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Pruritis and Neurocutaneous Dermatoses

Pruritis and Neurocutaneous Dermatoses. KCOM/Texas Dermatology Residency Consortium July 2003. Pruritis. Fine unmyelinated C fibers Also control touch, temperature and pain Subepidermal to lateral spinothalamic tract Spinothalamic tract to thalamus Thalamus to sensory cortex.

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Pruritis and Neurocutaneous Dermatoses

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  1. Pruritis and Neurocutaneous Dermatoses KCOM/Texas Dermatology Residency Consortium July 2003

  2. Pruritis • Fine unmyelinated C fibers • Also control touch, temperature and pain • Subepidermal to lateral spinothalamic tract • Spinothalamic tract to thalamus • Thalamus to sensory cortex

  3. 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.

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

  5. Substance P • 11 amino acid peptide implicated as causing itching in some disorders. • Depletes cutaneous nociceptor nerve endings of Substance P after repeated topical application.

  6. 5-hydroxytryptamine (5-HT) • Regulates 5-HT receptors, may be therapeutic • Ondansetron (Zofran) anti-emetic blocks 5-HT. • Therapeutic in cholestatic pruritis

  7. 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.

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

  9. Treatment • Non sedating antihistamines: • Loratidine (Claritin, Alavert) • Fexofenadine (Allegra) • Acrivastine (Semprex D) • Cetirizine (Zyrtec)

  10. Treatment • Bag of ice • Hot water bottle • “Caine” preparations good for short term relief but often become sensitizers • Doxepin cream or Pramoxine • Sarna (menthol lotion)

  11. 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

  12. Paroxysmal Pruritis • Sudden in onset, irresistably severe, intense pleasure with scratching • LSC, AD, Nummular, DH, Neurodermatitis, Eosinophilic folliculitis, Uremia, Prurigo, Prurigo Nodularis

  13. 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

  14. 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.

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

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

  17. 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 

  18. 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

  19. Renal Failure/Uremic Pruritis • MC internal cause of pruritis • 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

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

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

  22. 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

  23. 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

  24. 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)

  25. Pruritis 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.

  26. 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

  27. 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

  28. 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

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

  30. Prurigo/Prurigo Nodularis • Extremities – Papules/nodules, firm, verrucous in late lesions • Bleeding, scarring, chronic, paroxysmal. • Severe but itch is restricted to lesions themselves • Bx R/O PLEVA, DH, TAD, Scabies, AD, Insect bite, Papular urticaria, Contact. • Treatment and Etiology: Unknown.

  31. Prurigo Nodularis with secondary bacterial infection

  32. 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.

  33. 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

  34. 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

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

  36. 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

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

  38. Neurotic Excoriations • Patient often unaware they are doing it • Compulsion: Tension -> Picking -> Relief • Acne excorie de jeune filles • MC assocs: depression, OCD and anxiety • TOC: Doxepin, Buspar. • Co-manage with a therapist to manage self-aggressive behaviors.

  39. ACNE EXCORIE

  40. Factitious Dermatitis • Self Inflicted for secondary gain  sympathy, escape responsibility, disability. • Distinctive clear cut bizarre appearance. • Usually linear & arranged symmetrically • Chemical burns, injected foreign material, sharp instruments, tight cords  lymphedema, injection of air  crepitus/subutaneous emphysema, non-healing post-op wound.

  41. Factitious Dermatitis • How do you prove the diagnosis ? • Occlusive dressing, ie cast, unna boot. • Biopsy with polarization to r/o FB. • If the patient is hospitalized, a resourceful nurse may be helpful. • Psych consult usually refused. • DOC: Pimozide, Prozac.

  42. Trichotillomania • Varying lengths of broken hairs present and lack of nail pitting helps R/O AA. • MC: frontal scalp, eyebrows, eyelashes. • Onychophagy / nail biting may be present. • Etio: Psychosocial stress in the family • Bx: perifollicular hemorrhage, pigment casts, trichomalacia • Assoc: Depression, OCD, Anxiety • Child Psychiatrist consult, Anafranil, Prozac.

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