Antibodies to pilosebaceous units along their neurovascular supply routes in a new variant of endemic pemphigus foliaceus in Colombia, South America.

Senear Usher syndrome is a variant of pemphigus foliaceus, confined to seborrheic sites and considered to be a clinical overlap syndrome, with features of both pemphigus foliaceus and lupus erythematosus. We recently described autoantibodies to skin eyelid meibomian glands in patients with a new variant of endemic pemphigus foliaceus (El Bagre EPF) in South America. We tested for El Bagre EPF patient sera autoreactivity to pilosebaceous units utilizing direct and indirect immunofluorescence, confocal microscopy, immunohistochemistry and immunoelectron microscopy. Hematoxylin and eosin staining of skin biopsies revealed that one third of the patients affected by El Bagre-EPF demonstrated some histologic alteration of the pilosebaceous units. By immunohistochemistry, most El Bagre EPF biopsies demonstrated evidence of an autoimmune response along the neural and vascular supply routes of the pilosebaceous units. An active immune response was seen with antibodies such as anti-human mast cell tryptase, myeloid/histoid antigen, CD8, CD20, CD68, CD117/c-kit, ZAP-70 and vimentin. Immunoelectron microscopy demonstrated autoantibodies within the hair follicle and at the basement membrane area of the sebaceous glands. El Bagre-EPF patients have autoantibodies to pilosebaceous units and to their surrounding neurovascular packages. Our results warrant further characterization and may explain the loss of hair described in severe endemic pemphigus foliaceus before the therapeutic steroid era.