Psoriasis and Other Papulosquamous Diseases

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[edit] Psoriasis and Other Papulosquamous Diseases

James C. Shaw

Frank Parker

The combination of papules and scales are the common features of papulosquamous skin diseases. The term squamous refers to scaling that represents thick stratum corneum and thus implies an abnormal keratinization process. In addition to unusual scales, lesions are characterized by sharply demarcated, red to violaceous papules and plaques that result from thickening of the epidermis or underlying dermal inflammation. The sharp delineation of the lesions in this group of diseases helps distinguish them from scaling lesions of eczematous diseases where the borders are usually indistinct (with two exceptions—nummular eczema and seborrheic dermatitis) (Box 85-1).

[edit] PSORIASIS

[edit] Epidemiology and Pathophysiology

The exact cause of psoriasis is unknown, but it appears to be a multifactorial disease with genetic influences and immune regulation.^[1] The worldwide prevalence is 3%, with a 1% prevalence in North America. Onset can be at any age. Family history of psoriasis is found in about 40% of patients, and gene studies have shown linkage to several HLA loci.

The psoriasis phenotype is manifested by increased epidermal cell turnover (decreased turnover time), increased numbers of epidermal stem cells, and abnormal differentiation of keratin expression leading to thickened skin with copious scale. Immune regulation appears to be the largest influence of the abnormal phenotype, with numerous cytokines and growth factors required, and striking clinical improvement with immunomodulatory therapies (see Management section). Precipitating factors can trigger or worsen psoriasis. These include streptococcal infections, overuse of ethanol, psychologic stress, certain medications (beta blockers, lithium), and trauma to the skin (inducing the Koebner phenomenon, where new skin lesions evolve in areas of injury to the skin).

[edit] Patient Evaluation

[edit] History.

The onset and course of the disease are highly variable. It usually begins gradually, confined to a few areas, but it can be explosive in onset. One cause of the latter presentation is a preceding streptococcal throat infection, which leads in 2 to 3 weeks to multiple, small guttate lesions generalized over the body. Once the disease appears, it follows an irregular, chronic, and unpredictable course. It may remain localized to a few areas or may cause intermittent or continuous generalized lesions.

Itching is usually not a problem in psoriasis but may be severe in individual patients.

[edit] Physical Examination.

The lesions are erythematous papules and plaques surmounted by thick, silvery scales that resemble mica (micaceous) and that are not easily removed and often accumulate in the patient's clothing or bed (see Plate 3 ). When the scales are traumatically removed, multiple small bleeding sites appear (Auspitz's sign). In intertriginous areas, maceration and moisture prevent dry scales from accumulating, but the lesions remain red and sharply defined (inverse psoriasis) ( Plate 26 ).

Lesions usually are distributed symmetrically over areas of body prominence such as elbows and knees. They also frequently occur on the trunk, penis ( Plate 27 ), scalp, and intergluteal cleft and umbilicus. Nail involvement may include stippling or pitting of the nail plate or yellow or red-brown coloring (“oil-staining”) of onycholytic patches with accumulation of yellow debris under nails ( Plate 28 ). Psoriatic arthritis, occurring in less than one-third of patients with psoriasis, commonly presents with red, swollen distal interphalangeal joints and nail involvement.

[edit] Diagnosis

[edit] Laboratory Studies and Diagnostic Procedure.

A skin biopsy can substantiate the diagnosis but is seldom necessary because the clinical features of psoriasis are so distinctive. No serologic or other diagnostic tests are available.

[edit] Differential Diagnosis.

See Table 85-1.

Table 85-1 Differential Diagnosis of Psoriasis

[edit] Management

There are now numerous treatments available, both topical and systemic. Although there is no cure for the disease, considerable improvement can be achieved with well-selected treatments.

[edit] Nonpharmacologic Therapy.

Avoidance of excessive alcohol consumption may benefit some patients. Many patients improve in the summer months on the basis of sun exposure, which can be recommended with caution. Soaking baths to remove scale, followed by liberal emollient use is also helpful. Stress reduction programs may help prevent exacerbations in some patients.

[edit] Topical Pharmacologic Therapy

[edit] Corticosteroids.

Class I steroid ointments are a mainstay of psoriasis treatment and can be used as a short course therapy twice a day followed by a class III steroid for maintenance. On the face, only class VI or VII should be used. On the scalp, class I solutions are best, along with a medicated shampoo containing tar, selenium sulfide, or ketoconazole.

[edit] Tar.

Coal tar is frequently added to a topical corticosteroid regimen. A 2% to 5% crude coal tar (CCT) compounded with the steroid, although messy, can be helpful.

[edit] Calcipotriol.

Calcipotriol is a vitamin D derivative (calcipotriene, Dovonex) that affects keratinocyte differentiation. It has been successful when used twice a day on psoriasis plaques.^[2] Recently, the combined use of calcipotriol and a class I corticosteroid has shown to be effective when used for a limited time to induce remission of plaques.

[edit] Topical Retinoids.

The newest form of topical therapy in psoriasis is tazarotene, a topical retinoid that affects keratinocyte differentiation. Successful outcomes have been shown with once daily application. Tazarotene has been used in combination with ultraviolet light therapy.^[3] Some irritation of the skin can be reduced with concomitant use of corticosteroids.

[edit] Ultraviolet Light Therapy.

Treatment with ultraviolet B (UVB) and oral psoralen plus ultraviolet A (PUVA) are possibly the most successful of the nonsystemic therapies in psoriasis. Details of these treatments are beyond the scope of this text, but light therapy should be considered in any patient with widespread disease involving more than 20% of the skin surface.

[edit] Systemic Therapies

[edit] Methotrexate.

Low doses of methotrexate given weekly have been used in widespread psoriasis or psoriatic arthritis for the last 25 years. The effect of methotrexate on T-lymphocytes appears to be responsible for the effect. Monitoring for side effects, including bone marrow suppression and liver disease, is essential when using this modality.

[edit] Systemic Retinoids.

Acetretin (a metabolite of etretinate, its predecessor) is highly effective in selected patients with widespread disease, including those with severe pustular forms of psoriasis. Concerns about teratogenicity limit its use in women.

[edit] Cyclosporine.

Another immune modulator with considerable success in psoriasis is cyclosporin A, which can be considered in severe disease. Monitoring of blood pressure, renal function, and blood levels is required.

[edit] Special Patients and Issues

Guttate psoriasis in the young patient should initiate a search for streptococcal pharyngitis.^[4] The patient often is asymptomatic after a day or two of throat soreness. Antibiotic therapy and eradication of the streptococcus may induce a remission of the psoriasis.

[edit] Reiter's Syndrome

Reiter's syndrome ( Plate 29 ) can be readily confused with psoriasis because the skin lesions of the two disorders are indistinguishable clinically and histologically. In Reiter's disease, pustular and keratotic papules and plaques commonly occur on the palms and soles (keratoderma blennorrhagicum) and scaling, red patches are found encircling the glans penis and within the groin (balanitis circinata). Other features of Reiter's syndrome may include a seronegative, asymmetric arthritis that may involve the sacroiliac joints, as well as uveitis, conjunctivitis, and mucous membrane lesions. The presence of asymptomatic erosions on the tongue and buccal mucosa, urethritis, and occasionally diarrhea distinguish Reiter's syndrome from psoriasis.

[edit] PITYRIASIS ROSEA

[edit] Epidemiology and Etiology

Pityriasis rosea is a self-limited papulosquamous eruption that occurs in young adults. A possible viral etiology has been suggested because of the increased incidence in the winter months and because patients report a history of a preceding upper respiratory infection.

[edit] Physical Examination

Oval or round, tan-, ink-, or salmon-colored, scaling papules and plaques appear rapidly over the trunk, neck, upper arms, and thighs (see Plate 8 ). Several features of this papulosquamous condition are unique. First, the generalized eruption is preceded by a single lesion, termed the herald patch, that is commonly misdiagnosed as tinea corporis. The herald patch can occur anywhere but often appears on the neck or lower trunk and precedes the general rash by several days to a week. Second, the oval patches have an unusual fine, white scale located near the border of the plaques, forming a collarette ( Plate 30 ). Third, the lesions follow skin cleavage lines, with the long axis paralleling these lines in a Christmas tree pattern (see Plate 8 ).

[edit] Differential Diagnosis

Drug eruption and secondary syphilis must be considered in the differential diagnosis. If the rash persists beyond 3 months or generalizes to involve the extremities and face, a drug reaction should be considered (e.g., gold compounds, barbiturates, captopril, clonidine). Serologic tests for syphilis should be obtained if the rash involves the palms and soles and if fever, coryza, or mucous membrane erosions (mucous patches) are present.

[edit] Management

Treatment may not be necessary, although topical corticosteroids and antihistamines relieve itching and decrease erythema. Ultraviolet light (UVB) given as three to five treatments to give a mild erythema reaction often clears the rash.

[edit] LICHEN PLANUS

[edit] Epidemiology and Pathophysiology

Lichen planus is a chronic, pruritic, papulosquamous disease with a wide range of clinical manifestations. Lichen planus is considered an immune response to one or more antigenic stimuli. The association with infection with hepatitis C virus (HCV) has given increased importance to making the diagnosis of lichen planus.

[edit] Physical Examination

Lichen planus is included in the papulosquamous group of diseases because the primary lesion is a unique papule with an unusual surface configuration. The papules are flat topped (planus) and polygonal in configuration (i.e., the sides conform to normal fine skin folds and creases) and have a lilac or purple hue ( Plate 31 ). They may have visible scales on their surface, but more characteristic are subtle, fine, white reticulated lines (Wickham's striae) surmounting the shiny flat tops of the papules (resembling lichen). Wickham's striae become more apparent under a hand lens after the application of a drop of mineral oil on the surface of the papules. Typical distribution is symmetric papules on the ankles, flexural wrists, mouth, and genitalia. Although the condition is extremely pruritic, one seldom sees excoriations or erosions induced by scratching. Mucous membranes are commonly involved, the lesions appearing most often as asymptomatic white streaks in a reticulate pattern on the buccal mucosa, tongue, gums, or lips ( Plate 32 ). At times, blisters and erosions are superimposed on the mucous membrane areas (erosive lichen planus), causing severe discomfort.

[edit] Differential Diagnosis

See Table 85-2.

Table 85-2 Differential Diagnoses of Lichen Planus-like Skin Conditions

[edit] Management

Since up to 20% of patients with lichen planus have antibodies to HCV (compared to 2.4% of controls in a study from Spain), screening of all patients for HCV infection may be indicated.^[5] Treatment is nonspecific and not always successful. For localized patches, topical steroids of the moderate to potent forms may be useful in suppressing the itching and inflammation. If the disease is widespread, a 4-to 6-week course of oral corticosteroids may reverse the course (40 to 60 mg/day) with tapering. Erosive oral lichen planus is particularly difficult to control, but at times intralesional steroid injections are helpful. Patients with widespread lichen planus or erosive painful oral lichen planus should be referred for dermatologic consultation.

[edit] SEBORRHEIC DERMATITIS

[edit] Etiology

The cause of seborrheic dermatitis is not known; but overgrowth of a normally occurring yeast, Pityrosporum ovale, may play some role. The disorder is also possibly genetically determined, although its mode of inheritance is not clear.

[edit] Pathophysiology

Seborrheic dermatitis is an inflammatory scaling reaction that occurs in seborrheic areas of the skin (areas where large numbers of sebaceous glands are found, e.g., scalp, ears, head, and chest). Dandruff is merely a mild form of seborrheic dermatitis in the scalp.

[edit] History

In adults, the process can involve only the scalp or may also cause an erythematous, greasy, scaling rash in the nasolabial folds, eyebrows, beard area, external ears, and presternal areas. Blepharitis is also a manifestation. At times, stress may cause exacerbation of the condition. Seborrheic dermatitis is often one of the earliest cutaneous signs of human immunodeficiency virus (HIV) infection.

[edit] Physical Examination and Clinical Features

Ill-defined, erythematous patches with greasy yellow scales are typical of seborrheic dermatitis. They may or may not be pruritic. The location of the lesions is often the most important factor in diagnosing this condition; locations include scalp, retroauricular, external ears, eyebrows, nasolabial folds, presternal, and, at times, axillae, and groin ( Plate 33 ).

Seborrheic dermatitis associated with HIV infection is often extensive and difficult to control. For reasons not clear, seborrheic dermatitis is common and often severe in patients with chronic neurologic conditions such as Parkinson's disease, cerebrovascular accident and spinal cord injuries. At times, it is difficult to distinguish seborrheic dermatitis from psoriasis; some patients appear to have both conditions.

[edit] Diagnosis

[edit] Differential Diagnosis.

The differential diagnoses in adults include psoriasis, Reiter's disease, and atopic dermatitis.

[edit] Laboratory Evaluation.

There are no specific diagnostic tests, although biopsy can distinguish between typical psoriasis and seborrheic dermatitis.

[edit] Management

Shampoos containing tar, sulfur, salicylic acid, ketoconazole, or selenium, if used daily on a prolonged basis, often control scalp and face lesions (when the shampoo is applied to these areas as well). Hydrocortisone cream 1% to 2.5% applied once or twice a day controls lesions on the ears and face. More potent topical steroids in solution form (flucinolone 0.01%) are useful in controlling scalp lesions when medicated shampoos do not provide complete clearing.

[edit] PITYRIASIS RUBRA PILARIS

Pityriasis rubra pilaris (PRP) is a rare papulosquamous disorder of keratinization. Its cause is unknown, although there are cases of familial PRP, as well as the more common sporadic cases. Clinical findings include widespread orange-red plaques that can involve the entire skin surface area, frequently with small islands of totally normal skin (“island sparing”), thickening of the palms and soles into a waxy keratotic shell, and in early stages, follicular accentuation. Treatment is with short courses of high-dose vitamin A (up to 300,000 IU/day), but frequently the disease is resistant to all therapies.

[edit] SYPHILIS

Secondary syphilis frequently presents with skin lesions that fit the category of papulosquamous diseases. Multiple, raised papules or small plaques with some scale are typical. The disease can resemble pityriasis rosea closely. Clues to suggest syphilis include involvement of palms and soles; lesions in inguinal, gluteal, axillary, or mucosal areas; scalp involvement with patchy alopecia; and a supportive sexual history. Serology and skin biopsy can help confirm the diagnosis. See Chapter 29 for management of syphilis.

[edit] REFERENCES