15cases are familial and autosomal dominantly inherited. A subtypecaused by HIV has been reported in recent years.

The follicles are dilated and filled with keratin. The peripheralepidermis is thickened and there is parakeratosis in some parts.Complete keratinization alternates with incomplete keratiniza-tion. Polymorphonuclear cells do not infiltrate into the epidermis,which is useful for differentiation from psoriasis. Vasodilationand lymphocytic infiltrate are observed in the upper dermis.

Pityriasis rubra pilaris should be differentiated from psoriasis,cutaneous T-cell lymphoma, seborrheic dermatitis, drug eruption,ichthyosis and contralateral progressive erythrokeratoderma.

Both types heal spontaneously, within a year in the juveniletype and within 2 to 3 years in the adult type. The symptomatictherapies are application of urea ointments, salicylic acid petrola-tum ointments, and active forms of vitamin D3 ointments. Oralretinoid is also useful.

It is a generic term for diseases that produce multiple psoriasis-like keratotic erythema. The pathogenesis is unknown, but it isthought to be different from that of psoriasis. Some large-plaque

3. Parapsoriasis en plaque

Treatment, Prognosis

Differential diagnosis

Pathology

Clinical images are available in hardcopy only.

Fig. 15.25-2 Guttate psoriasis on the buttocks.

Table 15.7 Classification of pustular psoriasis.

Localizedtype

Generalizedtype

Classification

Localized pustular psoriasis

Pustular psoriasiswith generalizedskin lesion

Generalized pustular psoriasis (GPP)

Impetigo herpetiformis

Clinical findings

Pustules are localizedaround the plaques ofpsoriasis vulgaris.

Pustules are localizedbilaterally on the thenarand arch of the foot.

Often occurs secondarilyafter an external injury.Pustules and nail deformity occur on thetips of fingers or toes onone side of the body.

Psoriasis vulgaris progresses to be accompanied by systemic symptoms.Poor prognosis.

The systemic symptomsare milder than those ofvon Zumbusch psoriasis.

Pustules are generalizedduring the middle and laststages of pregnancy.

Palmoplantarpustulosis (PPP)

Acrodermatitiscontinua of Hallopeau

Acute generalizedpustular psoriasis(von Zumbuschpsoriasis)

Subacute, circularpustular psoriasis

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248 15 Disorders of Abnormal Keratinization

15

parapsoriasis may be prodromes of mycosis fungoides. However,there are many cases in which small-plaque and large-plaqueparapsoriasis occur at the same time.

1) Small-plaque parapsoriasis

Monomorphic round to oval erythematous plaques of 2 to 5cm in diameter appear mainly on the trunk. Lesions are asympto-matic, and histopathologically findings are non-specific. Emol-lients and UVB are helpful.

2) Large-plaque parapsoriasis

Large erythematous or yellowish atrophic plaques occur on thetrunk and extremities. The lesions persist for many years, andgradually increase in number and affected area. They occur mostfrequently in middle-aged and elderly men (Fig. 15.28). Subjec-tive symptoms such as itching are not present. The eruptions are

Clinical images are available in hardcopy only.Clinical images are available in

hardcopy only.Clinical images are available in

hardcopy only.

Fig. 15.27 Pityriasis rubra pilaris.There are follicular papules, diffuse keratinization on the hands and soles, and orange psoriatic plaques.

Clinical images are available in hardcopy only.

Clinical images are available inhardcopy only.

Clinical images are available inhardcopy only.

Fig. 15.26 Pustular psoriasis.The main skin lesions are sterile pustules.

Clinicalimages areavailable inhardcopy

only.

MEMOParapsoriasisThe definition, concept and diagnostic namefor parapsoriasis have not been clarified. Inthe 1970s, it became widely accepted thatlarge-plaque parapsoriasis and small-plaqueparapsoriasis are two distinct disorders. Inrecent years, large-plaque parapsoriasis hascome to be regarded as the early patch stageof mycosis fungoides. Pityriasis lichenoides isknown to be a parapsoriatic disease, and it isclassified into pityriasis lichenoides chronica(PLC; formerly called guttate parapsoriasis)and pityriasis lichenoides et varioliformisacuta (PLEVA; also called Mucha-Haber-mann disease).

B. Acquired keratoses 249

15

usually more than 5 cm in diameter and accompanied by poikilo-derma. Some but not all patients may develop mycosis fungoides(Fig. 22.35). Careful check up of the disease course is necessary.PUVA therapy is effective.

This disorder is difficult to classify. This entity is sometimesregarded as cutaneous vasuculitis, rather than as a keratotic disor-der. Pityriasis lichenoides tends to be limited to the trunk, thighsand upper arms. It rarely occurs on the face, palms or soles. Theeruption progresses slowly over the course of many years. Adultmen are most commonly affected. Erythema or rose pink papulesof several millimeters to 1 cm in diameter, to which white scalesare attached, appear. The eruptions are continuously produced,and a distinguishing characteristic of the disorder is the presenceof new eruptions together with older ones (Figs. 15.29-1 and15.29-2). It is asymptomatic. It heals with pigmentation or depig-mentation. Pityriasis lichenoides is divided into two main forms,Pityriasis lichenoides chronica (PLC) and Pityriasis lichenoideset varioliformis acuta (PLEVA), but intermediate forms orpatients with both forms are often seen.

① Pityriasis lichenoides chronica (PLC)Synonym: guttate parapsoriasis

This is a chronic form. This individual eruption is a rose pinkplaque. Young adults are usually affected.

4. Pityriasis lichenoides

Clinical images are available in hardcopy only.

Fig. 15.28 Large-plaque parapsoriasis.Relatively sharply demarcated slight erythema ispresent.

Clinical images are available in hardcopy only.

Clinical images are available in hardcopy only.

Fig. 15.29-1 Pityriasis lichenoides chronica.Old eruptions are rarely seen simultaneously withnew ones on the lesion. Ulceration does not occur.

Table 15.8 Classification and features of parapsoriasis.

Parapsoriasis en plaque and pityriasis lichenoides

Pityriasis lichenoides (guttate parapsoriasis)

Pityroid scales and erythema appear. Itching is notpresent.

Lymphocytic infiltration in the dermo-dermal junctions

The eruption is 5 cm or more in diameter, accompanied by atrophy, and may be a precursor ofmycosis fungoides in some cases.

The eruption is less than 5 cm in diameter.

Clinical findings

Pathological findingsLarge-plaqueparapsoriasis

Small-plaque parapsoriasis

Clinical findings

Pathological findingsPityriasis lichenoideschronica (PLC)(previous guttateparapsoriasis)

Pityriasis lichenoideset varioliformis acuta(PLEVA)

Fine white scales, erythema of 1 cm or less in diameter, polymorphic skin lesion with old and neweruptions

Lymphocytic infiltration to the epidermis

The main symptom is erythematous plaque.

The main symptoms are severe inflammatory symptoms and ulceration.

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