Pemphigus erythematosus is considered to be a variant of pemphigus foliaceus that includes features of systemic lupus erythematosus in its clinical presentation. Blistering lesions that are typical for all subtypes of pemphigus exhibit a characteristic "butterfly" pattern of appearance on the face, together with a seborrheic erythematous rash. The diagnosis is made on clinical grounds and identifying deposition of immunoglobulins along the basement membrane and intercellular membrane.
Pemphigus erythematosus (also known as Senear-Usher syndrome, named after the two authors who first described the disease) is a rather conspicuous disorder that exhibits clinical manifestations of two illnesses - pemphigus foliaceus (a blistering autoimmune disease in which intercellular glycoproteins desmoglein-1 are a target of immunoglobulin (Ig) G) and systemic lupus erythematosus (SLE)   . For this reason, some authors interpret pemphigus erythematosus as a disorder carrying multiple autoimmune mechanisms of pathogenesis . The clinical presentation of pemphigus erythematosus is comprised of small vesicles and bullae that exhibit a "butterfly pattern" of distribution on the face (the cheeks and the nose, as well as the nasolabial folds and preauricular areas), which is typical for erythematous lesions seen in SLE that may be concomitantly present  . Lesions are also distributed on the scalp, the upper chest, and the back, with some authors hypothesizing that the location of lesions is somehow related to sun exposure  . The erythematous base of blistering lesions is visible upon their rupture, while signs of yellowish crusting and scaling are frequently observed . An important distinguishing feature of pemphigus erythematosus (and pemphigus foliaceus) from pemphigus vulgaris is the absence of lesions on the mucosal surfaces (the vulva and the oral cavity) .
A meticulous clinical, immunological, and histological workup is necessary in order to make the diagnosis of pemphigus erythematosus. The role of a proper physical examination is perhaps of essential importance in recognizing the spectrum of lesions that may suggest either pemphigus or systemic lupus erythematosus. Their distribution and stage (blisters, plaques, scales, crusts, etc.) should be carefully assessed, after which immediate sampling of the lesion and subsequent histological examination is recommended. To distinguish between different forms of pemphigus, the bullae in pemphigus erythematosus stem in the more superficial levels of the epidermis (just below the stratum corneum), while bullae in pemphigus vulgaris and pemphigus vegetans arise in more deep layers of the skin (just above the stratum basale) . To establish a firm diagnosis, however, immunofluorescent antibody testing is the gold standard. The pemphigus group (including pemphigus foliaceus and pemphigus erythematosus) exhibits intercellular space staining of keratinocytes on immunofluorescence (due to antibody attachment to desmoglein-1) , but concomitant acantholysis and accumulation of immunoglobulins in desmosomes and at the dermal-epidermal junction along the basement membrane (also known as the lupus band test) is a unique feature of pemphigus erythematosus   . Furthermore, serological testing for antinuclear antibodies (ANAs) are positive in a significant number of cases, thus proving the concomitant presence of systemic lupus erythematosus .