Prurigo

Prurigo: Types & management

1. Prurigo Dr Yugandar

2. Group of skin diseases characterized by intensely pruritic papules or nodules . Some authors have stressed the intense pruritus visible excoriations No identifiable local cause for the scratched lesions.

3. chronic inflammatory skin disorder characterized by severe pruritus and papules and nodules with excoriations and ulcerations due to scratching.

4. Prurigo is derived from the Latin and means “itch”, which simply refers to the common feature shared by all pruriginous diseases , a sometimes intractable pruritus . The term was originally introduced by Hebra He denote papules induced by scratching.

5. Pruriginous dermatoses Nodular prurigo chronic prurigo prurigo pigmentosa prurigo of pregnancy actinic prurigo .

6. Acute Prurigo : Urticarial erythema or wheals appear and become exudative papules , usually in small children k/a Strophulus infantum Subacute prurigo : urticarial papule accompanied by intense itching occurs on extensor surface of the extremities or the trunk.when it is rubbed and scratched, erosion or crust forms

7. Chronic prurigo : prurigo chronica multiformis,with aggregated individual papules that tend to form a lichenoid lesion; prurigo nodularis , with large nodular papules that form sparsely and individually.

8. Prurigo chronica multiformis : trunk and legs of the elderly Exudative or solid papules aggregate to form invasive plaques. The lesions are rubbed as a result of intense itching, and exudate and crusts form to present intermingled pruritic papules and lichenoid lesions. often chronic, with recurrences and remissions

9. Nodular prurigo Nodular prurigo is characterized clinically by chronic, intensely itchy nodules and histologically by marked hyperkeratosis and acanthosis, with downward projections of the epidermis.

10. history of atopic dermatitis Aetiology : unknown, Hyde is credited with being the first describe Hyde’s prurigo , prurigo simplex chronica, and lichen obtusus corneus

11. Woman > man No genetic factos Some authors suggested with atopic eczema early-onset atopic Late-onset atopic Close a/w atopic D Initial manifeatation at 19 a/w environmental allergens Initial manifestation at 48 years No h/o atopic D No a/w allergens

12. Etiopathogenesis severe chronic pruritus leads to repetitive mechanical trauma as a result of scratching, and chronic skin irritation then leads to a characteristic tissue reaction marked by recruitment of a lymphocyte-rich inflammatory infiltrate, activation of epidermal keratinocytes , a circumscribed increase in collagen tissue, and activation & proliferation of peripheral sensory nerves.

13. Leukocyte recruitment and activation : after mechanical trauma primary pro-inflammatory cytokines such as interleukin(IL)-1 and tumor necrosis factor alpha (TNF- α) induce chemokine cascades in keratinocytes Recruitment of Lymphocytes, eosinophils , and mast cells

14. Keratinocyte and fibroblast activation: acanthosis, parakeratosis,and hyperkeratosis of the epidermis Thes changes are due to the chronic stimulation of keratinocytes by scratching

15. Activation of sensory neurons: marked hyperplasia of peripheral cutaneous nerves peripheral nerves in prurigo nodularis lesions have increased amounts of nerve growth factor (NGF)- receptor p75. produce high levels of NGF, calcitonin gene related peptide and substance P

16. A further study has shown that the vanilloid receptor, subtype 1 (VR1/TRPV1), an ion channel, binds to capsaicin, found in much higher levels on cutaneous nerves in lesional skin in prurigo nodularis patients

17. These results show that activation and proliferation of cutaneous nerves in patients with prurigo nodularis are associated with increased production of the neuropeptides CGRP and substance P possibly intensifying the pruritus via neurogenic inflammatory pathways.

18. CLINICAL FEATURES massive, and sometimes excruciating pruritus extensor aspects of the extremities, the shoulders,and the chest and sacral regions The face, palms of the hands, and plantar surfaces of the feet are usually not affected No involvement of the mucous membranes

19. sharply demarcated,tough , mildly erythematous nodule patients often scratch intensely leading to gray or purple and sometimes verruciform keratotic areas, excoriations, crater-like ulcerations, and hemorrhagic crusts

20. After the lesions heal, residual lesions are left behind with post-inflammation hyperpigmentation or areas of hypopigmentation or Scarring The skin between individual lesions is generally normal,but there is sometimes xerosis cutis

21. The development of nodules first occurs as a result of intense scratching . Typically there is an area of skin that is unaffected which the patient cannot reach, such as the middle of the back . This characteristic feature of prurigo nodularis is referred to as the “butterfly sign” significance of the mechanical trauma for the development of lesions

22. The development of areas of keratosis , excoriation,and ulceration on primary lesions is attributed to the constant irritation caused by scratching “scratching” of a lesion produces only temporary relief from pruritus , which quickly starts again, leading to an “itch-scratch- cycle”which causes the nodules to persist and leads to secondary lesions

23. Due to the simultaneous appearance of recent and older lesions,patients usually present with a Polymorphous appearance consisting of recent nodules , excoriations crater-like ulcerations residual lesions such as hypopigmentation or hyperpigmentation as well as scarring .

24. Histopathology Marked hyperkeratosis focal parakeratosis irregular acanthosis appearance of pseudocarcinomatous or pseudoepitheliomatous hyperplasia arises from papillomatosis and an irregular, downward proliferation of epidermis and epithelia of adnexal structures

25. In the papillary dermis increased amounts of multinucleated fibroblasts as well as thick collagen fiber bundles arranged perpendicularly to the surface. Proliferation of nerve fibers and Schwann cells may be observed. dilated, vertically-oriented capillaries. At the surface, around vessels and in interstitial spaces dense infiltrate of lymphocytes, isolated eosinophilic granulocytes,mast cells, macrophages,

26. More no of Eosinophilic granulocytes with degranulation in atopic diathesis. If there are erosions or excoriations, crusting around the margin with exudation It shows parakeratosis , plasma cells and neutrophils

27. gross accentuation of the changes of lichenifi cation . The epidermal downgrowth is pseudoepitheliomatous in extent. mixed inflammatory cell infi ltrate in the dermis sclerosis of the dermal collagen

28. Differential Diagnosis

29. antipruritic measures should be undertaken to eliminate pruritus cutting the fingernails and wearing cotton gloves instruments such as brushes are used to combat the itching.

30. Topical corticosteroids mometasone furoate or methylprednisolone aceponate application of topical corticosteroids should be under occlusion Intralesional application of corticosteroids : triamcinolone acetonide suspension 10-40 mg/ml

31. Calcineurin inhibitors : topical tacrolimus antipruritic effect of calcineurin inhibitors can possibly be explained by their anti-inflammatory effect and direct effect on nerve fibers

32. Vitamin D3 analogues : topical therapy calcipotriol , tacalcitol

33. Menthol and polidocanol : menthol (0.5-2 %) urea (2-10 %) polidocanol (3-5 %)

34. Capsaicin : Topical capsaicin acts by desensitizing sensory nerve fibers and interrupting transmission of cutaneous pruritus gradually increasing doses (0.025% -0.05 % - 0.075% - 0.1 %). In prurigo nodularis , concentrations of up to 0.3% may be necessary

35. Cannabinoid agonists: Topical use of the cannabinoid agonists N- palmitoylethanolamine (PEA )

36. Phototherapy : broadband UVB, narrow band UVB, narrow band UVB in combination with thalidomide,UVA-1 phototherapy,bath PUVA induction of anti-inflammatory and immunosuppressive factors as well as antiproliferative effects UVB-induced apoptosis of mast cells

37. Systemic antipruritic therapies Antihistamines Cyclosporine : inhibits the function of lymphocytes as well as mast cells Anticonvulsant agents : gabapentin also has an antipruritic effect Antidepressants : mirtazapine , paroxetine , ondansetron , Opioid receptor antagonist: Naltrexone

38. Thalidomide: dosage between 100 mg/day and a maximum of 400 mg/day Roxithromycin with tranilast : roxithromycin at a dosage of 300 mg/day with tranilast (N-(3,4-dimethoxycinnamoyl)) in a dosage of 200 mg/day in patients with prurigo nodularis

39. Cryosurgery: use of liquid nitrogen, depending on their size, vary from 10-30 seconds with two to four “freeze-thaw cycles.” It can take up to four weeks until the treated nodules heal. Residual scarring can occur . After cryosurgery, patients can be pruritus -free for up to three months, Combination therapy with cryosurgery, intralesional triamcinolone acetonide 40 mg/ml

40. Parthenium dermatitis manifesting clinically as polymorphic light eruption and prurigo nodularis -

41. LATE ONSET NODULAR PRURIGO – THE SOLE AND INITIAL MANIFESTATION OF OCCULT HODGKIN’S DISEASE