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discoid lupus (chronic cutaneous lupus erythematosus)
Discoid lupus refers to scarring skin rash.
Epidemiology:
1) age 20-45 years
2) females > males
3) possibly more severe in blacks
4) major cause of cutaneous lupus erythematosus
Pathology:
dermatopathology
1) epidermis: hyperkeratosis, atrophy, follicular plugging, liquefaction degeneration of the basal layer
2) strong PAS staining of thickened epidermal basement membrane
3) dermis: edema, dilation of small vessels, perifollicular infiltrate of lymphocytes & histiocytes
4) immunofluorescence
a) granular deposits of IgG > IgM at dermal-epidermal junction
b) active lesions not recently treated with glucocorticoids
c) negative in old lesions & normal skin (regardless of sun exposure): contrast to SLE where IgG deposits found in normal sun-exposed skin (70-80%) & non-exposed skin (50%)
Clinical manifestations:
1) atrophic depigmented & erythematous plaques with a surrounding rim of hyperpigmentation [7]
2) early lesions: sharply marginated papules & plaques with adherent scales on sun-exposed skin
3) late lesions:
a) atrophy & depression of lesions with slightly raised border
b) persistent localized erythema containing telangiectasias
c) adherent scales
d) follicular plugging
e) scarring, marked if untreated
4) active lesions are bright red (erythematous), old lesions may be pink, white or hyperpigmented (violaceous)
5) lesions generally asymptomatic, but may be slightly pruritic
6) sites of predilection: face & scalp, ears, dorsa of forearms, hands, fingers, toes, less frequently trunk
7) scarring alopecia [5]
8) duration of lesions months to years
9) < 5% have mucous membrane involvement
10) not associated with systemic lupus erythematosus, thus may be few if any manifestations of systemic lupus [2]
11) nasolabial folds may not be spared [2]
* images [3,4,6,7]
Laboratory:
1) anti-nuclear antibody in serum
- low incidence of ANA in low titer 1:16
2) complete blood count (CBC): occasional leukopenia
3) skin biopsy
4) urinalysis (rule-out systemic lupus erythematosus with renal involvement)
Complications:
- 5-15% risk of systemic lupus erythematosus
Differential diagnosis:
1) actinic keratosis
2) psoriasis
3) polymorphous light eruption
4) lichen planus
5) lupus vulgaris (systemic lupus erythematosus with discoid lesions)
6) tinea facialis
7) alopecia areata (complete loss of hair, no visible effect on skin) [8]
Management:
1) topical corticosteroids
2) intralesional triamcinolone acetonide 3-5 mg/mL
3) topical tacrolimus, topical pimecrolimus
4) hydroxychloroquine 100 mg PO QD, up to 6.5 mg/kg/day, plus (if needed) quinacrine hydrochloride 100 mg PO QD
- some evidence that hydroxychloroquine may prevent progression to systemic lupus erythematosus [2]
5) etretinate 1 mg/kg/day (severe discoid lupus)
6) anifrolumab (investigational)
7) prevention:
- topical sunscreens (SPF 30 or higher)
- protective clothing
8) prognosis:
a) only 5-10% may develop SLE [2]
b) complete remisson in 50%
c) remissions less frequent with generalized lesions (<10%)
Specific
lupus panniculitis (lupus erythematosus profundus)
General
cutaneous lupus erythematosus
References
- Color Atlas & Synopsis of Clinical Dermatology, Common
& Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY,
1997, pg 352-55
- Medical Knowledge Self Assessment Program (MKSAP) 11, 15, 17, 18.
American College of Physicians, Philadelphia 1998, 2009, 2015, 2018
- Eastham ABW, James WD (images)
Medscape: Discoid Lupus Erythematosus
http://emedicine.medscape.com/article/1065529-overview
- DermNet NZ. Cutaneous lupus erythematosus (images)
http://www.dermnetnz.org/immune/cutaneous-lupus.html
- Hordinsky M
Cicatricial alopecia: discoid lupus erythematosus.
Dermatol Ther. 2008 Jul-Aug;21(4):245-8
PMID: 18715293
- Elston CA, Elston MD
Identifying Lesions on Skin of Color.
Medscape. 2021. May 10
https://reference.medscape.com/slideshow/identifying-lesions-6007985
- Elston CA, Elston DM
Identifying Lesions on Skin of Color.
Medscape. October 25, 2022
https://reference.medscape.com/slideshow/identifying-lesions-6007985
- NEJM Knowledge+ Dermatology