Localized (i.e., malar rash, butterfly rash)

Generalized/Disseminated (morbilliform)

82% photosensitivity^†

Transient (lasting from hours to weeks) and often occurs after sun exposure

Resolves without scarring

Localized: mild erythematous to intense edema extending across the midface region and nasal bridge and sparing the nasolabial fold

Generalized: maculopapular rash

Vacuolar interface dermatitis with keratinocyte necrosis

Superficial lymphohistiocytic infiltrate at the dermal-epidermal junction

Dermal mucin deposition [17]

Toxic epidermal necrolysis (TEN)-like ACLE

Erythema multiforme or TEN appearing eruption in pre-existing ACLE or SCLE lesions. With erythema multiforme (EM)-like presentation (also known as Rowell syndrome), lesions have a targetoid appearance, and with TEN presentation (also referred to as acute syndrome of apoptotic pan-epidermolysis or ASAP), there is diffuse erythema and Nikolsky sign (sloughing of the skin upon lateral pressure)

Full-thickness epidermal necrosis; otherwise, histologic features are similar to those above [18]

Annular

Psoriasiform/Papulosquamous

Drug-induced (DI)-SCLE

76% photosensitivity^†

Resolves without scarring

Annular: polycyclic plaques configuration with raised red border and central clearing

Psoriasiform: hyperkeratotic plaques potentially imitating psoriasis vulgaris

Localized: affects sun-exposed areas and shows a pattern of photodistribution

• i.

  Sides of the face affected, and the central facial skin is usually unaffected

• ii.

  V of the neck

• iii.

  Extensors of the upper extremity

The drug-induced form may have a strong association with Ro/SS-A autoantibodies

Similar histologic features to discoid lupus (see below), but often shows

• i.

  A greater degree of epidermal atrophy and necrotic keratinocytes

• ii.

  Less prominent hyperkeratosis, follicular plugging, and minimal to absent basement membrane zone thickening [17, 19]

DI-SCLE histologic features are similar to those observed in other forms of SCLE [20, 21]

DI-SCLE may be histologically indistinguishable from idiopathic SCLE, requiring strong clinicopathologic correlation for accurate diagnosis. The presence of leukocytoclastic vasculitis, however, may favor DI-SCLE

Vesiculobullous annular

Vesiculobullous annular (also called bullous lupus): bullous or vesicular lesions corresponding to intense inflammation along the basement membrane; sometimes anti-basement membrane antibodies are found, which may represent a concurrent presentation of bullous pemphigoid or epidermolysis bullosa acquisita in systemic lupus erythematosus (SLE).

Distinguishing features include a subepidermal blister with neutrophils in the papillary dermis and perivascular chronic inflammatory infiltrate

Analysis of dermal mucin deposition, direct IF studies, and clinicopathologic correlation analysis may help to differentiate this form of LE from other subepidermal blistering conditions [22, 23]

Neonatal LE

Polycyclic papulosquamous lesions in neonates driven by transplacental transfer of maternal antibodies

Histologic features are similar to those observed in other forms of SCLE [24]

Less common variants:

• i.

  Erythrodermic

• ii.

  Poikilodermatous

• iii.

  EM-like (Rowell syndrome)

• iv.

  Vesiculobullous annular SCLE

Rowell syndrome: target-like erythematous plaques imitating erythema exsudativum multiforme

Histologic features are similar to those observed in other forms of SCLE [18, 25, 26]

Discoid LE (DLE)

• i.

  Localized DLE

• ii.

  Generalized DLE

• iii.

  Hypertrophic/Verrucous DLE

• iv.

  Mucosal DLE

46% photosensitivity^†

Lesions begin as flat or slightly elevated, sharply demarcated, red macules or papules with a scaly surface

Later, hyperkeratotic, central scarring plaques appear, with hyperpigmentation, alopecia in scalp lesions

Common locations:

• i.

  Face, scalp, ears, and conchal bowl

Vacuolar interface dermatitis with dense pandermal perivascular and peri-appendageal lymphocytic inflammation

Follicular hyperkeratosis/plugging

Variable epidermal atrophy or epidermal hyperplasia, and scarring

Dermal mucin deposition

Thickening of the basement membrane zone [27, 28]

LE tumidus

63% photosensitivity^†

Violaceous or erythematous edematous papules and plaques in sun-exposed areas

Lesions have erythema and induration but lack scaling and follicular plugging

Common locations of lesions:

• i.

  Face, upper trunk/upper chest, and upper arms

Single or multiple lesions

Dense perivascular and peri-adnexal lymphocytic inflammatory infiltrate with abundant dermal mucin deposition

Distinguishing features include a lack of significant vacuolar interface dermatitis and follicular plugging.

Does not show prominent basement membrane zone thickening [29]

May appear histologically identical to Jessner lymphocytic infiltration of the skin

Lupus profundus (also known as lupus panniculitis)

0% photosensitivity^†

Intense inflammation in the fat leads to indurated plaques that can evolve into disfiguring, depressed areas

Retracted atrophic lesions mainly over proximal extremities and with a distinctive distribution predominantly on the face, upper arms, upper trunk, breasts, buttocks, and thighs

Lobular panniculitis with lymphoid follicles containing reactive germinal centers, clusters of B lymphocytes and plasmacytoid dendritic cells, mixed cell infiltrate with plasma cells, and polyclonal T-cell receptor y gene rearrangements

Dermal mucin deposition, +/– vacuolar interface dermatitis [30–32]

Chilblain LE/Perniosis LE

0% photosensitivity^†

Tender erythematous lumps in acral areas

Acral, dusky to purple plaques that worsen in cold temperatures

Dense dermal perivascular lymphocytic infiltrate, erythrocyte extravasation, and variable fibrin deposits within vessels (lymphocytic vasculitis)

Papillary dermal edema

May show vacuolar interface dermatitis [33, 34]

LE/Lichen planus overlap

Lichenoid CLE-lichen planus overlap syndrome (LE-LP overlap syndrome)

Overlap syndrome, in which one or more of the clinical, histological, and immunopathological features of both LE and LP are present [35]

Mainly painful, bluish-red plaques with atrophy and scaling, and hyperkeratotic papules and nodules predominantly on the extremities

Erythematous/Violaceous plaques and papules with scaling, overlapping histological features of CLE and LP, with or without serological markers

Red or dusky purple papules and plaques on the following:

• i.

  Toes, fingers, and sometimes the nose, elbows, knees, and lower legs

Lesions are brought on or exacerbated by cold temperatures and moisture

It may be difficult to distinguish by light microscopy alone; however, some authors have reported a double-layer indirect IF technique using patient serum and autologous lesional skin as substrates to establish the correct diagnosis [36]

Comedogenic LE

Comedogenic LE: a rare variant of chronic cutaneous lupus with comedones and inflammatory papules, and plaques resembling acne vulgaris, and also leading to scarring. Notably, discoid lupus lesions can also present with comedonal lesions, particularly in the ears

Histologic features are not well documented in the literature; however, this subtype is reported to feature dilated follicles with prominent follicular plugging [37]