Lesion
A lesion is any abnormality in the tissue of an organism (in layman's terms, “damage”), usually caused by disease or trauma. Lesion is derived from the Latin word laesio meaning injury.
Classification
Lesions can be classified based on various criteria, including their cause, appearance, location, and characteristics. Here are some common ways to classify lesions:
By Cause
Infectious Lesions: Caused by pathogens such as bacteria, viruses, fungi, or parasites. Examples include cold sores (caused by herpes simplex virus), bacterial skin infections, and fungal nail infections. Inflammatory Lesions: Result from the body's immune response to injury, infection, or irritation. Examples include acne, eczema, and psoriasis. Neoplastic Lesions: Comprise tumors, which can be either benign (non-cancerous) or malignant (cancerous). Tumors may arise from various tissues and organs. Traumatic Lesions: Result from physical injury or trauma, such as bruises, contusions, and lacerations. By Appearance:
Macules: Small, flat, discolored spots on the skin, often less than 1 cm in diameter. Examples include freckles and flat moles. Papules: Small, raised, solid bumps on the skin, usually less than 1 cm in diameter. Examples include acne pimples. Nodules: Larger, deeper papules that extend into the dermis or subcutaneous tissue. Plaques: Larger, flat-topped, raised areas on the skin, often associated with conditions like psoriasis. Vesicles: Small, fluid-filled blisters, less than 1 cm in diameter. Examples include chickenpox blisters. Pustules: Pimples containing pus. Ulcers: Open sores with loss of tissue. By Location:
Cutaneous Lesions: Located on the skin. Mucosal Lesions: Found on mucous membranes, such as in the mouth, gastrointestinal tract, or genital area. Systemic Lesions: Affect internal organs and may not be visible on the skin or mucous membranes. By Characteristics:
Benign Lesions: Non-cancerous and typically do not invade nearby tissues. Examples include benign moles and warts. Malignant Lesions: Cancerous and have the potential to spread to other parts of the body. Examples include malignant melanoma and lung cancer. By Specific Classification:
Some lesions have unique classifications based on their characteristics, such as angiomas (lesions related to blood vessels), lipomas (benign fatty tumors), or actinic keratoses (premalignant skin lesions caused by sun exposure). Classifying lesions is an essential step in medical diagnosis and treatment planning. Healthcare professionals use these classifications to determine the underlying cause, prognosis, and appropriate treatment options for patients with lesions.
see Mass lesion
see Brain lesion
see Brainstem lesion.