Prurigo [L. “the itch”] Papules induced by scratching The term “Besnier's prurigo” is applied to the chronic papular or lichenified form of atopic eczema

Nodular Prurigo (Prurigo Nodularis)

Etiology The cause is unknown Emotional stress seems to be a contributory factor in some cases In 20% the condition starts after an insect bite There is increase in number of neutrophils, mast cells, Merkel cells and IL-31

Clinically Patients are mostly middle-aged to elderly They complain of a long-standing history of severe, unremitting pruritus and they can point out specific sites where they began feeling itchy The patient's medical history may reveal hepatic or renal dysfunction, local trauma to the skin, infection, anxiety or other psychiatric condition

The early lesion is red, and may show a variable urticarial component All lesions are pigmented Crust and scale may cover recently excoriated lesions, and there is an irregular ring of hyperpigmentation immediately around the nodules

The lesions are usually grouped, and numerous, but vary in number They usually develop initially on the distal parts of the limbs & are worse on the extensor surfaces There are crises of pruritus of intense severity New nodules develop from time to time, and existing nodules may remain pruritic indefinitely, although some may regress spontaneously to leave scars. The disease runs a very protracted course

Treatment Local applications are of little value, but direct injection of the nodules with a steroid such as triamcinolone is often helpful Thalidomide is probably the most effective treatment, if it is not contraindicated by the risk of pregnancy Menthol, capsaicin cream, and topical anesthetics are some other topical agents used to reduce pruritus

Cyclosporin, azathioprine and topical capsaicin have been used with success in some cases UV-B or PUVA may be beneficial for severe pruritus A thorough assessment of the patient's emotional state is desirable, and tranquillizers may provide relief in some cases

Surgical Care Cryotherapy with liquid nitrogen helps reduce pruritus and flatten lesions Pulsed dye laser therapy may help reduce the vascularity of individual lesions.

Erythroderma

It is a scaling erythematous dermatitis involving 90% or more of the cutaneous surface

Etiology The most common causes of ED are (ID-SCALP(: Idiopathic(red man syndrome) - 30% Drug allergy(Allopurinol, aspirin, anticonvulsants, barbiturates, captopril, cefoxitin, chloroquine, chlorpromazine, cimetidine, lithium, griseofulvin, nitrofurantoin, omeprazole) - 28% Different types of eczema - 15% Lymphoma and leukemia - 14% Psoriasis - 8%

Less common causes Dermatophytosis Lichen planus Lupus erythematosus Pityriasis rubra pilaris Pemphigus foliaceus and pemphigoid

An increased skin blood perfusion occurs resulting in heat loss and hypothermia and possible high-output cardiac failure Fluid loss by transpiration is increased. The situation is similar to that observed in patients following burns (negative nitrogen balance characterized by edema, hypoalbuminemia, loss of muscle mass)

A marked loss of exfoliated scales occurs that may reach 20-30 g/d A marked loss of exfoliated scales occurs that may reach 20-30 g/d. This contributes to the hypoalbuminemia commonly observed in ED. Hypoalbuminemia results, in part, from decreased synthesis or increased metabolism of albumin Edema is a frequent finding, probably resulting from fluid shift into the extracellular spaces

Clinically Patients may have a history of the primary disease (e.g. psoriasis, atopic dermatitis) or drug use Pruritus is a prominent and frequent symptom and commonly results in excoriations. Malaise, fever, and chills may occur

Patients often present with generalized erythema Scaling appears 2-6 days after the onset of erythema, usually starting from flexures When ED persists for weeks, hair may shed; nails may become ridged and thickened and also may shed Periorbital skin may be inflamed and edematous, resulting in ectropion

Idiopathic ED is characterized by marked palmoplantar keratoderma, dermatopathic lymphadenopathy, and a raised level of serum IgE and is more likely to persist than other types Residual signs of the original disease may be found e.g.: - Islands of sparing in PRP - Few typical psoriatic plaques in psoriasis - Papules or oral lesions of lichen planus - Superficial blisters of pemphigus foliaceus

Investigations If the cause of ED is in doubt, survey patients for occult tumors Primary disease may be evident by skin biopsy

Treatment Discontinue all unnecessary medications. Carefully monitor and control fluid intake, since patients can dehydrate or go into cardiac failure; monitor body temperature, since patients may become hypothermic Apply tap water–wet dressings (made from heavy mesh gauze); change every 2-3 hours. Apply intermediate-strength topical steroids (e.g. betamethasone) beneath wet dressings

Suggest a tepid bath (may be comforting) once or more daily between dressing changes. Reduce frequency of dressings and gradually introduce emollients between dressing applications as ED improves Use systemic antibiotics if signs of secondary infection are observed

Antihistamines help reduce pruritus and provide needed sedation Systemic steroids may be helpful in some cases but should be avoided in suspected cases of psoriasis and staphylococcal scalded skin syndrome Ensure adequate nutrition with emphasis on protein intake