| • | AKA “superficial pemphigus” or "seborrheic pemphigus" |
| • | blistering in this group is high in the epidermis either in the granular layer or just beneath the stratum corneum |
4 subsets:
| • | cutaneous lesions similar in all subsets |
| • | identical immunopathologic features |
| • | arise in unique circumstances |
| • | AKA Senear-Usher syndrome |
| • | overlap features of both diseases: |
| • | butterfly rash, photosensitivity/ trunk lesions similar to pemphigus foliaceus |
| ◆ | granular IgG and C3 at the basement membrane zone/ intercellular IgG and C3 in epidermis |
| • | ANA+ but rarely progresses to systemic LE |
| • | may be associated with myasthenia gravis |
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| 3. | drug induced pemphigus foliaceus |
| 4. | fogo selvagem (wild fire) |
| • | endemic pemphigus foliaceus |
| • | common in rural parts of South America, particularly certain states in Brazil |
| • | possible vector = black fly |
Clinical:
| • | less severe than pemphigus vulgaris |
| • | onset is insidious with scattered, scaly lesions involving the “seborrheic areas” (scalp, face, chest, and upper back) |
| • | blistering may not be obvious because superficial blisters rupture |
| • | oral lesion uncommon (desmoglein 1 not expressed on mucosal epithelium??) |
| • | ddx: seborrheic dermatitis, impetigo, DH |
Histology:
| • | split within or just beneath the granular layer |
Pathogenesis:
| • | desmoglein I (a 165kDa desmosomal cadherin) |
| • | mnemonic: “First time you need a foley is when you are 65” |
| • | PF antigens are expressed more strongly in skin from upper torso than in specimens from lower torso, buccal mucosa or scalp |
IgA pemphigus foliaceus
| • | a rare vesicular pustular disorder |
| • | clinically, most closely resembles pemphigus foliaceus or subcorneal pustular dermatosis |
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