How does the skin blister and why does it happen?
The formation of a blister is a localized deposition of fluid, most commonly deep to the epidermis, the most superficial layer of skin. Blistering can occur due to a direct insult to the skin such as friction, an acute temperature injury to the skin or due to direct chemical exposure. Indirect influences can also cause localized blistering including allergic reactions to antigens such as a bee sting, allergic reaction or illness.
What causes blistering?
Blistering is an acute release of interstitial fluid that is part of an inflammatory cascade that:
- Stops bleeding
- Attracts mast cells and platelets that release histamine
- Clears injured cells from the wound site
- Generates new skin to resurface the injury
One unique and sometimes serious cause of blistering that occurs secondary to an immune reaction is called pemphigus vulgaris. Pemphigus vulgaris forms a fluid-filled blister that often has an erosive base, blistering deep into the deeper layers of skin, called the dermis. Pemphigus vulgaris is due to an autoimmune reaction mediated by autoantibodies that are specific to keratin cells. Pemphigus vulgaris affects skin, mucous membranes of the nose, and perianal tissues. Erosions can range from quite small to large and life-threatening with a mortality rate of 5-15%. (1)
Case presentation of pemphigus vulgaris of the foot
I saw a unique case presentation this week of pemphigus vulgaris in the foot. The patient’s history was negative for new drugs, use of new socks or detergents. She described a painful, deep blister that presented within 24 hours. I monitored the blister over the course of two weeks while it spontaneously resolved without treatment.
Treatment of pemphigus vulgaris
In cases that do require treatment, corticosteroids or other immune suppressants at required to control the progress of the blistering and skin erosion.
(1) Ahmed AR, Moy R. Death in Pemphigus. J AmAcad Dermatol. 1982 Aug. 7(2)6221-8.