What type of lesion is defined as swelling of serum?

A vesicle is characterized as a small, fluid-filled blister or lesion that forms due to the swelling of serum. This fluid can accumulate beneath the epidermis, creating a raised area that may vary in size. Vesicles are commonly associated with conditions such as infections, allergic reactions, or skin irritations. They typically contain clear fluid, which distinguishes them from other types of lesions.

Understanding this definition helps clarify why vesicles are significant in medical and clinical contexts, particularly in dermatology and pathology. In contrast to pustules, which contain pus, vesicles are specifically identified by their serum-like fluid. This distinction provides clarity in recognizing and diagnosing different skin conditions. Granulomas and ulcers represent other forms of lesions that do not involve the accumulation of serum in the same manner as vesicles do, making the understanding of each type essential for accurate identification and treatment approaches.