to a primary disease such as SLE, rheumatic arthritis or hepatitisB. Unlike in ordinary urticaria, type I allergy is not involved inurticarial vasculitis. However, the immune complex that indicatesthe involvement of a type III allergy is present.

Physical stress – from exercise, for example – 1 to 4 hoursafter ingestion of certain foods may cause anaphylaxis andurticaria simultaneously. In Japan, food-dependent exercise-induced anaphylaxis (FDEIA) is most often caused by wheat, fol-lowed in frequency by shrimp, oysters and celery. Since exerciseor ingestion of specific foods alone does not cause FDEIA, aninduction test is necessary to confirm and diagnose FDEIA.

Prurigo is a condition in which there are independentitchy papules or small nodular eruptions.It is induced by insect bite, allergy, or atopic condition. It may be aggravated by rubbing, whereby smallintractable nodules form.

In prurigo, papules or small urticarial nodules are accompaniedby intense itching that becomes chronic. These nodules are calledpruritic papules (Fig. 8.6). There are various etiologies and clini-cal features; however, the condition is thought to be a specificinflammatory reaction. Prurigo is characterized by exudativeinflammatory lesions (Fig. 8.7) and by its failure to develop intothe other types of eruptions that are seen with eczematous anddermatitis lesions. Prurigo remains as chronic papules and nod-ules. It is often categorized as acute or chronic.

Prurigo is exudative inflammation that occurs in the dermalupper layer. It is accompanied by lymphocytic or neutrophilicinfiltration. It is thought to be induced by specific inflammatoryreaction (pruritic reaction); however, the causative agent isunknown in many cases. Insect bites, mechanical or electricalstimulation, certain kinds of foods, and chemical stimulationsuch as by histamines are thought to be causative factors. Prurigomay also accompany malignant tumor, leukemia or Hodgkin’sdisease. Atopic dermatitis can also cause prurigo.

Pathogenesis

Clinical features, Classification

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Outline

4. Food-dependent exercise-induced anaphylaxis (FDEIA)

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Prurigo

Clinical images are available in hardcopy only.

Fig. 8.6 Prurigo nodularis. Small, severely itchy nodules of 5 mm to 20 mmin diameter are noted. Excoriation is also seen.

Clinical images are available in hardcopy only.

Clinical images are available in hardcopy only.

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Synonym: Strophulus infantum

Urticarial erythema or wheals appear and become exudativepapules, usually in small children. Secondary infection may becaused by rubbing and scratching brought on by intense itching.Although acute prurigo tends to last only several weeks, it tendsto recur. Symptoms do not appear after the patient reaches a cer-tain age.

Atopic condition and hypersensitive reaction to insect bite orcertain foods (e.g., eggs, soybeans, pork) are known to be associ-ated with the occurrence of prurigo. Children under age 5 aremostly affected in the summer, when insect stings are common.

Topical steroids and oral antihistamines are the first-line treat-ment. Insect bites and intake of causative foods should be avoid-ed.

Synonym: Prurigo simplex subacuta

An urticarial papule accompanied by intense itching occurs onthe extensor surface of the extremities or the trunk. When it isrubbed and scratched, erosion or crust forms. Subacute prurigo isintractable and may become chronic.

The etiology is unknown. A primary disease such as atopicdermatitis, diabetes, liver dysfunction, lymphoma, leukemia,Hodgkin’s disease, internal malignancy, polycythemia, gout, ure-mia or pregnancy is often involved. Mental stress has also beenpointed out as associated with onset. The clinical features areintermediate between those of acute and chronic urticarias. How-ever, acute and chronic urticarias may be found simultaneouslyin the same patient.

In addition to treatments for the primary disease, topicalsteroids and antihistamines are administered as needed.

Chronic prurigo is subdivided into prurigo chronica multi-formis, with aggregated individual papules that tend to form alichenoid lesion; and prurigo nodularis, with large nodularpapules that form sparsely and individually.

Classification

3. Chronic prurigo

2. Subacute prurigo

Treatment

Pathogenesis

Clinical features

1. Acute prurigo

112 8 Urticaria, Prurigo and Pruritus

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Clinical images are available in hardcopy only.

Fig. 8.8 Prurigo chronica multiformis.

Fig. 8.7 Histopathological findings of pruri-go nodularis. Acanthosis and inflammatory cell infiltration inthe upper dermis are noted. Excoriation induceseven more severe acanthosis.

Clinical images are available in hardcopy only.

Fig. 8.9-1 Prurigo pigmentosa. a: Chest lesion in a young male patient.

aa b c d e f ha g i j k l m n o p q r

Prurigo chronica multiformis occurs most frequently in thetrunk and legs of the elderly (Fig. 8.8). Exudative or solidpapules aggregate to form invasive plaques. The lesions arerubbed as a result of intense itching, and exudate and crusts formto present intermingled pruritic papules and lichenoid lesions.The condition is often chronic, with recurrences and remissions.

Prurigo nodularis most commonly affects adolescents andolder women (Fig. 8.6). Papules and nodules occur in the extrem-ities, accompanied by intense itching. When rubbed they developerosion and bloody crusts, resulting in dark brown solid papulesor nodules. These are isolated and do not coalesce to formplaques. They persist for several years.

Topical steroids or ODT is applied as a local therapy. Applica-tion of a zinc ointment sheet over topical steroids is effective.Oral antihistamines are helpful in relieving itching. Oral steroidsand cyclosporines may be applied for a short period of time insevere cases. Local injection of steroids and phototherapy arealso conducted.

Prurigo gestationis appears on the extremities or trunk ofwomen in their 3rd or 4th month of pregnancy and subsides afterdelivery. It is increasingly likely to occur with each successivepregnancy. Differentiation between prurigo gestationis andPUPPP (pruritic urticarial papules and plaques of pregnancy) iscontroversial; however, the former occurs in the early stages ofpregnancy, whereas the latter occurs in the later stages of preg-nancy.

Prurigo pigmentosa (Nagashima) is urticarial erythema accom-panied by intense itching. Pruritic erythematous papules recurand heal with reticular pigmentation (Figs. 8.9-1 and 8.9-2). Itmost frequently occurs on the back, neck and upper chest of ado-lescent women. The pathogenesis is unknown. Minocycline andDDS (dapsone) are extremely effective treatments.

In pruritus cutaneous there is no obvious eruption; onlyitching is present. It is often accompanied by dry skin (xerosis).Eruptions, lichenification and pigmentation may be ●

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Outline

5. Prurigo pigmentosa (Nagashima)

4. Prurigo gestationis

Treatment

Clinical features

Pruritus cutaneus 113

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Clinical images are available in hardcopy only.

Clinical images are available in hardcopy only.

Fig. 8.9-2 Prurigo pigmentosa. b: Prurigo pigmentosa in a female patient in her20s. Fresh-red erythema are mixed with oldlesions, which are seen as reticular hyperpig-mented macules. c: Erythematous macules(arrows) are seen at the center of reticular hyper-pigmentation. It is a recurrence of prurigo pig-mentosa.

a bb c d e f hb g i j k l m n o p q r

a b cc d e f hc g i j k l m n o p q r

Pruritus cutaneous

produced secondarily by rubbing and scratching.Oral antihistamines and psychological counseling arehelpful.

The disease is classified by distribution into pruritus univer-salis and pruritus localis.

Pruritus cutaneous occurs secondarily to various underlyingdiseases, including liver dysfunction and renal failure (Table8.1). Scarring, thickening of the skin, lichenification and pigmen-tation often develop secondarily by rubbing and scratching. Thedisease is accompanied by dry skin (xerosis). It tends to occurwhen the skin is sensitive to external stimulation, especially inwinter and at bedtime.

Systemic examinations such as blood test and renal functiontest are necessary for diagnosis. When the genitalia are affected,pruritus cutaneous should be differentiated from scabies and can-didiasis.

Treatment focuses on the underlying disease, if detected.Application of antihistamines and moisturizer, and UV irradia-tion are conducted as symptomatic therapies. It is also importantto eliminate pruritus-inducing factors such as alcohol, coffee andspices. Bathing to keep the body clean, wearing cotton clothes,avoiding dryness, and eliminating emotional stress are also help-ful. Topical steroid application is effective against secondaryeruptions; however, it is ineffective against pruritus itself.

Itching is present on the whole body surface. As shown inTable 8.1, it usually accompanies other diseases. In the elderly,pruritus may be present without a disease because of dry skin andage-related processes; this is called senile pruritus.

Itching appears locally in the anal region or genitalia. Prurituslocaris in the anal region, which accounts for most cases of pruri-tus, frequently affects young and middle-aged men. It may becaused by constipation, diarrhea, hemorrhoids and anal prolapse.Pruritus localis of the genitalia is commonly found in middle-aged women. The labia majora and minora are most commonlyaffected. Pruritus localis needs to be differentiated from parasiticinfection.

2. Pruritus locaris

1. Pruritus universalis

Treatment

Differential diagnosis

Pathogenesis

Clinical features, Classification

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114 8 Urticaria, Prurigo and Pruritus

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Table 8.1 Causes of pruritus cutaneous.

Diabetes mellitus, diabetesinsipidus, thyroid disorder,parathyroid disorder

Hepatitis, cirrhosis, carcinoid syndrome, biliaryatresia, gout, etc.

Chronic renal failure, uremia

Erythrocythemia, iron deficiency anemia

Various carcinomas, multi-ple myelomas, malignant lymphoma (in particular,Hodgkin’s disease andmycosis fungoides), chron-ic leukemia

Ascariasis, ancylostomiasis

Myelophthisis, thalamictumor

Mechanical stimuli, dryconditions, spicy foods

Cocaine, morphine,bleomycin, and drugs towhich the patient hashypersensitivity

Seafood (mackerel, tuna,squid, shrimp, clams, etc.),vegetables (aroids, bambooshoots, eggplant, etc.),pork, wine, beer, chocolate

In the third trimester

Excessive stress, compul-sive neurosis and otherpsychogenic disease

senile xerosis

Visceral disorder

Endocrinologi-cal dysfunction

Metabolic dysfunction

Renal disorder

Hematologicaldisorder

Malignancy

Parasitosis

Neurological disorder

Environmental factor

Drug

Food

pregnancy

psychogenic factor

skin dryness

Diffuse pruritus cutaneous

Localized pruritus cutaneous

Pruritus on the Genital region

Pruritus on the perianal region

(Adapted from; Miyachi Y. Minimum dermatology.Bunkodo; 2000).

Prostatic hypertrophy, urethral stricture, vaginaltrichomoniasis, etc.

Constipation, diarrhea, analprolapse, hemorrhoid, etc.

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