What defines a bulla in dermatological terms?

A bulla is defined as a blister that contains fluid, typically measuring more than 0.5 centimeters in diameter. This fluid is usually clear but can also contain blood or pus, depending on the underlying cause. Bullae form when there is a separation between the epidermis and dermis layers of the skin, allowing fluid to accumulate in the space created.

In dermatology, distinguishing between a bulla and other skin lesions is important for diagnosis and treatment. Small discolored patches on the skin are referred to as macules or patches rather than bullae. Deep tissue infections, on the other hand, may lead to the development of different kinds of skin lesions but are not classified as bullae. A type of skin cancer would present quite differently and is categorized under neoplasms, not as a bulla. Understanding these definitions is crucial for proper assessment and intervention in dermatological conditions.