What is a bulla?

A bulla is defined as a fluid-filled lesion that is larger than 1 cm in diameter. Bullae are distinct from smaller vesicles, which are also fluid-filled but are less than 1 cm. This definition is crucial in dermatological contexts, as it helps in identifying various skin conditions and their progression. Bullae can occur due to various dermatological issues, including burns, infections, or autoimmune disorders, and their size often indicates the severity or nature of the underlying condition.

The other options describe different types of skin lesions or conditions: an elevated solid mass refers more to nodules or tumors, a superficial elevated lesion filled with purulent fluid can represent pustules (not bullae), and thinning of the skin that appears white or translucent describes atrophy. Understanding these terms aids in accurately diagnosing skin-related issues.