PH is rare, with approximately 100 cases reported in the literature, typically manifesting in middle-aged adults as an intensely pruritic cutaneous eruption with herpetiform clusters of vesicles. PH rarely affects children, with fewer than 10 reported cases in the literature. No ethnic or sex predilections have been observed.
The inciting factors of the disease include generation of immunoglobulin G (IgG) autoantibodies that recognize desmoglein 1 (less commonly, desmoglein 3 or desmocollin 1 or 3) on keratinocytes, stimulating upregulation of interleukin-8, which serves as a chemoattractant for eosinophils and neutrophils. In turn, these inflammatory cells secrete proteases that mediate eosinophilic or neutrophilic spongiosis and blister formation.
Unlike the classical pemphigus disorders, PH usually exhibits a benign clinical course. However, cases of PH progressing to PF or PV have been reported.
PH has been rarely reported to be associated with internal malignancies, most commonly lung cancer, but PH has been reported with various other cancers (eg, esophageal cancer and cutaneous angiosarcomas). Association with other inflammatory / autoimmune conditions and infections have been reported, including psoriasis, systemic lupus erythematosus, autoimmune hemolytic anemia, and HIV infection.
L10.89 – Other pemphigus
771145006 – Herpetiform pemphigus
Differential Diagnosis & Pitfalls
- Dermatitis herpetiformis – History of gluten-sensitive enteropathy. Can differentiate with histopathological survey and immunofluorescence studies, as well as serologic testing.
- Pemphigus foliaceus (PF) – Clinical appearance of PH resembles dermatitis herpetiformis more so than PF.
- Pemphigus vulgaris (PV) – Clinical appearance of PH resembles dermatitis herpetiformis more so than PV. Lesions of PV tend to be painful, in contrast to the nontender, pruritic lesions of PH. PV commonly involves the mucous membranes, which are often spared in PH.
- Bullous pemphigoid – Differentiate with histopathological survey and immunofluorescence studies.
- Linear IgA bullous dermatosis – Differentiate with histopathological survey and immunofluorescence studies.
- IgA pemphigus – Differentiate with histopathological survey and immunofluorescence studies.
- Bullous systemic lupus erythematosus – Differentiate with histopathological findings and immunofluorescence studies.
- Allergic contact dermatitis (ACD) – Differentiate clinically (ACD is typically limited to the site of contact allergen exposure, although generalized ACD can be seen) and by negative immunofluorescence studies in allergic contact dermatitis.