Case 1 History
The patient is an 81-year-old female with multiple superficial erosions involving the head and upper trunk.
Histopathology
Microscopy reveals an intraepidermal rift with separation of the stratum corneum and upper epidermis from the lower epidermis. Associated acantholysis is noted. A sparse mixed infiltrate is present ( Fig. 4.1 ).
Diagnosis
Pemphigus Foliaceus
Pemphigus foliaceus is characterized by subcorneal acantholysis caused by autoantibodies to desmoglein-1. The resultant vesicles and bulla typically spare mucosal surfaces, in contrast to pemphigus vulgaris, and rupture easily.
Clinical Presentation
Pemphigus foliaceus presents as small vesicles that readily rupture, which eventuates in shallow erosions on the face, scalp, back, and chest. The onset is commonly in adulthood. An endemic form (fogo selvagem) presents in younger patients in South America. Pemphigus erythematosus represents pemphigus foliaceus presenting concurrently with facial involvement similar to that of lupus erythematosus.
Histopathology
Acantholysis of the epidermis in pemphigus foliaceus is centered on the stratum granulosum, and thus intraepidermal rifts or separation of the stratum corneum from the remainder of the epidermis may occur. Adnexal acantholysis may also be present. A mixed infiltrate that includes eosinophils, neutrophils, or both is typical of all subtypes of pemphigus, and intraepidermal granulocytes (representing so-called eosinophilic spongiosis or neutrophilic spongiosis) can be seen in areas of early involvement. Direct immunofluorescence (DIF) microscopy confirms the presence of immunoglobulin (Ig) G and complement component C3 in an intracellular distribution. In pemphigus erythematosus, junctional deposition of immunoreactants can also be seen.
Differential Diagnosis
The differential diagnosis includes bullous impetigo, staphylococcal scalded skin syndrome (SSSS), and subcorneal pustular dermatosis ( Table 4.1 ).
| Pemphigus Foliaceus | Impetigo or SSSS | Subcorneal Pustular Dermatitis | |
|---|---|---|---|
| Pathophysiology | Autoantibodies to desmoglein-1 | Exotoxin cleaves desmoglein-1 | Presumably similar to psoriasis |
| Characteristic histopathologic feature | Subcorneal acantholysis | Subcorneal acantholysis | Subcorneal pustules |
| Infiltrate | Mixed infiltrate with neutrophils and eosinophils | Mixed infiltrate with neutrophils (impetigo only) | Mixed infiltrate with neutrophils |
Bullous Impetigo
Impetigo represents a superficial infection with associated secondary acantholysis.
Clinical Presentation
The infection commonly involves the face. Small pustules may be associated with honey-colored crust. There may be associated hyperemia.
Histopathology
Microscopically, intraepidermal neutrophils are associated with superficial acantholysis ( Fig. 4.2 ). There may be concomitant spongiosis. The associated dermal infiltrate commonly includes both lymphocytes and neutrophils. Identifying bacteria using Gram staining represents the key to establishing the diagnosis. Acantholysis is triggered by bacterial exotoxin produced in conjunction with local infection.
Staphylococcal Scalded Skin Syndrome
Clinical Presentation
SSSS (Ritter disease) presents in infants with fever, irritability, and erythema that progresses to flaccid blisters. The disease is rare in patients older than age 6 years. Blistering is often perioral or involves flexural surfaces.
Histopathology
The histopathologic findings of SSSS are attributable to toxin-mediated acantholysis. Similar to impetigo, an exotoxin is produced by staphylococcal infection, but infection involves a remote site. Because the disease is toxin mediated with an absence of local infection, the histopathologic appearance may be completely or largely noninflammatory. Acantholysis involving the outer epidermis may be associated with a sparse mixed secondary inflammatory infiltrate.
Subcorneal Pustular Dermatitis (Sneddon-Wilkinson Disease)
Clinical Presentation
Subcorneal pustular dermatitis represents a subtype of pustular psoriasis. The eruption not uncommonly presents in annular fashion.
Histopathology
Biopsies of subcorneal pustular dermatitis demonstrate sterile subcorneal pustules with spongiform pustular morphology ( Fig. 4.3 ). There may be scant surface parakeratosis, and a superficial lymphohistiocytic infiltrate with neutrophils is common. Subcorneal pustular dermatitis is not an acantholytic disorder, and DIF microscopy is typically negative for immunoreactant deposition.
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Pemphigus foliaceus
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Fragile superficial blisters that often spare mucosal surfaces
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Subcorneal acantholysis
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Bullous impetigo or SSSS
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Infection with crust or erythema
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Subcorneal acantholysis
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Subcorneal pustular dermatosis
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Nonpruritic flaccid pustules
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Subcorneal spongiform pustules without acantholysis
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Case 2 History
The patient is a 30-year-old female presents with recurrent erosions in the bilateral axilla and inframammary area.
Microscopic Findings
Sections show hyperkeratosis, acanthosis, and acantholysis involving the majority of the spinous layer of the epidermis ( Fig. 4.4 ).
