What is the differential?
Our patient had bullous pemphigoid. Pemphigoid is an autoimmune blistering skin disease. It is different from pemphigus which is also autoimmune but the skin cleaves within the epidermis making the skin very fragile causing sloughing with minor trauma (Nikolsky’s sign) In pemphigoid the blisters are often firm and resist tearing .
It is the result of an attack on the basement membrane of the epidermis by immunoglobulins and activated T lymphocytes. The target is the protein BP180(also called Type XVII collagen) The protein is found in hemidesmosomes, structures the connect the dermis to the epidermis. The binding of antibodies to the hemidesmosomes destroys them and subepidermal blisters form.
The disease is more prevalent in elderly patients. It can be triggered by drugs or malignancy. It is also more common in people with underlying skin disease like psoriasis.
The differential for blistering diseases is broad.
AUTOIMMUNE- pemphigoid, and dermatitis herpetiformis (caused by gluten sensitivity), linear IgA dermatosis, eczema
INFECTIOUS -varicella, herpes, atypical enterovirus infection, necrotising fasciitis, erysipelas. Reactions to infection like erythema multiforme and staphylococcal scalded skin syndrome also cause blistering .
DRUGS-Stevens Johnson, fixed drug eruption , drug hypersensitivity syndrome.
CONTACT ALLERGIES- poison ivy, cold exposure
METABOLIC CAUSES- porphyria cutanea tarda (an abnormality in heme production)
GENETIC CAUSES- epidermolysis bullosa ( a genetic disease resulting in blistering. Gene therapy has been successfully used in treating this disease in a seven year old boy in Germany. In skin cells from a non blistered area stem cells were extracted, treated with a virus containing a correct copy of the LAMB3 gene , and grown into sheets which were used to cover his body. Blistering has not reoccurred in the grafted areas.
The treatment for bullous pemphigoid is generally steroids which our patient received.
In 2015 a seven year old boy was treated for epidermolysis bullosa with gene therapy. The patient’s cells contained a mutation in the LAMB3gene which affects a protein needed to strengthen the epidermi
Wojnarowska F ,Kitschig G, et al. Guidelines for the management of bullous pemphigoid. 2002 Br J Dermatol 147(2) 214-21.
Schmidt E, Zillikens D. The diagnosis and treatment of autoimmune blistering skin diseases. Dtsch Arztebl Int 2011 . 108(23):399-405