Lesion
A lesion is any localised area of altered skin. The word is deliberately neutral: it describes that something is there and where it is, without implying anything about what it is or how serious it might be.
Few words alarm patients more and mean less. A lesion is simply a defined area of skin that differs from the skin around it, and hearing the word in a consultation carries no information about seriousness.
Its neutrality is the point. Clinicians need a way to refer to something before they know what it is, and every alternative smuggles in an assumption. Describing an area as a lesion allows it to be examined, measured and discussed without prejudging anything.
More precise words attach once description begins. A macule is flat and differs only in colour. A papule is small and raised. A nodule is larger and deeper. A plaque is raised and broad relative to its height. A vesicle contains fluid; a pustule contains pus.
Further terms describe behaviour rather than shape. Benign and malignant refer to how something behaves, primary describes a lesion arising directly from a condition, and secondary describes one resulting from something else such as scratching or infection.
Where a lesion needs examining under a microscope, the tissue is obtained by biopsy or excision and reported by a pathologist. That is the point at which the neutral word is finally replaced by a specific one.
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