Prurigo

Dr Yugandar

• 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.

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

• 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.

Pruriginous dermatoses

• Nodular prurigo

• chronic prurigo

• prurigo pigmentosa

• prurigo of pregnancy

• actinic prurigo.

• 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

• 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.

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

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.

• history of atopic dermatitis

• Aetiology : unknown, Hyde is

credited with being the first describe

• Hyde’s prurigo, prurigo simplex

chronica,

and lichen obtusus corneus

• Woman > man• No genetic factos• Some authors suggested with atopic

eczemaearly-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

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.

• 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

• Keratinocyte and fibroblast

activation: acanthosis,

parakeratosis,and hyperkeratosis of

the epidermis

• Thes changes are due to the chronic

stimulation of keratinocytes by

scratching

• 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

• 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

• 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.

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

• 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

• 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

• 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

• 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

• 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.

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

• 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,

• 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

• 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

Differential Diagnosis

• 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.

• 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

• Calcineurin inhibitors :• topical tacrolimus• antipruritic effect of calcineurin

inhibitors can possibly be explained by their anti-inflammatory effect and direct effect on nerve fibers

• Vitamin D3 analogues : topical therapy

calcipotriol, tacalcitol

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

• 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

• Cannabinoid agonists: • Topical use of the cannabinoid

agonists N-palmitoylethanolamine (PEA)

• 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

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

• 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

• 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

Parthenium dermatitis manifesting clinicallyas polymorphic light eruption and prurigo

nodularis-

LATE ONSET NODULARPRURIGO – THE SOLE AND INITIAL

MANIFESTATION OF OCCULTHODGKIN’S DISEASE