Background
The clinical features of bullous pemphigoid are extremely polymorphous and its cutaneous manifestations protean. Several atypical forms of bullous pemphigoid have been described, and the diagnosis critically relies on immunopathologic findings.  
Objective
The purpose of the study was to describe a new variant of bullous pemphigoid characterized by diffuse hyperkeratosis and palmo-plantar keratoderma with high IgE levels, that we named hyperkeratotic bullous pemphigoid.
Methods
We performed a case-series study. Five patients fulfilled the diagnostic criteria of bullous pemphigoid. We evaluated the severity of the disease using the ABSIS score. We used commercial ELISAs to detect IgG and IgE anti-BP180 and anti-BP230 antibodies.
Results
We described five hyperkeratotic bullous pemphigoid patients with palmo-plantar keratoderma, diffuse hyperkeratotic cutaneous lesions, and extremely high total IgE levels. Some of these patients presented a resistant bullous pemphigoid, which required multiple systemic treatments.
Conclusion
The diagnosis of hyperkeratotic bullous pemphigoid should be taken into account in patients presenting diffuse hyperkeratotic cutaneous lesions and palmo-plantar keratoderma, even in the absence of blisters, as this clinical variant is likely to pose additional challenges in the choice of an effective treatment regimen.

Hyperkeratotic bullous pemphigoid: 5 cases of a new clinical subset.