Final answer:
Secondary lesions in dermatology are alterations of primary skin lesions due to infection, trauma or other stages of diseases. These include changes like ulcers, scars, scales, crusts and fissures. Examples can be found in diseases like syphilis and conditions like acne, folliculitis, and skin cancer.
Step-by-step explanation:
Secondary lesions are changes that result from the evolution of primary lesions due to infection, scratching, trauma, or various stages of a disease. For instance, in dermatology, primary lesions such as papules, macules, or vesicles can evolve under certain conditions into secondary lesions such as ulcers, scales, crusts, scars or fissures.
A classic example is in the case of syphilis. The disease starts with a primary ulcerated sore (chancre). As the disease progresses to the secondary stage, it manifests as a rash, which is a secondary lesion, often beginning on the palms or soles of the feet.
Another example includes the scarring that results from damaged skin cells, often due to excessive exposure to UV radiation. The fibroblast cells repair the damaged skin, generating scar tissue in the form of collagen, which appears different from normal skin. Inflammation of hair follicles, as in the case of acne or folliculitis, may also result in secondary lesions if the primary comedones (whiteheads or blackheads) rupture or become infected.
Similarly, injury or damage to the skin can cause secondary lesions as the skin's physical barrier is broken, providing an entryway for microbes and potentially leading to localized or systemic infections.
Learn more about Secondary Lesions