Mildly pruritic elbow and knee plaques


  • CA0511DermClin_1

A girl aged 12 years presented with a six-month history of enlarging red plaques on bilateral elbows and knees. She was otherwise healthy and had no history of recent infections.

The lesions were associated with mild pruritus, which was not keeping her up at night. There was no family history of atopic dermatitis, allergic rhinitis, or asthma. No prior treatments had been attempted.

On physical examination, erythematous plaques, some with fine silvery scale, were noted on bilateral elbows and knees. No nail changes were seen. 

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Plaque psoriasis Psoriasis and leprosy are two separate disease entities that were classified as dry, scaly eruptions and grouped together by Hippocrates and his school around 400 b.c.1 These conditions were even written about in the Old Testament. During that...

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Plaque psoriasis

Psoriasis and leprosy are two separate disease entities that were classified as dry, scaly eruptions and grouped together by Hippocrates and his school around 400 b.c.1 These conditions were even written about in the Old Testament. During that time and for a period thereafter, many psoriatics were isolated from their community and church, at times even ordered to be burned at the stake. It was not until 1809 that Robert Willan gave an accurate description of psoriasis, recognizing it as an entity distinct from leprosy.1

Worldwide, the prevalence of psoriasis is 2%. Nail involvement has been reported in 79% of psoriatic patients, and arthritis is seen in 5%-30% of patients.2 Psoriasis can appear at any age; however, there are two main peaks of onset: one during the third to fourth decades and another during the sixth to seventh decades, with 75% of patients presenting before age 45 years.1,3

Psoriasis seems to be triggered by external and systemic factors in genetically susceptible individuals. The Koebner phenomenon is an external triggering factor in which psoriatic lesions develop at sites of previous cutaneous injury. This phenomenon is present in approximately 25% of patieints.1 Systemic factors include infections (most commonly streptococcal, especially pharyngitis), HIV, endocrine disorders, stress, medications, alcohol consumption, smoking, and obesity.

Chronic plaque psoriasis is the most common variant. Sharply demarcated, erythematous plaques with overlying fine silvery scale are characteristic. Less often, many small papules and plaques are seen diffusely (guttate psoriasis) or on nearly the entire body (erythrodermic psoriasis). Pustules may also be present in generalized pustular psoriasis and pustulosis of the palms and soles. Plaques are symmetrical and most often occur on the scalp, knees, elbows, pre-sacrum region, and hands and feet.1 In about 30% of patients, the genitalia may be involved.1

Other special locations to be affected by psoriasis include the flexural regions, oral mucosa, and nails. Facial psoriasis is most commonly seen in children, although it does occur in adults as well.4 The plaques of facial psoriasis may show an annular configuration and are more clearly delineated than atopic dermatitis plaques.5 They are most commonly found on the periorbital area and nasolabial folds.

Psoriasis is a chronic disease with a waxing and waning course. During exacerbations, psoriatic lesions may be associated with pruritus. Pinpoint papules surrounding a psoriatic plaque or an active edge with intense eyrthema are signs of an unstable phase of the disease. As the lesions begin to resolve, the center is the first to clear, resulting in annular psoriatic lesions. Resolution of the lesions may result in hypo- or hyperpigmentation.

Histologically, the epidermis shows confluent para­keratosis and hypogranulosis. The epidermis shows regular acanthosis (rete ridges appear to be the same length) and club-shaped rete ridges.6 Suprapapillary thinning of the epidermis and dilated capillaries in the dermal papillae are distinguishing features.7 These dilated capillaries are often the cause of Auspitz sign—punctate bleeding when the scale is removed. Neutrophils may be present in the stratum corneum and spinous layer. Perivascular lymphocytes may be seen in the dermis.

The differential diagnosis includes seborrheic dermatitis, lichen simplex chronicus, tinea corporis, psoriasiform drug eruptions, pityriasis rosea, mycosis fungoides, and the most commonly confused entity, atopic dermatitis. Health-care providers should ask about a family history of asthma, allergic rhinitis, and atopic dermatitis to help distinguish between the two. Biopsy may be necessary to definitively diagnose psoriasis if the lesions are not clinically characteristic.

There are numerous treatment choices for psoriasis. However, there are no definitive cures; only management options. Long-term management requires personalized therapy and thought from the clinician regarding the extent and severity of the individual’s disease. Avoiding short-term fixes and focusing on long-term solutions is the best course of action. Up to 40% of individuals are not happy with their treatment.4

For lesions located on the body, first-line therapy is a medium- to high-potency fluorinated corticosteroid cream or ointment. In general, ointments are more effective than creams on psoriasis plaques. Topical corticosteroids ointments may be used in combination with a vitamin D3 analogue, topical retinoid, anthralin, or tar. Approximately 80% of patients treated with high-potency topical corticosteroids experience clearance, usually within two weeks.4 For areas in the scalp, a gel or foam vehicle is often used. Monotherapy for flexural or facial psoriasis may include a mild topical corticosteroid or topical calcineurin inhibitors. Photochemotherapy, methotrexate, cyclosporine, systemic retinoids, and biologic therapies are also options, depending on the severity of the disease.

Unfortunately, psoriasis is a disease of the immune system; this means people who develop it will have it for life. The best course of action for patients with psoriasis is to establish care with a clinician and work together to form a treatment plan with which the patient agrees to comply, hopefully improving quality of life.

This patient’s mild plaque psoriasis and was treated with clobetasol 0.05% ointment, applied twice daily for two weeks to affected areas on the body. Clearance was achieved, and the regimen is currently repeated during flares only.

Kerri Robbins, MD, is a resident in the department of dermatology at Baylor College of Medicine in Houston. The author has no relationships to disclose relating to the content of this article.

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1. JL Bolognia, JL Jorizzo, RP Rapini, eds. Dermatology, 2nd ed., St. Louis, Mo.: Mosby-Elsevier; 2008:115-135.

2. de Jong EM, Seegers BA, Gulinck MK, et al. Psoriasis of the nails associated with disability in a large number of patients: results of a recent interview with 1,728 patients. Dermatology. 1996;193:300-303.

3. Christophers E. Psoriasis—epidemiology and clinical spectrum. Clin Exp Dermatol. 2001;26:314-320.

4. Paller AS, Mancini AJ. Hurwitz Clinical Pediatric Dermatology. 3rd ed. Philadelphia, Pa.: Elsevier Saunders; 2006:85-94.

5. Morris A, Rogers M, Fischer G, Williams K. Childhood psoriasis: a clinical review of 1262 cases. Pediatr Dermatol. 2001;18:188-198.

6. RP Rapini. Practical Dermatopathology. Philadelphia, Pa.: Elsevier-Mosby; 2005:51-53.

7. DE Elder, R Elenitsas, BL Johnson, et al, eds. Lever’s Histopathology of the Skin. 10th ed., Philadelphia, Pa.: Lippincott Williams & Wilkins; 2009: 174-181.

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