Abnormal blistering of the skin

What it means

The presence of one or more bullae on the skin, defined as fluid-filled blisters more than 5 mm in diameter with thin walls.

A bulla is a large vesicle described as a rounded or irregularly shaped blister containing serous or seropurulent fluid, equal to or greater than 10mm. In approaching blistering diseases, there are 3 fundamental criteria to consider: (1) the site or level of the blister (or the lowest level of vesiculation): subcorneal, midepidermis, suprabasal, subepidermal; (2) the findings that implicate the mechanism of blister formation (spongiosis, acantholysis, blistering degeneration, or epidermolysis); and (3) the type of inflammation (neutrophilic, lymphocytic, eosinophilic, mixed), if present.

In everyday care

Most people with this sign do not have a rare disease — it appears in common conditions far more often. These general reference pages cover the same topic:

Rare diseases that can present with this103

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions, and Orphanet separately records 1 disease where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Blister · Blistering, generalised · Blisters · Skin blisters · Skin bullae