Psoriasis affects 1.5-2% of the population in Western countries. Worldwide occurrence.
A chronic disorder with polygenic predisposition and triggering environmental factors such as bacterial infection, trauma, or drugs.
Several clinical expressions. Typical lesions are chronic, recurring, scaly papules, and plaques. Pustular eruptions and erythroderma occur.
Clinical presentation varies among individuals, from those with only a few localized plaques to those with generalized skin involvement.
Psoriatic erythroderma in psoriasis involving the entire skin.
Psoriatic arthritis occurs in 10—25% of the patients.
Chronic stable plaque
Pustular psoriasis of von Zumbusch
Psoriasis Vulgaris ICD-9: 696.1 ICD-10: L40.0
Age of Onset. All ages. Early: Peak incidence occurs at 22.5 years of age (in children, the mean age of onset is 8 years). Late: Presents about age 55. Early onset predicts a more severe and long-lasting disease, and there is usually a positive family history of psoriasis.
Incidence. About 1.5-2% of the population in Western countries. In the United States, there are 3-5 million persons with psoriasis. Most have localized psoriasis, but in approximately 300,000 persons psoriasis is generalized.
Sex. Equal incidence in males and females.
Race. Low incidence in West Africans, Japanese, and Inuits; very low incidence or absence in North and South American Indians.
Heredity. Polygenic trait. When one parent has psoriasis, 8% of offspring develop psoriasis; when both parents have psoriasis, 41% of children develop psoriasis. HLA types most frequently associated with psoriasis are HLA- B13, -B37, -B57, and, most importantly, HLA-Cw6, which is a candidate for functional involvement. PSORS 1 is the only consistently confirmed susceptibility locus.
Trigger Factors. Physical trauma (rubbing and scratching) is a major factor in eliciting lesions. Acute streptococcal infection precipitates guttate psoriasis. Stress is a factor in flares of psoriasis and is said to be as high as 40% in adults and higher in children. Drugs: Systemic glucocorticoids, oral lithium, antimalarial drugs, interferon, and ß-adrenergic blockers can cause flares and cause a psoriasiform drug eruption. Alcohol ingestion is a putative trigger factor.
The most obvious abnormalities in psoriasis are (1) an alteration of the cell kinetics of keratinocytes with a shortening of the cell cycle resulting in 28 times the normal production of epidermal cells and (2) CD8+ T cells, which are the overwhelming T cell population in lesions. The epidermis and dermis react as an integrated system: the described changes in the germinative layer of the epidermis and inflammatory changes in the dermis, which trigger the epidermal changes. Psoriasis is a T cell-driven disease and the cytokine spectrum is that of a TH1 response. Maintenance of psoriatic lesions is considered an ongoing autoreactive immune response.
There are two major types:
1. Eruptive, inflammatory type with multiple small lesions and a greater tendency toward spontaneous resolution (Figs. 3-1 and 3-2); relatively rare (<2.0% of all psoriasis.
Figure 3-1. Psoriasis vulgaris Primary lesions are well-defined, reddish or salmon-pink papules, droplike, with a loosely adherent silvery-white lamellar scale.
Figure 3-2. Psoriasis vulgaris: buttocks (guttate type) Small, discrete, erythematous, scaling, papules that tend to coalesce, appearing after a group A streptococcal pharyngitis. There was a family history of psoriasis.
2. Chronic stable (plaque) psoriasis (Figs. 3-3 and 3-4): Majority of patients, with chronic indolent lesions present for months and years, changing only slowly.
Figure 3-3. Psoriasis vulgaris: elbow Chronic stable plaque psoriasis on the elbow. In this location, scales can either accumulate to oyster shell-like hyperkeratosis, or are shed in large sheets revealing a beefy-red base. This plaque has arisen from the coalescence of smaller, papular lesions that can still be seen on lower arm.
Figure 3-4. Psoriasis vulgaris: chronic stable type Multiple large scaling plaques on the trunk, buttock, and legs. Lesions are round or polycyclic and confluent forming geographic patterns. Although this is the classical manifestation of chronic stable plaque psoriasis, the eruption is still ongoing, as evidenced by the small guttate lesions in the lumbar and lower back area. This patient was cleared by acitretin/PUVA combination treatment within 4 weeks.
Skin Symptoms. Pruritus is reasonably common, especially in scalp and anogenital psoriasis.
Acute Guttate Type. Salmon-pink papules (guttate: Latin gutta, “drop”), 2.0 mm to 1.0 cm with or without scales (Figs. 3-1 and 3-2); scales may not be visible but become apparent upon scraping. Scales are lamellar, loose, and easily removed by scratching. Removal of scale results in the appearance of minute blood droplets (Auspitz sign). Scattered discrete lesions; generally on the trunk (Fig. 3-2); may resolve spontaneously; may become recurrent and evolve into chronic, stable psoriasis.
Chronic Stable Type. Sharply marginated, dull-red plaques with loosely adherent, lamellar, silvery-white scales (Fig. 3-3). Plaques coalesce to form polycyclic, geographic lesions (Fig. 3-4) and may partially regress, resulting in annular, serpiginous, and arciform patterns. Lamellar scaling can easily be removed, but when the lesion is extremely chronic, it adheres tightly resembling an oyster shell (Fig. 3-3).
Distribution and Predilection Sites
Acute Guttate. Disseminated, generalized, mainly trunk.
Chronic Stable. Single lesion or lesions localized to one or more predilection sites: elbows, knees, sacral gluteal region, scalp, and palm/soles (Fig. 3-5). Sometimes only regional involvement (scalp), often generalized.
Figure 3-5. Predilection sites of psoriasis.
Pattern. Bilateral, often symmetric (predilection sites, Fig. 3-5); often spares exposed areas.
Psoriasis in Skin of Color. In dark brown or black people psoriasis lacks the bright red color. Lesions are brown to black but otherwise their morphology is the same as in white skin (Fig. 3-6).
Figure 3-6. Confluent small psoriatic plaques in a 52-year-old female with HIV disease. She also had psoriatic arthritis. The lesions show less erythema than in Caucasian skin. Because the patient had been using emollients, no scale is noted.
Palms and Soles. May be the only areas involved. There is massive silvery white or yellowish hyperkeratosis, which is not easily removed (Fig. 3-7). The inflammatory plaque at the base is always sharply demarcated (Fig. 3-7A). There may be cracking, painful fissures and bleeding.
Scalp. Plaques, sharply marginated, with thick adherent scales (Fig. 3-8). Often very pruritic. Note: Psoriasis of the scalp does not lead to hair loss. Scalp psoriasis may be part of generalized psoriasis or the only site involved.
Figure 3-7. (A). Psoriasis, palmar involvement The entire palm is involved by large adherent scales with fissures. The base is erythematous and there is a sharp margin on the wrist. (B) Psoriasis vulgaris: soles Erythematous plaques with thick, yellowish, lamellar scale and desquamation on sites of pressure arising on the plantar feet. Note sharp demarcation of the inflammatory lesion on the arch of the foot. Similar lesions were present on the palms.
Figure 3-8. Psoriasis of the scalp There is massive compaction of horny material on the entire scalp. In some areas, the thick asbestos-like scales have been shed revealing a red infiltrated base. Alopecia is not due to psoriasis but is androgenetic alopecia.
Face. Uncommon but when involved, usually associated with a refractory type of psoriasis (Fig. 3-9).
Figure 3-9. Psoriasis, facial involvement Classic psoriatic plaque on the forehead of a 21-year-old male who also had massive scalp involvement.
Chronic Psoriasis of the Perianal and Genital Regions and of the Body Folds—Inverse Psoriasis. Due to the warm and moist environment in these regions, plaques usually not scaly but macerated, often bright red and fissured (Fig. 3-10). Sharp demarcation permits distinction from intertrigo, candidiasis, and contact dermatitis.
Figure 3-10. Psoriasis vulgaris: inverse pattern Because of the moist and warm environment in the submammary region, scales have been macerated and shed revealing a brightly erythematous and glistening base.
Nails. Fingernails and toenails frequently (25%) involved, especially with concomitant arthritis (Fig. 3-11). Nail changes include pitting, subungual hyperkeratosis, onycholysis, and yellowish-brown spots under the nail plate—the oil spot (pathognomonic).
Figure 3-11. Psoriasis of the fingernails Pits have progressed to elkonyxis (holes in the nail plates), and there is transverse and longitudinal ridging. This patient also has paronychial psoriasis and psoriatic arthritis (for further images of nail involvement, see Section 34).
Marked overall thickening of the epidermis (acanthosis) and thinning of epidermis over elongated dermal papillae. Increased mitosis of keratinocytes, fibroblasts, and endothelial cells. Parakeratotic hyperkeratosis (nuclei retained in the stratum corneum). Inflammatory cells in the dermis (lymphocytes and monocytes) and in the epidermis (lymphocytes and polymorphonuclear cells), forming microabscesses of Munro in the stratum corneum.
Serum. Increased antistreptolysin titer in acute guttate psoriasis with antecedent streptococcal infection. Sudden onset of psoriasis may be associated with HIV infection—do HIV serology. Serum uric acid is increased in 50% of patients, usually correlated with the extent of the disease; there is an increased risk of gouty arthritis.
Culture. Throat culture for group A β-hemolytic streptococcus infection.
Diagnosis and Differential Diagnosis
Diagnosis is made on clinical grounds.
Acute Guttate Psoriasis. Any maculopapular drug eruption, secondary syphilis, pityriasis rosea.
Small Scaling Plaques. Seborrheic dermatitis—may be indistinguishable from psoriasis. Lichen simplex chronicus. Psoriasiform drug eruptions—especially beta-blockers, gold, and methyldopa. Tinea corporis—KOH examination is mandatory, particularly in single lesions. Mycosis fungoides—Scaling plaques can be an initial stage of mycosis fungoides. Biopsy.
Large Geographic Plaques. Tinea corporis, mycosis fungoides.
Scalp Psoriasis. Seborrheic dermatitis, tinea capitis.
Inverse Psoriasis. Tinea, candidiasis, intertrigo, extramammary Paget disease. Glucagonoma syndrome—An important differential because this is a serious disease; the lesions look like inverse psoriasis. Langerhans cell histiocytosis (see Section 20), Hailey-Hailey disease (see page 92).
Nails. Onychomycosis. KOH is mandatory.
Course and Prognosis
Acute guttate psoriasis appears rapidly, a generalized “rash.” Sometimes this type of psoriasis disappears spontaneously in a few weeks without any treatment. More often evolves into chronic plaque psoriasis‘. This is stable and may undergo remission after months or years, recur, and be a lifelong companion.
Characterized by pustules, not papules, arising on normal or inflamed, erythematous skin. Two types.
Palmoplantar Pustulosis ICD-9: 696.1 ICD-10: L40.3
Incidence low as compared with psoriasis vulgaris.
A chronic relapsing eruption limited to palms and soles.
Numerous sterile, yellow; deep-seated pustules (Fig. 3-12) that evolve into dusky-red crusts.
Figure 3-12. Palmar pustulosis Creamy-yellow pustules that are partially confluent on the palm of a 28-year-old female. Pustules are sterile and pruritic, and when they get larger, become painful. At the time of this eruption, there was no other evidence of psoriasis anywhere else on the body, but 2 years later the patient developed chronic stable plaque psoriasis on the trunk.
Considered by some as localized pustular psoriasis (Barber-type) and by others a separate entity.
Generalized Acute Pustular Psoriasis (Von Zumbusch) ICD-9: 696.1 ICD-10: L40.1
A rare life-threatening medical problem with abrupt onset.
Burning, fiery-red erythema topped by pinpoint sterile yellow pustules in clusters spreading within hours over entire body. Coalescing lesions form “lakes” of pus (Fig. 3-13). Easily wiped off.
Figure 3-13. Generalized acute pustular psoriasis (von Zumbusch) This female patient was toxic and had fever and peripheral leukocytosis. The entire body was covered with showers of creamy-white coalescing pustules on a fiery-red base. Since these pustules are very superficial, they can be literally wiped off, which results in red oozing erosions.
Waves of pustules follow each other.
Fever, malaise, and leukocytosis.
Symptoms: burning, painful; patient appears frightened.
Onycholysis and shedding of nails; hair loss of the telogen defluvium type (see Section 33), 2-3 months later; circinate desquamation of tongue.
Pathogenesis unknown. Fever and leukocytosis result from release of cytokines and chemokines into circulation.
Differential diagnosis: pustular drug eruption (see Section 23); generalized HSV infection.
May follow, evolve, or be followed by psoriasis vulgaris.
Special types: Impetigo herpetiformis: generalized pustular psoriasis in pregnant woman with hypocalcemia. Annular type: in children with less constitutional symptoms (Fig. 3-14A), Psoriasis cum pustulatione (psoriasis vulgaris with pustulation: In maltreated psoriasis vulgaris. No constitutional symptoms. Acrodermatitis continua of Hallopeau: Chronic recurrent pustulation of nail folds, nail beds, and distal fingers leading to nail loss (Fig. 3-14B). Occurs alone or with generalized pustular psoriasis.
Figure 3-14. (A). Anular pustular psoriasis This occurs mainly in children and consists of expanding ring-like micropustular eruptions on a highly inflammatory base that is clear in the center and results in a collarette-like scaling at the margin. There is hardly any systemic toxicity. (B) Acrodermatitis continua of Hallopeau with acral pustule formation, subungual lakes of pus, and destruction of nail plates. This may lead to permanent loss of nails and scarring.
Psoriatic Erythroderma ICD-9: 696.1 ICD-10: L40
In this condition psoriasis involves the entire skin. See
Psoriatic Arthritis ICD-9: 696,0 ICD-10: L40.5
Seronegative. Psoriatic arthritis is included among the seronegative spondyloarthropathies, which include ankylosing spondylitis, enteropathic arthritis, and reactive arthritis.
Asymmetric peripheral joint involvement of upper extremities and especially distal interphalangeal joints. Dactylitis—sausage fingers (Fig. 3-15).
Figure 3-15. Psoriatic arthritis Dactylitis of index finger. Note sausage-like thickening over interphalangeal joints. There is psoriasis of the nail.
Axial form involves vertebral column, sacroiliitis.
Enthesitis: inflammation of ligament insertion into bone.
Mutilating with bone erosions, osteolysis, or ankylosis. Telescoping fingers. Functional impairment.
Often associated with psoriasis of nails (Figs. 3-11 and 3-15).
Associated with MHC class I antigens, while rheumatoid arthritis is associated with MHC class II antigens.
Incidence is 5-8%. Rare before age 20.
May be present (in 10% of individuals) without any visible psoriasis; if so, search for a family history.
Management of Psoriasis
Factors Influencing Selection of Treatment
1. Age: childhood, adolescence, young adulthood, middle age, >60 years.
2. Type of psoriasis: guttate, plaque, palmar and palmopustular, generalized pustular psoriasis, erythrodermic psoriasis.
3. Site and extent of involvement: localized to palms and soles, scalp, anogenital area, scattered plaques but <5% involvement; generalized and >30% involvement.
4. Previous treatment: ionizing radiation, systemic glucocorticoids, photochemotherapy (PUVA), cyclosporine (CS), and methotrexate (MTX).
5. Associated medical disorders (e.g., HIV disease).
Management of psoriasis is discussed in the context of types of psoriasis, sites, and extent of involvement. Psoriasis has to be managed by a dermatologist.
Localized Psoriasis (see Fig. 3-3)
• Topical fluorinated glucocorticoid covered with plastic wrap. Glucocorticoid-impregnated tape also useful. Beware of glucocosteroid side effects.
• Hydrocolloid dressing, left on for 24-48 h, is effective and prevents scratching.
• For small plaques (≤4 cm), triamcinolone acetonide aqueous suspension 3 mg/mL diluted with normal saline injected intradermally into lesions. Beware of hypopigmentation in skin of color.
• Topical anthralin also effective but can be irritant.
• Vitamin D analogues (calcipotriene, ointment and cream) are good nonsteroidal antipsoriatic topical agents but less effective than corticosteroids; they are not associated with cutaneous atrophy; can be combined with corticosteroids. Topical tacrolimus, 0.1%, similarly effective.
• Topical pimecrolimus, 1%, is effective in inverse psoriasis and seborrheic dermatitislike psoriasis of the face and ear canals.
• Tazarotene (a topical retinoid, 0.05 and 0.1% gel) has similar efficacy, best combined with class II topical glucocorticoids.
• All these topical treatments can be combined with 311-nm UVB phototherapy or PUVA.
Scalp. Superficial scaling and lacking thick plaques: Tar or ketoconazole shampoos followed by betamethasone valerate, 1% lotion; if refractory, clobetasol propionate, 0.05% scalp application. In thick, adherent plaques (Fig. 3-8): scales have to be removed by 10% salicylic acid in mineral oil, covered with a plastic cap and left on overnight before embarking on topical therapy. If this is unsuccessful, consider systemic treatment (see below).
Palms and Soles (Fig. 3-7). Occlusive dressings with class I topical glucocorticoids. If ineffective, PUVA either systemically or as PUVA soaks (immersion in 8-methoxypsoralen solution and subsequent UVA exposure). Retinoids (acitretin > isotretinoin), orally, removes the thick hyperkeratosis of the palms and soles; however, combination with topical glucocorticoids or PUVA (re-PUVA) is much more efficacious. Systemic treatments should be considered.
Palmoplantar Pustulosis (Fig 3-12). PUVA soaks and glucocorticosteroids are effective. Systemic treatment for recalcitrant cases. Inverse Psoriasis (Fig. 3-10) Topical glucocorticoids (caution: these are atrophy-prone regions; steroids should be applied for only limited periods of time); switch to topical vitamin D derivatives or tazarotene or topical tacrolimus or pimecrolimus. If resistant or recurrent, consider systemic therapy.
Nails (Fig. 3-11). Topical treatments of the fingernails are unsatisfactory. Systemic MTX and CS therapy effective but takes time and thus prone to side effects.
Acute, Guttate Psoriasis (Fig. 3-2). Treat streptococcal infection with antibiotics. Narrowband UVB irradiation most effective.
Generalized Plaque-Type Psoriasis (Fig. 3-4). PUVA or systemic treatments that are given as either mono—or combined—or rotational therapy. Combination therapy denotes the combination of two or more modalities, while rotational therapy denotes switching the patient after clearing and a subsequent relapse to another different treatment.
Narrowband UVB Phototherapy (311 nm). Effective only in thin plaques; effectiveness is increased by combination with topical glucocorticoids, vitamin D analogues, tazarotene, or topical tacrolimus/pimecrolimus.
Oral PUVA. Treatment consists of oral ingestion of 8-methoxypsoralen (8-MOP) (0.6 mg 8-MOP per kilogram body weight) or, in some European countries, 5-MOP (1.2 mg/kg body weight) and exposure to doses of UVA that are adjusted to the sensitivity of the patient. Most patients clear after 19-25 treatments, and the amount of UVA needed ranges from 100 to 245 J/cm2.
Long-Term Side Effects. PUVA keratoses and squamous cell carcinomas in some patients who receive an excessive number of treatments.
Oral Retinoids. Acitretin and isotretinoin are effective in inducing desquamation but only moderately effective in clearing psoriatic plaques. Highly effective when combined with 311-nm UVB or PUVA (called re-PUVA). The latter is in fact the most effective therapy to date for generalized plaque psoriasis.
Methotrexate Therapy. Oral MTX is one of the most effective treatments but response is slow and long-term treatment is required. Hepatic toxicity may occur after cumulative doses in normal persons (≥1.5 g).
The Triple-Dose (Weinstein) Regimen. Preferred by most over the single-dose MTX once weekly, 5 mg is given every 12 h for a total of three doses, i.e., 15 mg/week. Achieves an 80% improvement but total clearing only in some, and higher doses increase the risk of toxicity. Patients respond, the dose of MTX can be reduced by 2.5 mg periodically. Determine liver enzymes, complete blood count, and serum creatinine periodically. Be aware of the various drug interactions with MTX.
Cyclosporine1. CS treatment is highly effective at a dose of 3-5 mg/kg per day. If the patient responds, the dose is tapered to the lowest effective maintenance dose. Monitoring blood pressure and serum creatinine is mandatory because of the known nephrotoxicity of the drug. Watch out for drug interactions.
Monoclonal Antibodies and Fusion Proteins2 (so-called biologicals). Some of these proteins, specifically targeted to pathogenically relevant receptors on T cells or to cytokines, have been approved and more are being developed. They should be employed only by specifically trained dermatologists who are familiar with the dosage schedules, drug interactions, and short- or long-term side effects.
Alefacept is a human lymphocyte function-associated antigen (LFA)-3-IgG1 fusion protein that prevents interaction of LFA-3 and CD2. Given intramuscularly once weekly leads to considerable improvement and there may be long periods of remissions, but some patients do not respond.
Tumor Necrosis Factor-Alpha (TNF-α) antagonists that are effective in psoriasis are infliximab, adalimumab, and etanercept. Infliximab is a chimeric monoclonal antibody to TNF-α. Administered intravenously at weeks 0, 2, and 6, it is highly effective in psoriasis and psoriatic arthritis. Adalimumab is a fully human recombinant monoclonal antibody that specifically targets TNF-α. It is administered subcutaneously every other week and is similarly effective as infliximab. Etanercept is a human recombinant, soluble TNF-α receptor that neutralizes TNF-α activity. Administered subcutaneously twice weekly and is less effective than infliximab and adalimumab but is highly effective in psoriatic arthritis.
Ustekinumab (Anti-Interleukin (IL) 12/lnterleukin 23 p40) is a human IgG1K monoclonal antibody that binds to the common p40 subunit of human IL-12 and IL-23, preventing its interaction with its receptor. Given every 4 months subcutaneously, it is highly effective.
All these biologicals and others currently developed in clinical trials have side effects, and there are long-term safety concerns. Also, currently they are extremely expensive that limits their use in clinical practice. For doses, warnings, and side effects.2
Generalized Pustular Psoriasis (see Fig. 3-13)
These ill patients with generalized rash should be hospitalized and treated in the same manner as patients with extensive burns, toxic epidermal necrolysis, or exfoliative erythroderma—in a specialized unit. Isolation, fluid replacement, and repeated blood cultures are necessary. Rapid suppression and resolution of lesions is achieved by oral retinoids (acitretin, 50 mg/day). Supportive measures should include fluid intake, IV antibiotics to prevent septicemia, cardiac support, temperature control, topical lubricants, and antiseptic baths. Systemic glucocorticoids to be used only as rescue intervention as rapid tachyphylaxis occurs. Oral PUVA is effective, but logistics of treatment are usually prohibitive in a toxic patient with fever.
Acrodermatitis Continua Hallopeau
(Figure 3-14B) Oral retinoids as in von Zumbusch pustular psoriasis; MTX, once-a-week schedule, is the second-line choice.
Should be recognized early in order to prevent bony destruction. MTX, once-a-week schedule as outlined above; infliximab or etanercept are highly effective.
Pityriasis Rubra Pilaris (PRP) ICD-9: 696.4 ICD-10: L44.4
Rare, chronic, papulosquamous disorder often progressing to erythroderma.
Six types exist.
Follicular hyperkeratotic papules, reddish-orange progressing to generalized erythroderma. Sharply demarcated islands of unaffected (normal) skin.
Waxy, diffuse, orange keratoderma of palms and soles; nails may be affected.
Most effective therapy is MTX, systemic retinoids
Type 1: Classic Adult Generalized, beginning on head and neck.
Type 2: Atypical Adult Generalized, sparse hair.
Type 3: Classic Juvenile Appears within the first 2 years of life, generalized.
Type 4: Circumscribed Juvenile In prepubertal children, localized.
Type 5: Atypical Juvenile Onset in first few years of life, familial, generalized.
Type 6: HIV-Associated Generalized, associated with acne conglobata, hidradenitis suppurativa, and lichen spinulosus.
Rare. Affects both sexes and occurs in all races.
Etiology and Pathogenesis
Both insidious and rapid onset occur.
Skin Lesions. All types of PRP. An eruption of follicular hyperkeratotic papules of reddish-orange color usually spreading in a cephalocaudal direction (Fig. 3-16). Confluence to a reddish-orange psoriasiform, scaling dermatitis with sharply demarcated islands of unaffected skin (Fig. 3-37). In dark skin papules are brown (Fig. 3-18).
Figure 3-16. Pityriasis rubra pilaris (type 1, classic adult) Orange-red follicular papules beginning on the head and neck have coalesced on the chest of a 57-year-old male. There are sharply demarcated islands of unaffected normal skin.
Figure 3-17. Pityriasis rubra pilaris (type 1, classic adult) Orange-reddish papules have coalesced to near erythroderma, sparing isolated islands of normal skin. Also note involvement of the hands in this 55-year-old woman.
Figure 3-18. Pityriasis rubra pilaris in black skin Here papules do not have the classical orange color seen in Caucasians but are brown and therefore pose a diagnostic problem. Their shape and distribution and the areas of spared normal skin are diagnostic clues.
Distribution. Types 1, 2, 3, 5, and 6: Generalized, classically beginning on the head and neck, then spreading caudally. Progression to erythroderma (except for types 2 and 4).
Scalp and Hair. Scalp affected, as in psoriasis, often leading to asbestos-like accumulation of scale. Hair not affected except in type 2 where sparse scalp hair is observed.
Mucous Membranes. Spared.
Palms and Soles Pityriasis Pilaris (Type 1, Classic Adult). Palm shows diffuse, waxy, yellowish/orange hyperkeratosis (Fig. 3-19).
Figure 3-19. Pityriasis rubra pilaris on palms There is diffuse, waxy hyperkeratosis with an orange hue.
Nails. Common but not diagnostic. Distal yellow-brown discoloration, nail plate thickening, subungual hyperkeratosis, and splinter hemorrhages. See Section 34.
Associated Conditions. Ichthyosiform lesions on legs in type 2. Scleroderma-like appearance of hands and feet in type 5. Acne conglobata, hidradenitis suppurativa, and lichen spinulosus in type 6.
Diagnosis and Differential Diagnosis
The diagnosis is made on clinical grounds. The differential diagnosis includes psoriasis, follicular ichthyosis, erythrokeratodermia variabilis, and ichthyosiform erythrodermas.
Histopathology. Not diagnostic but suggestive: Hyperkeratosis, acanthosis with broad short rete ridges, alternating orthokeratosis, and parakeratosis. Keratinous plugs of follicular infundibula and perifollicular areas of parakeratosis. Prominent granular layer may distinguish PRP from psoriasis. Superficial perivascular lymphocytic infiltrate.
Course and Prognosis
A socially and psychologically disabling condition. Long duration; type 3 often resolves after 2 years; type 4 may clear. Type 5 has a very chronic course. Type 6 may respond to highly active antiretroviral therapy (HAART).
Topical therapies consist of emollients, keratolytic agents, vitamin D3 (calcipotriol), glucocorticoids, and vitamin A analogues (tazarotene). All are not very effective. Phototherapy (ultraviolet A phototherapy, narrowband ultraviolet B phototherapy, and photochemotherapy) is effective in some cases. Most effective treatment consists of systemic administration of MTX or retinoids (both as in psoriasis). In type 6: HAART. The anti-TNF agents, e.g., infliximab and etanercept are effective.
Pityriasis Rosea ICD-9:696.4 CD-10: L42
Pityriasis rosea is an acute exanthematous eruption with a distinctive morphology and often with a characteristic self-limited course.
Initially, a single (primary, or “herald”) plaque lesion develops, usually on the trunk; 1 or 2 weeks later a generalized secondary eruption develops in a typical distribution pattern.
The entire process remits spontaneously in 6 weeks.
Reactivation of human herpesvirus-7 (HHV-7) and HHV-6 is the most probable cause.
Epidemiology and Etiology
Age of Onset. 10-43 years, but can occur rarely in infants and old persons.
Season. Spring and fall.
Etiology. There is good evidence that pityriasis rosea is associated with reactivation of HHV-7 or HHV-6, two closely related β-herpesviruses.
Skin Lesions. Herald Patch. Occurs in 80% of patients, preceding exanthem. Oval, slightly raised plaque or patch 2-5 cm, salmon-red, fine collarette scale at periphery; may be multiple (Fig. 3-20A).
Figure 3-20. Pityriasis rosea (A). Herald patch. An erythematous (salmon-red) plaque with a collarette scale on the trailing edge of the advancing border. Collarette means that scale is attached at periphery and loose toward the center of the lesion. (B) Overview of exanthem of pityriasis rosea with the herald patch shown in part (A). There are papules and small plaques with oval configurations that follow the lines of cleavage. The fine scaling of the salmon-red papules cannot be seen at this magnification, while the collarette of the herald patch is obvious.
Exanthem. One to two weeks after herald patch. Fine scaling papules and patches with marginal collarette (Fig. 3-20B). Dull pink or tawny. Oval, scattered, with characteristic distribution following the lines of cleavage in a “Christmas tree” pattern (Fig. 3-21). Lesions usually confined to trunk and proximal aspects of the arms and legs. Rarely on face.
Figure 3-21. Pityriasis rosea Distribution “Christmas tree” pattern on the back.
Atypical Pityriasis Rosea. Lesions may be present only on the face and neck. The primary plaque may be absent, may be the sole manifestation of the disease, or may be multiple. Most confusing are the examples of pityriasis rosea with vesicles or simulating erythema multiforme. This usually results from irritation and sweating, often as a consequence of inadequate treatment (pityriasis rosea irritata).
Multiple Small Scaling Plaques. Drug eruptions (e.g., captopril and barbiturates), secondary syphilis (obtain serology), guttate psoriasis (no marginal collarette), small plaque parapsoriasis, erythema migrans with secondary lesions, erythema multiforme, and tinea corporis.
Dermatopathology. Patchy or diffuse parakeratosis, absence of granular layer, slight acanthosis, focal spongiosis, and microscopic vesicles. Occasional dyskeratotic cells with an eosinophilic homogeneous appearance. Edema of dermis and perivascular infiltrate of mono-nuclear cells.
Spontaneous remission in 6-12 weeks or less. Recurrences are uncommon.
Symptomatic. Oral antihistamines and/or topical antipruritic lotions for relief of pruritus. Topical glucocorticoids. May be improved by UVB phototherapy or natural sunlight exposure if treatment is begun in the first week of eruption. Short course of systemic glucocorticoids.
Parapsoriasis en Plaques (PP)
Rare eruptions with worldwide occurrence.
Two types are recognized: small-plaque PP (SPP) and large-plaque PP (LPP).
In SPP (ICD-9:696.2; ICD-10:L41.3), lesions are small (<5 cm), round to oval, or linear mostly on the trunk: “digitate dermatosis” (Fig. 3-22), slightly infiltrated, yellowish, or fawn-colored patches. Minimal scaling, asymptomatic, or mild pruritus.
Figure 3-22. Digitate dermatosis (small-plaque parapsoriasis) (A). The lesions are asymptomatic, yellowish or fawn-colored, very thin, well defined, slightly scaly and superficially wrinkled patches. They are oval and follow the lines of cleavage of the skin, giving the appearance of a “hug” that left fingerprints on the trunk. The long axis of these lesions often reaches more than 5 cm. (B) Close up of smaller lesions showing wrinkling of surface.
In LPP (ICD-9:692.2; ICD-10141.4), lesions are oval or irregularly shaped patches and >5 cm (Fig. 3-23). Minimal scaling, with and without atrophy. May be poikilodermatous.
Figure 3-23. Large-plaque parapsoriasis (parapsoriasis en plaques) (A) The lesions are asymptomatic, well-defined, rounded, slightly scaly, thin plaques, or patches. The lesions can be larger than 10 cm and are light red-brown or salmon-pink. There may be atrophy in some areas. The lesions here are located on the extremities, but they are more commonly noted on the trunk. These lesions must be carefully followed, and repeated biopsies are necessary to detect mycosis fungoides. This entity may be considered as a prestage of mycosis fungoides. (B) Close up of lesions showing minimal scaling and wrinkled surface.
SPP does not progress to mycosis fungoides (MF). LPP, by contrast, exists on a continuum with patch-stage MF and can progress to overt MF.
Treatment consists of topical glucocorticoids, phototherapy, narrowband 311-nm UV phototherapy, or PUVA.
Pityriasis Lichenoides (Acute and Chronic) (PL) ICD-9: 696.2 ICD-10:L41.0/L41.1
PL is an eruption of unknown etiology, characterized clinically by successive crops of a wide range of morphologic lesions.
Classified into an acute form, pityriasis lichenoides et varioliformis acuta (PLEVA), and a chronic form, pityriasis lichenoides chronica (PLC).
However, most patients have lesions of PLEVA and PLC simultaneously.
PLEVA is important because it can be mistaken for lymphomatoid papulosis (see Section 21).
More common in males than females, adolescents, and young adults.
Lesions tend to appear in crops over a period of weeks or months. Uncommonly, patients with an acute onset of the disorder may have symptoms of an acute infection with fever, malaise, and headache. Cutaneous lesions are usually asymptomatic but may be pruritic or sensitive to touch.
Lesions: PLEVA. Randomly arranged, most commonly on trunk, proximal extremities but also generalized, including palms and soles. Bright-red edematous papules (i.e., lichenoides), less commonly vesicles, which undergo central necrosis with hemorrhagic crusting (i.e., varioliformis, hence the designation PLEVA)
(Fig. 3-24A and B). PLC. This is the chronic form, scaling papules of reddish-brown color, and a central mica-like scale (Fig. 3-24C), Postinflammatory hypo- or hyperpigmentation often presents after lesions resolve. PLEVA may heal with depressed or elevated scars.
Figure 3-24. Pityriasis lichenoides et varioliformis acuta (PLEVA) (A) Randomly distributed red papules of different size, some of which show hemorrhagic crusting. In this 5-year-old child, the eruption appeared in crops over a period of 10 days. (B) PLEVA lesions in a 38-year-old Indonesian man. Lesions are more hyper-pigmented and there is considerable scaling and crusting. (C) Pityriasis lichenoides chronica (PLC) Discrete papules with fine mica-like scales that become more visible after slight scraping. In contrast to PLEVA, there is no hemorrhagic crusting.
Dermatopathology. Epidermis: spongiosis, keratinocyte necrosis, vesiculation, ulceration; exocytosis or erythrocytes within epidermis. Dermis: Edema, chronic inflammatory cell infiltrate in wedge shape extending to deep reticular dermis.
Clinical diagnosis is confirmed by skin biopsy. Differential diagnosis: varicella, guttate psoriasis, and lymphomatoid papulosis (which is clinically almost indistinguishable from PLEVA).
New lesions appear in successive crops. PLC tends to resolve spontaneously after 6-12 months. In some cases, relapses after many months or years.
Most patients do not require any therapeutic intervention. Oral erythromycin and tetracycline are effective in some cases. Ultraviolet radiation (whether natural sunlight or broadband UVB), 311-nm UVB, and PUVA are the treatments of choice if oral antibiotics fail after a 2-week trial.
1For details and drug interactions, see MJ Mihatsch, K Wolff. Consensus conference on cyclosporin A for psoriasis. Br J Dermatol. 1992;126:621.
2For details and drug interaction, see S Richardson, J Gelfand. In: Goldsmith L, Gilchrest B, Katz S, Paller A, Leffel D, Wolff K. eds. Fitzpatrick's Dermatology, in General Medicine. 8th ed. New York, NY: McGraw-Hill; 2013: pp 2814-2826.
3Griffiths WAD. Clin Exp Dermatol. 1980;5:105 and Gonzáles-López A et al. Br J Dermatol. 1999;140:931.