Bulla

A bulla (from Latin bulla) is a large (more than 0.5-1 cm in diameter) primary cavity filled with fluid. It is essentially a “large vesicle”. Bullae may be located intraepidermally (in the epidermis) or subepidermally (under the epidermis).

The “cover” of the bladder may be tense or flabby.

Etiology and pathophysiology

The causes of blister formation are often associated with serious pathologic processes:

• Mechanical factors: Friction (calluses).
• Thermal factors: Second-degree burns.
• Autoimmune diseases: Vesicular vesicles (acantholysis – loss of connection between epidermal cells), bullous pemphigoid.
• Toxic-allergic reactions: Lyell’s syndrome.

Clinical significance

The presence of blisters often indicates the severity of the skin lesion. When the blister ruptures, a large erosive surface is formed, which is a gateway for infection and results in significant loss of body fluid and protein.