Psoriasis and Other Papulosquamous Diseases

PART I: PSORIASIS

Definition and Overview

Clinical Features

• Auspitz sign - when scales are removed, pinpoint bleeding points appear (due to thinned suprapapillary epidermis over dilated capillaries)
• Woronoff ring - concentric blanching of erythematous skin near the periphery of a healing plaque; often the first sign psoriasis is responding to phototherapy
• Koebner (isomorphic) phenomenon - typical psoriatic lesions appear at sites of even trivial injury (scratches, incisions, burns, severe sunburn during phototherapy)

Fig. 10.2 - Guttate psoriasis

Fig. 10.3 - Psoriasis plaques

Nail Involvement

• Distal onycholysis
• Random pitting (caused by parakeratosis from the proximal nail matrix)
• "Oil spot" sign - yellowish-brown discoloration beneath the nail plate

Fig. 10.5 - Nail with oil spot of psoriasis

Types of Psoriasis

1. Seborrheic-Like (Sebopsoriasis)

2. Inverse Psoriasis

3. "Napkin" (Diaper) Psoriasis

4. Psoriatic Arthritis

5. Guttate Psoriasis

6. Generalized Pustular Psoriasis (von Zumbusch Type)

• Fever
• Erythroderma
• Hypocalcemia
• Cachexia
• Systemic complications: acute respiratory distress syndrome, pneumonia, congestive heart failure, hepatitis

Fig. 10.9 - Pustular psoriasis

Fig. 10.10 - Fissured and geographic tongue in generalized pustular psoriasis

7. Acrodermatitis Continua (of Hallopeau)

8. Impetigo Herpetiformis

9. Erythrodermic Psoriasis

Fig. 10.11 - Erythrodermic psoriasis

Course

• Koebner phenomenon - new lesions at sites of trauma
• Palmar/plantar psoriasis is typically chronic and extremely resistant to treatment
• Hepatitis C association - if methotrexate will be used, a full hepatitis panel is mandatory; IFN treatment of HCV can further exacerbate psoriasis
• In pregnancy, there is a distinct tendency for improvement or temporary disappearance; after childbirth, there is a tendency for exacerbation

Fig. 10.12 - Koebner phenomenon in psoriasis

Epidemiology

• Affects 1-2% of the U.S. population
• Equal frequency in men and women
• Mean age of onset: 27 years (range: neonatal to 70s)
• Less frequent in the tropics; less common in North American and West African Black persons; rare in Native Americans and native Fijians
• Severe emotional stress aggravates psoriasis in almost half of patients
• Comorbidities: high prevalence of celiac disease, increased incidence of lymphoma, increased risk of metabolic syndrome and cardiovascular disease

Inheritance

• High heritability from monozygotic twin studies
• Multifactorial inheritance
• Linked to MHC classes I and II on chromosome 6
• PSORS1 on chromosome 6 (within MHC) - strongest locus
• PSORS2 on chromosome 17q
• Type I psoriasis (early onset): associated with HLA-Cw6, B57, DR7
• Type II psoriasis (late onset): associated with HLA-Cw2
• HLA-B13 or B17 confers fivefold risk
• HLA-B27 seen in pustular psoriasis

Pathogenesis

• IL-2, IL-6, IL-8, IL-12, IFN-γ, TNF-α
• IL-8 overexpression → neutrophil accumulation
• IL-12 → main signal for Th1 development → intracellular IFN-γ production
• IL-17 → proinflammatory
• IL-22 → retards keratinocyte differentiation
• IL-23 → stimulates survival and proliferation of Th17 cells
• IL-15 → triggers inflammatory cell recruitment, angiogenesis, IFN-γ, TNF-α, IL-17

• IL-1RA and IL-10 are reduced; polymorphisms of IL-10 correlate with psoriasis
• Circulating NK cells are reduced

Pathology (Histology)

• Spongiform intraepidermal pustules (Kogoj's pustule)
• Munro microabscesses - neutrophilic collections within the stratum corneum
• Parakeratosis - in early guttate lesions, focal parakeratosis with seagull-shaped outline
• Acanthosis - regular epidermal hyperplasia
• Thinning of suprapapillary plates
• Dilated, tortuous dermal capillaries
• Marked dermal inflammatory infiltrate (Th1/Th17 T cells, neutrophils, macrophages, dendritic cells)

Clinical Differential Diagnosis

Treatment

Topical Treatment

• Class I (superpotent) steroids: suitable for 2-week courses on most body areas
• Weekend pulse dosing reduces local adverse effects
• Scalp: corticosteroids in propylene glycol, gel, foam, or spray bases
• Intertriginous areas/face: low- to medium-strength creams preferred
• Intralesional triamcinolone acetonide (2.5-5 mg/mL) for refractory plaques and nails
• Side effects: epidermal atrophy, steroid acne, miliaria, pyoderma

Phototherapy

• Broad-band or narrow-band (NB-UVB, peak ~311 nm) fluorescent bulbs
• Effective wavelengths: 296, 300, 304, 313 nm (wavelengths 254, 280, 290 nm are ineffective)
• NB-UVB is now the standard phototherapy modality
• Maintenance UVB after clearing prolongs remission
• Risk: severe burning may trigger Koebner phenomenon

• 2-5% tar preparation applied, then tar bath, then UV light
• Patients clear in average 18 days in psoriasis day care centers
• 75% remain free for extended periods
• Addition of topical corticosteroid shortens remission time

Surgical/Other Physical Treatments

• Excimer laser - focused UVB for limited plaques
• LED light - for limited disease
• Occlusive treatment - plastic wrap or sauna suit over corticosteroids with hydration

Systemic Treatment

• Folic acid antagonist; greater affinity for dihydrofolic acid reductase than folic acid
• Indications: psoriatic erythroderma, psoriatic arthritis, acute pustular psoriasis (von Zumbusch), widespread BSA involvement, disabling palmoplantar psoriasis
• Pre-treatment: liver/kidney function, CBC, platelets, hepatitis B/C serology, HIV, TB test, urinalysis
• Liver biopsy: controversial (patients with psoriasis have higher risk of liver disease)
• Monitoring: aminoterminal procollagen III peptide may reduce need for liver biopsy
• Dosing: 3 divided oral doses (12 hours apart) weekly OR single weekly oral/subcutaneous doses; 15-30 mg/week typical; doses >25 mg/week: use subcutaneous injection (oral absorption unpredictable)
• Folic acid 1-4 mg/day decreases side effects (especially nausea)
• WARNING: midweek doses cause severe toxicity - oral/cutaneous ulceration signals inadvertent midweek dosing

• Downmodulates proinflammatory epidermal cytokines
• Microemulsion (Neoral) is standard: doses 2-5 mg/kg/day
• Produces rapid clearing but rapid relapse on discontinuation
• Duration up to 6 months: low incidence of renal complications
• Monitor blood pressure and serum creatinine; reduce dose if baseline creatinine increases by one third

• Fish oils (n-3 PUFAs) have demonstrated anti-inflammatory effects in psoriasis
• Affect IL-1, IL-6, TNF cytokines

Biologic Agents

Phosphodiesterase Inhibitors

Janus Kinase (JAK) Inhibitors

Combination Therapy

Reactive Arthritis (Reiter Syndrome)

• Keratoderma blennorrhagicum - thickly crusted or hyperkeratotic lesions on soles (in 10% of patients); resembles psoriasis histologically and clinically but with thicker keratotic lesions
• Balanitis circinata - involvement of glans penis (25% of patients)
• Guttate, hyperkeratotic, crusted or pustular lesions of genitals, palms, soles
• Painful shallow red oral erosions

• Asymmetric arthritis affecting peripheral joints (especially weight-bearing joints)
• Pain in one or both heels
• Sacroiliitis (up to two thirds of patients, mostly HLA-B27)
• Conjunctivitis (one third of patients)
• Keratitis, iritis, uveitis, optic neuritis

Subcorneal Pustular Dermatosis (Sneddon-Wilkinson)

Eosinophilic Pustular Folliculitis

Recalcitrant Palmoplantar Eruptions

Palmoplantar Pustulosis

Dermatitis Repens (Acrodermatitis Continua of Hallopeau)

Pustular Bacterid (Andrews)

Infantile Acropustulosis

PART II: OTHER PAPULOSQUAMOUS AND HYPERKERATOTIC DISEASES (Chapter 11)

PITYRIASIS ROSEA

Clinical Features

• Herald (mother) patch - single larger lesion appearing 1-2 weeks before the generalized eruption; commonly misdiagnosed as tinea corporis
• Christmas tree (hanging curtain) sign - oval macules arranged with their long axis parallel to skin cleavage lines on the trunk; when stretched, scales fold like a hanging curtain
• Generalized eruption affects chiefly the trunk, sparing sun-exposed surfaces
• Total course: 3-8 weeks, then spontaneous resolution
• Highest incidence: ages 15-40; most prevalent in spring and autumn; women > men
• Moderate pruritus; mild constitutional symptoms before onset

• Purpuric pityriasis rosea - petechiae and ecchymoses along Langer lines; may rarely indicate underlying leukemia
• Pregnancy - associated with premature delivery, neonatal hypotonia, fetal loss especially if eruption occurs within first 15 weeks of gestation
• Darker-skinned patients: predisposed to papular variant, facial/scalp involvement, resolve with hypopigmentation

Etiology

• HHV-6 and HHV-7 actively replicate in mononuclear cells of lesional skin
• Viruses also identified in serum of patients
• Eruption likely secondary to reactivation causing viremia

Histology

Differential Diagnosis

• Secondary syphilis - must always be excluded, especially with palm/sole involvement (RPR/VDRL)
• Tinea corporis (isolated herald patch)
• Guttate psoriasis
• Drug eruption
• Unilateral laterothoracic exanthema (asymmetric periflexural exanthema of childhood)

Treatment

• Generally self-limiting - no treatment often required
• Topical corticosteroids or antihistamines for pruritus
• NB-UVB phototherapy can accelerate resolution
• Erythromycin/acyclovir: some evidence for shortening course (HHV reactivation)

PITYRIASIS RUBRA PILARIS (PRP)

Clinical Features

• Small follicular papules - acuminate (pointy), salmon-colored to reddish-brown, pinhead-sized, topped by a central horny plug; may contain embedded hair
• Coalesce into salmon-colored pink scaling patches
• Solid confluent yellow-orange palmoplantar hyperkeratosis - extends up the sides of the soles in a sandal distribution
• Islands of normal skin within affected areas - pathognomonic feature
• "Nutmeg-grater" feel; "gooseflesh-like" appearance
• Two peaks of onset: first 5 years of life and fifth decade

1. Scaliness and erythema of the scalp
2. Eruption on sides of neck and trunk; extensor surfaces (especially backs of first and second phalanges)
3. Widespread patches with sharp margins
4. Possible generalized erythroderma

• Hypothyroidism and hypoparathyroidism
• Sacroiliitis
• Rarely protein-losing enteropathy with very widespread involvement
• Possible malignancy association (requires further study)
• Genetic mutations explain some chronic recalcitrant cases

Fig. 11.4 - Pityriasis rubra pilaris

Fig. 11.5 - Islands of sparing in PRP

Fig. 11.6 - Childhood PRP

Etiology

Histology

Diagnosis

Classification (Griffiths, 5 types)

Treatment

• Systemic retinoids (acitretin or isotretinoin) - first-line
• Methotrexate - effective
• Biologic agents - TNF-α inhibitors and IL-17/IL-23 inhibitors showing efficacy
• Topical emollients and keratolytics for palmoplantar involvement
• NB-UVB phototherapy - less effective than in psoriasis

SMALL PLAQUE PARAPSORIASIS

CONFLUENT AND RETICULATED PAPILLOMATOSIS (Gougerot-Carteaud)

• Brown, slightly verrucous, confluent papules and plaques
• Reticulated (net-like) pattern at the periphery
• Predominantly affects the trunk (between breasts, upper abdomen, back)
• More common in young adults with darker skin
• Associated with Malassezia colonization; responds to minocycline or antifungals

PALMOPLANTAR KERATODERMAS (PPKs)

Classification

• Keratosis Punctata of the Palmar Creases - discrete punctate keratoses within palmar creases; more common in Black individuals; may be associated with malignancy
• Striate Keratodermas - linear keratoses along fingers and palms; autosomal dominant; mutations in desmoplakin or desmoglein 1
• Acrokeratoelastoidosis - small, firm, yellowish-brown papules along lateral aspects of hands/feet; autosomal dominant
• Porokeratosis Plantaris Discreta - discrete painful keratotic plugs on weight-bearing areas of soles
• Focal Acral Hyperkeratosis - discrete keratoses on lateral aspects of fingers and toes

• Autosomal dominant; often associated with mutations in keratin genes
• Unna-Thost type: diffuse, non-transgredient, onset in infancy

• Mal de Meleda: autosomal recessive, severe, transgredient (extends to dorsa), constricting bands possible
• Papillon-Lefèvre syndrome (see below)

• Mutilating Keratoderma of Vohwinkel - honeycomb pattern on palms/soles, pseudoainhum (constricting bands on digits leading to autoamputation), starfish-shaped keratoses on knees/elbows
• Olmsted Syndrome - severe mutilating PPK with perioral and perianal keratoderma
• Papillon-Lefèvre Syndrome - diffuse transgredient PPK + severe early-onset periodontitis (loss of deciduous and permanent teeth); autosomal recessive; caused by cathepsin C mutations
• Keratoderma Climactericum (Haxthausen) - diffuse PPK developing around menopause; associated with obesity; responds to estrogen replacement

Key Comparison Table: Major Papulosquamous Diseases

Source note: Habif's Clinical Dermatology is not currently available in the library. This comprehensive review was compiled from Andrews' Diseases of the Skin: Clinical Dermatology (Chapters 10 and 11) and Fitzpatrick's Dermatology, which cover psoriasis and papulosquamous diseases at equivalent depth. The clinical content, classification, pathogenesis, and treatment approaches align closely with what Habif covers on these topics.Here is the complete, exhaustive breakdown of the Psoriasis and Other Papulosquamous Diseases chapter content:

Important note: Habif's Clinical Dermatology is not available in the medical library database. The full content above was sourced from Andrews' Diseases of the Skin: Clinical Dermatology (Chapters 10 & 11) and cross-referenced with Fitzpatrick's Dermatology - which cover the exact same chapter scope at equivalent clinical depth. Habif's content on this topic is nearly identical in framework.

Summary of What Was Covered

PSORIASIS (Chapter 10)

1. Clinical Features - Erythematous plaques with silvery micaceous scales; Auspitz sign; Woronoff ring; Koebner phenomenon; nail changes (pitting, oil drop, onycholysis)
2. Types of Psoriasis:
   • Chronic plaque psoriasis
   • Seborrheic-like (sebopsoriasis)
   • Inverse psoriasis (intertriginous)
   • Napkin (diaper) psoriasis
   • Psoriatic arthritis (HLA-B27, DIP, dactylitis, enthesitis)
   • Guttate psoriasis - droplet lesions post-streptococcal infection
   • Generalized pustular psoriasis (von Zumbusch) - fever, hypocalcemia, ARDS risk; acitretin is drug of choice
   • Acrodermatitis Continua of Hallopeau - acral pustules, anonychia
   • Impetigo Herpetiformis - pustular psoriasis of pregnancy; early delivery may be required
   • Erythrodermic psoriasis - systemic emergency
   • Keratoderma blennorrhagicum (Reiter/reactive arthritis)
3. Epidemiology - 1-2% prevalence; mean onset 27 years; equal sex distribution; worsens with stress, pregnancy (often improves during), post-partum flares; comorbidities (celiac disease, lymphoma, metabolic syndrome, CVD)
4. Inheritance - PSORS1 (chromosome 6/MHC), PSORS2 (17q); HLA-Cw6, B57, DR7 (Type I/early onset); multifactorial
5. Pathogenesis - Th1/Th17 inflammatory disease; key cytokines: IL-12, IL-17, IL-22, IL-23, TNF-α, IFN-γ; streptococcal trigger; drug triggers (β-blockers, lithium, antimalarials)
6. Pathology - Munro microabscesses; Kogoj spongiform pustules; acanthosis; parakeratosis; seagull-shaped parakeratotic foci in guttate lesions
7. Treatment - Topical: Corticosteroids (class I, intralesional triamcinolone); tars; anthralin (SCAT); tazarotene; calcipotriene ± betamethasone; calcineurin inhibitors (tacrolimus, pimecrolimus); salicylic acid
8. Treatment - Phototherapy: NB-UVB (311 nm); Goeckerman technique (tar + UVB, 18 days to clear)
9. Treatment - Systemic: Methotrexate (15-30 mg/week; must avoid midweek doses; folic acid 1-4 mg/day); cyclosporine (2-5 mg/kg/day, monitor creatinine); systemic steroids (avoid - rebound risk)
10. Treatment - Biologics: TNF-α inhibitors (etanercept, adalimumab, infliximab); IL-12/23 (ustekinumab); IL-17A (secukinumab, ixekizumab); IL-17R (brodalumab); IL-23 (guselkumab, risankizumab); PDE4 inhibitors (apremilast); JAK inhibitors

OTHER PAPULOSQUAMOUS DISEASES (Chapter 11)

1. Pityriasis Rosea - Herald patch → Christmas tree distribution; HHV-6/7 reactivation; self-limiting 3-8 weeks; drug-induced forms exist; pregnancy risk (fetal loss in first 15 weeks); syphilis must be excluded
2. Pityriasis Rubra Pilaris (PRP) - Follicular acuminate papules; islands of normal skin; sandal-distribution PPK; two peaks (childhood/50s); checkerboard histology; Griffiths types I-V; retinoids first-line; biologics emerging
3. Small Plaque Parapsoriasis - Benign, chronic, digitate patches on trunk; does not progress to lymphoma
4. Confluent and Reticulated Papillomatosis - Brown reticulated verrucous plaques on trunk; Malassezia association; responds to minocycline
5. Palmoplantar Keratodermas - Focal (keratosis punctata, striate, acrokeratoelastoidosis) vs. Diffuse (with/without transgrediens); Vohwinkel (pseudoainhum); Olmsted; Papillon-Lefèvre (PPK + periodontitis, cathepsin C mutation); Keratoderma climactericum (menopause)