5% cream – percutanoues absorption • Capscaicin 0.025-03% • Menthol 1% lotion • Crotamilton 10%

  14. Treatment • Bag of ice • Hot water bottle • “Caine” preparations good for short term relief but often become sensitizers

  15. TX: Severe Recalcitrant • HIV, CRF, Liver failure • IV Lidocaine – limited by hypotension and short duration of action • Pruritis of cholestasis: • Naloxone • Ondansetron 8mg per day

  16. Paroxysmal Pruritus • Sudden in onset, irresistibly severe, intense pleasure with scratching • LSC, AD, Nummular, DH, Neurodermatitis, Eosinophilic folliculitis, Uremia, Prurigo, Prurigo Nodularis

  17. Labwork/Internal Causes • CMP: Liver disease, Renal Failure, DM II • Hepatits Panel: Hepatitis C • TSH: Thyroid (high or low) • CBC: Anemia, Polycythemia Vera, Leukemia, Myeloma, Hodgkins Lymphoma, Intestinal Parasites • CXR: R/O Cancer

  18. Internal Causes of Pruritis • 10-25% of Hodgkins patients have itch (continuous and at times burning) as a symptom, and for 7% it is the FIRST presenting symptom. • 3% to 47% of patients with generalized pruritis unexplained by skin lesions may have internal cancer.

  19. Polycythemia Vera • 1/3 of these patients report pruritus • Pruritus is induced by temperature changes • Treatment: Low dose ASA, PUVA, Interferon alpha-2b, chemotherapy. • NOTE: Antihistamines ineffective

  20. Biliary Pruritus • Chronic liver disease with obstructive jaundice is the cause • 20-50% of pts with jaundice have pruritus • Central mechanism: elevated CNS opioid peptide levels -> Naloxone treatment • Bile acid levels do not correlate with severity of pruritus

  21. Primary Biliary Cirrhosis • Women > 30 • Starts insidiously, becomes intolerable • Jaundice with striking melanotic hyper-pigmentation of the entire skin - except for a “butterfly area” of normal pigmentation in the upper back 

  22. Primary Biliary Cirrhosis • Xanthomas also seen. • Antimitochondrial antibody test + • Alk. Phos, Ceruloplasmin, Bilirubin, Cholesterol • Tx: Cholestyramine, Rifampin, Naloxone, SAM, Prednisolone, Colchicine, Ursodeoxy-cholic acid, Liver Transplant

  23. Renal Failure/Uremic Pruritus • Uremic pruritus has implication that symptoms are due to raised BUN, not true • 50-90% of dialysis patients within 6 mos. • Dialysis related = episodic • Uremic = generalized, intractable, severe • Causes are multifactorial • TX: Regular dialysis, Epoetin, Emollients, Topical Capsaicin, Antihistamines, Cholestyramine, UVB, Thalidomide

  24. XEROSIS AND PRURITIS IN PATIENT WITH CHRONIC RENAL FAILURE ON HEMODIALYSIS

  25. Winter Itch • AKA Asteatotic Eczema, Eczema Craquele • Cause: frequent harsh bathing in winter • Elderly • TX: Lubrication of skin immediately after bathing • Lac-Hydrin 12%

  26. Pruritis Ani • Neurodermatitis, paroxysmal • Requires ruling out other causes: • Allergic contact from creams applied • Irritation: spicy foods, cathartics, leakage, may need change in diet • Fungal cultures, KOH, DTM, Nickersons, Wood’s lamp exam, Bacterial culture. • Stool for Ova and Parasites, Pinworm. • Anal gonorrhea frequently overlooked

  27. Pruritis Ani • Treatment • Meticulous toilet care using soft cellulose tissue paper and whenever possible washed with mild soap and water. • Wet toilet tissue preferred • Tucks, Balneol, Pramosone • Allow cultures to direct specific therapy

  28. Pruritis Scroti • LSC variant • Infections possible but unlikely • Candida produces burn more than itch • Low potency steroids only as skin here can get steroid addicted • Pramosone (Pramoxine) , Zonalon (Doxepin)

  29. Pruritus Vulvae • MC cause is non-specific dermatitis • Candida infection common during pregnancy/post oral antibiotics • Consider LS&A, Dysesthetic Vulvodynia and Psoriasis. Also Trichomonas Treatment same as Pruritis Scroti • Treatment failure should prompt referral or biopsy.

  30. Puncta Pruritica (Itchy Points) • One or two intensely itching spots in clinically normal skin, sometimes followed by the appearance of SK. • Treatment CRYO, Curettage or Punch biopsy

  31. Aquagenic Pruritis & Aquadynia • AP provoked by water at any temperature usually with family history of the same • Degranulation of mast cells within minutes • Aquadynia is a “burning” variant of AP • Assoc: polycythemia vera, hypereosinophilic synd, JXG, myelodysplastic synd. • TX: OAH, Prednisone, OS, Capsaicin, NTG, Propranolol, Clonidine

  32. Scalp Pruritis • Elderly patients • Non-scaling, non-erythematous, without excoriations (cannot diagnose SD, PV or LSC) • Probably a chronic folliculitis of some sort • Cause unknown in most cases • TX: difficult, tar, SA, TS, IL steroids, OAH

  33. Drug Induced Pruritus • Chloroquine • Amiodarone • Hydroxyethyl Starch or HES (Volume expander, human plasma substitute)

  34. Prurigo Nodularis • Chronic skin condition • Multiple nodules and papules with central-crust • Often but not always due to intense pruritus • Usually affects middle-aged women • Multiple excoriations and postinflammatory changes • Face and soles are rarely effected • Multiple etiologies for pruritis

  35. Prurigo Nodularis with secondary bacterial infection

  36. Prurigo Nodularis • Path: focal hyperkeratosis with non-specific dermal infiltrate • Treatment • Often refractory • Stop itch-sratch cycle • Doxepin • Topical antipruritics(pramoxine,steroids) • IL steroids, cryotherapy, UVB, thalidomide

  37. Prurigo Pigmentosa • Rare, etiology unknown • Japanese women in spring and summer • Sudden onset of erythematous papules that leave reticulated hyperpigmentation when they heal, often recurrent. • upper back, nape, clavicular & chest • H&E lichenoid infiltrate w/ psoriasiform hyperplasia • Minocycline 100mg BID, Dapsone.

  38. Papuloerythroderma of Ofuji • Rare, Japan • Widespread flat topped papules that strikingly spare the skin folds, producing bands of uninvolved cutis, known as the DECK CHAIR SIGN • PATH: dense lymphohist. infilt. w/ eosinophils in papillary dermis • Assoc: HIV, lymphoma • TX: Oral steroids

  39. Lichen Simplex Chronicus • AKA Neurodermatitis Circumscipta • Result of long term rubbing/scratching • Striae form a criss-cross pattern, and between them is a mosaic of flat topped, shiny smooth quadrilateral facets • Paroxysmal, neck, wrists, ankles • TX: TS, IL, Occlusion, Zonalon, Capsaicin

  40. PSYCHODERMATOLOGY • Onychophagia – nail biting • Dermatophagia – biting one’s own skin • Lip licking “clown mouth make-up” • OCD – compulsive hand washing • Bulimia – crusted papules on dorsum of hands from cuts by teeth • Fist clenching – fingertip swelling and ecchymosis, subungual hemorrhage

  41. Irritant Hand Dermatitis Pearl • OCD is often the cause, repetitive hand- washing • Growing body of evidence supporting a neurobiological cause of disease • Treatment with Clomipramine, Fluoxetine, Fluvoxamine, Sertraline, Paroxetine, Venlafaxine • Behavioral therapy

  42. Delusions of Parasitosis • “Matchbox sign” • Belief is “fixed” in patient’s mind • Monosymptomatic Hypochandrial Psychosis • Middle aged or elderly women MC. • Work-up: Bx, CBC, UA, LFTs, TSH, Iron, B-12, Folate, Electrolytes. • Psych consult usually refused. • Pimozide 1 to 12mg plus Cogentin or Benadryl to allay Extrapyramidal SE • Newer antipsychotics

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