Vesicle

A vesicle (from Latin vesicula – vesicle) is a primary cavity morphologic element up to 0.5 cm in size, rising above the skin level and filled with fluid. The fluid (exudate) may be serous (transparent), turbid or with an admixture of blood.

The wall of the vesicle is called the “coat” and the inner cavity is called the chamber.

Etiology and pathophysiology

Vesicles form as a result of delamination of the epidermis or detachment of the epidermis from the dermis. The most common causes are:

• Viral infections: Herpes simplex, chickenpox, shingles.
• Allergic reactions: Acute eczema, allergic dermatitis.

Clinical significance

When vesicles open (spontaneously or by scratching), wet erosions are formed, which are then covered with crusts. The presence of grouped vesicles on an erythematous (reddened) background is a classic sign of herpetic infection.