Table 1 Clinical and Histological features of Stevens-Johnson syndrome (SJS) and subacute cutaneous lupus erythematosus (SCLE)

Clinical features

• Mostly drug-related

• May be idiopathic or drug-induced

Although the rapidity and severity of symptom progression favored a working diagnosis of SJS, on clinical grounds it was not possible to distinguish between SJS and SCLE in the case presented

• Characterized as dusky erythematous lesions; lesions tend to be isolated but can have confluence on the face and trunk

• Characterized as erythematous, papulosquamous or polycyclic annular plaques, typically non-scarring

• Typically involves the trunk, back, and extremities including palms and soles, neck, and face; often associated with painful mucosal surfaces

• Typically consists of photosensitive regions with lesions confined to sun-exposed skin (upper trunk/back, shoulders, extensor arms, neck, lateral aspects of face) with mid-facial sparing

• Usually occurs within 7 to 21 days after initiation of the causative drug

• Latent period between drug administration and the appearance of symptoms can range from several weeks to several years (in drug-induced SCLE)

Histological features

• In early lesions, apoptotic keratinocytes are observed scattered in the supra-basal layers of the epidermis

• Epidermal changes and a superficial lymphocytic infiltrate in the upper dermis with apoptotic keratinocytes

Histological findings of an interface dermatitis with dermal mucin deposition is most consistent with a diagnosis of SCLE

• In late stages, a sub-epidermal blister with overlying confluent necrosis of the entire epidermis and spare peri-vascular infiltrate composed primarily of lymphocytes is seen

• Dermal mucin deposits are commonly identified