1.2.1 Lupus Erythematosus

Lupus erythematosus, discoid LE, systemic LE.

Usually affects young adults 20-40 years of age; F:M = 3:1, in systemic lupus erythematosus 8:1. 

Immunogenetic susceptibility (HLA associations).

Polyclonal B-cell activation with autoantibody formation: direct pathogenic antibodies (autoimmune haemolytic anaemia), circulating immune complexes (vasculitis, nephritis), antibody-mediated cytotoxicity (skin lesions).

Precipitating factors: UV, medications, oestrogens (oral contraceptives, pregnancy), possibly some viruses, trauma (Koebner phenomenon), possible stress.

In discoid lupus erythematosus persistent several mm to cm sharply bordered, sometimes confluent, and painful lesions with triad of erythema, follicular keratotic plugs, and atrophy (each of which can dominate clinical picture). In systemic LE butterfly rash. Non- specific changes include erythematous maculopapular exanthema, diffuse hair loss, Raynaud syndrome, livedo racemosa (anticardiolipin antibodies and others) as a sign of cutaneous vasculitis, can all be present.

Usually light-exposed areas, especially face, nose, ears, checks (butterfly rash), scalp.

Chronic cutaneous lupus erythematosus 
(Synonym:  chronic discoid LE (DLE)

Coin or disk-shaped erythematous plaques with follicular hyperkeratosis and a tendency to heal with scarring, usually on light-exposed areas or scalp (acquired, circumscribed scarring alopecia).

Variants:

• Hypertrophic LE (verrucosus LE)
• Disseminated DLE
• Chilblain LE (acral involvement)
• Lupus profundus/lupus panniculitis (deeper involvement) 

Subacute cutaneous LE (SCLE)

Non-scarring, polycyclic-annular or papulosquamous (psoriasiform) plaques which usually involve the upper half of the body and are clearly light-provoked. Systemic symptoms (arthritis, fever, malaise) are milder than in SLE (severe CNS or renal disease rare).

Systemic LE (SLE)

ACR (American College of Rheumatology) criteria:

1. Butterfly rash (acute cutaneous LE)
2. Discoid lesions
3. Photosensitivity
4. Oral ulcerations
5. Non-erosive arthritis
6. Serositis: pleuritis; pericarditis
7. Neurologic disease: seizures; psychosis
8. Renal disease (proteinuria >0.5g/d, cellular casts)
9. Hematologic abnormalities (hemolytic anemia, leukopenia
10. ANA
11. anti-dsDNS, anti-Sm, false positive syphilis serology >6 months (for example, with anticardiolipin antibodies) 

Most of the skin findings of DLE and SCLE can be found in SLE.

The diagnosis is based on >= 4 ACR being fulfilled. Other non-specific skin changes: Raynaud's syndrome, diffuse alopecia, vascultis/vasculopathy, maculopapular and other exanthems.

CCLE: ANA in 25-60% (often low titers); anti-dsDNA negative; complement factors C3, C4 normal.

SCLE: With active disease erythrocyte sedimentation rate elevated , anti-SSA (Ro) 70-90%, anti-dsDNA 30-40%, rheumatoid factor (RF) 20%, leukopenia (lymphopenia).

SLE: Normo-hypochromic anemia, leukopenia, thrombocytopenia, C-reactive protein and sedimentation rate elevated, anti-native-DNA (40-90%), anti-U1-RNP (40-60%), anti-SSA (Ro) (40-60%), anti-histone (70%), RF 30%, anti-cardiolipin antibodies (false positive syphilis serology).

CCLE: Epidermal atrophy, hyperkeratosis (primarily follicular), vacuolar degeneration of basal keratinocytes, thickened basement membrane zone (PAS stain), edema, dense lymphocytic perivascular and periadnexal infiltrate at all levels, and, including subcutaneous fat in lupus profundus.

In SCLE and SLE milder and less characteristic histologic changes, but lymphomononuclear infiltrate surrounding the capillaries and some vacuolisation at the BMZ. Incontinence of melanin pigment.

Direct immunofluorescence examination: identification of granular band of C3- and IgG along the epidermal-dermal junction in lesional skin; in SLE also in sun-exposed normal skin (lupus band test).

Pure cutaneous disease usually chronic with hypopigmentation and scarring, especially when discoid. Systemic disease takes highly variable course, ranging from mild disease to acute, life-threatening disease, especially with renal, cardiac or central nervous system involvement.

Depends on systemic involvement (CNS lupus, lupus nephritis).
Rarely squamous cell carcinoma (lupus carcinoma) develops in old DLE scars.

Clinical features (using ACR criteria);

Immune serology (autoantibody profile);

Histology;

Direct immunofluorescence.

DLE: psoriasis, tinea, other photodermatoses.

SCLE:  psoriasis, tinea, pityriasis rosea, syphilis, other photodermatoses.

SLE: Depending on pattern of systemic involvement, other multisystem diseases, such as rheumatoid arthritis, dermatomyositis or mixed connective tissue diseases.

CCLE and SCLE: antimalarials (hydroxychloroquine, chloroquine), can be combined with low-dose corticosteroids, light protection; in SCLE: thalidomide off-label.

SLE: multidisciplinary management adjusted to organ involvement (antimalarials, systemic immunosuppression with corticosteroids and immunosuppressive agents such as azathioprine, cyclophosphamide, biologicals: belimumab and ustekinumab).

Self-help groups.