Derm Dx: Erythematous, Scaly Scalp Lesions

The term lupus, which is Latin for wolf, dates back to the 10th century, when it was first used to describe aggressive skin lesions resembling a wolf's bite. Later, lupus was found to be a multisystem autoimmune disease with numerous...

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The term lupus, which is Latin for wolf, dates back to the 10th century, when it was first used to describe aggressive skin lesions resembling a wolf’s bite. Later, lupus was found to be a multisystem autoimmune disease with numerous diverse symptoms. Lupus erythematosus (LE) can be categorized as systemic lupus erythematosus (SLE) or cutaneous lupus erythematosus (CLE). CLE is further differentiated into acute (ACLE), subacute (SCLE), and chronic (CCLE) subtypes.^1,2

Discoid lupus erythematosus (DLE) is the most common subtype of CCLE. Discoid lupus accounts for the majority of CLE skin lesions (80%), followed by SCLE (15%).¹ DLE most commonly affects women in the third or fourth decade of life and is seen most frequently in African American individuals; however, it is also seen in a multitude of ethnic groups.^1,3,4

Lupus erythematosus involves a group of illnesses caused by autoimmunity to self antigens (nucleosomes and ribonucleoproteins).⁵ Cutaneous disease can exist independently or with systemic disease. Simply, one can think of LE on a spectrum: mild disease may manifest only with discoid skin lesions, and severe disease may manifest with severe systemic manifestations such as nephritis and vasculitis. Of the cutaneous lupus subtypes, ACLE is nearly always associated with visceral involvement, SCLE meets SLE criteria in approximately 50% of cases, and CCLE usually presents with skin-only or skin-predominant disease. Fortunately, only 5% to 10% of patients with DLE lupus will go on to develop SLE. Still, discoid lupus is often disfiguring and permanent, and can significantly affect a patient’s quality of life.³

Discoid rashes most often affect sun-exposed areas, including the face, scalp, ears, neck, upper chest, and extensor surfaces of the arms. Occasionally, the rash can present as a symmetric, hyperkeratotic, butterfly-shaped plaque across the malar areas of the face and the bridge of the nose. Less often, it presents as a generalized discoid rash with cutaneous involvement above and below the neck.^1,3,6 In its early form, DLE is characterized by erythematous macules or papules that rapidly grow and coalesce into hyperkeratotic plaques. Classically, early DLE lesions grow into larger indurated, round plaques with peripheral scale that eventually progress to become atrophic scars. When DLE lesions expand, they develop erythema and hyperpigmentation at the periphery, with atrophic scarring, hypopigmentation, and telangiectasia in the center. Thus, DLE lesions are more notable in darker-skinned individuals. When expanding, DLE lesions can also merge, forming confluent and disfiguring plaques. DLE lesions can affect hair-bearing regions such as the scalp and eyebrows, causing a scarring alopecia. Extension of lesions into hair follicles, also known as follicular plugging, is a classic finding associated with DLE lesions. Keratin can accumulate in the hair follicle; when peeled back, a keratotic spike seen under the scaly surface is known as the carpet-tack sign.^1,6

The differential diagnosis for discoid lupus includes basal cell carcinoma, actinic keratosis, lichen planus, tinea faciei, secondary syphilis, sarcoidosis, cutaneous tuberculosis, leprosy, scars, and other subtypes of CLE such as SCLE.¹ As DLC classically presents as a coin-shaped plaque with hyperpigmented or erythematous borders and central scarring, these features help to differentiate it from other diseases.

As mentioned, hyperkeratosis and extension into hair follicles is common. The most frequent locations for DLE presentation include the face, scalp, and ears.^3,7 Early active lesions of DLE look similar to other subtypes of CLE, such as ACLE and SCLE. However, induration is more common in DLE and can be useful in differentiating it from other subtypes of CLE.⁸

The diagnosis of cutaneous lupus is often made in the context of known underlying SLE. Skin biopsy confirms the diagnosis. Histopathology of CLE is similar across many subtypes; therefore, although helpful in diagnosis of DLE, it is not definitive. Some shared histopathologic findings in CLE include hyperkeratosis, thickening of the basement membrane, follicular damage, leukocytic infiltration, interface dermatitis, liquefactive damage to the basal cell layer, and deep dermal involvement. Of those listed, findings more suggestive of DLE than other CLE subtypes include hyperkeratosis, follicular plugging, and basement membrane thickening. Direct immunofluorescence and antibodies have unclear value in confirming the diagnosis. In direct immunofluorescence, granular deposits of immunoglobulins and complement may be visualized along the basement membrane zone in lesions. However, these findings are not unique to LE and can be found in other skin disorders. In addition, these findings are only positive in sun-involved skin; therefore, immunofluorescence in sun-protected skin will almost always be negative in patients with DLE.^1,8

There is no cure for discoid lupus, but multiple therapies are available for symptom management. Initial management requires ruling out systemic involvement. Patients should be advised to discontinue smoking and limit sun exposure with both broad-spectrum sunscreen and wearing sun-protective clothing to avoid triggers. They should also be instructed to avoid drugs that cause photosensitivity such as tetracycline, griseofulvin, hydrochlorothiazide, and piroxicam. First-line medical therapies include high-potency topical corticosteroids, intralesional corticosteroids applied to active lesions monthly, and topical calcineurin inhibitors. Hydroxychloroquine and acitretin have also been shown to have approximately 50% efficacy in treatment of cutaneous lupus and should be considered in those with systemic symptoms.^3,9,10  In patients with refractory symptoms, second-line  therapies such as retinoids, methotrexate, thalidomide, mycophenolate, azathioprine, and dapsone have shown some efficacy.^2,10

The patient in the case described above was diagnosed with discoid lupus and was advised to limit sun exposure. Treatment with hydroxychloroquine and intralesional corticosteroids applied to his scalp lesions was initiated monthly. At 3-month follow-up, notable regression of the lesions was noted.

Joy Tan, BS, is a medical student; Talia Noorily, BA, is a medical student; and Christopher Rizk, MD, is a dermatology fellow at Baylor College of Medicine, Houston, Texas.

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References

1. Grönhagen CM, Nyberg F. Cutaneous lupus erythematosus: an update. Indian Dermatol Online J. 2014;5(1):7-13.
2. Sontheimer RD, Thomas JR, Gilliam JN. Subacute cutaneous lupus erythematosus: a cutaneous marker for a distinct lupus erythematosus subset. Arch Dermatol. 1979;115(12):1409-1415.
3. Costner MI, Sontheimer RD. Lupus erythematosus. In: Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, Wolff K. eds. Fitzpatrick’s Dermatology in General Medicine, 8^th ed. New York, NY: McGraw-Hill; 2012.
4. Lateef A, Petri M. Unmet medical needs in systemic lupus erythematosus. Arthritis Res Ther. 2012;14(Suppl 4):S4.
5. Janeway CA, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease.  5^th ed. New York: Garland Science; 2001.
6. Cardinali C, Caproni M, Bernacchi E, Amato L, Fabbri P. The spectrum of cutaneous manifestations in lupus erythematosus-the Italian experience. Lupus. 2000;9(6):417-423.
7. Obermoser G, Sontheimer RD, Zelger B. Overview of common, rare and atypical manifestations of cutaneous lupus erythematosus and histopathological correlates. Lupus. 2010; 19(9):1050-1070.
8. Haber JS, Merola JF, Werth VP. Classifying discoid lupus erythematosus: background, gaps, and difficulties. Int J Womens Dermatol. 2017;3(1 Suppl):S62-S66.
9. Sontheimer RD. Skin manifestations of systemic autoimmune connective tissue disease: diagnostics and therapeutics. Best Pract Res Clin Rheumatol. 2004;18(3):429-462.
10. Jessop S, Whitelaw DA, Grainge MJ, Jayasekera P. Drugs for discoid lupus erythematosus. Cochrane Database Syst Rev. 2017:CD002954.