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
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•
•
•
•
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
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•
•
•
•
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. 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