A brief historical note may help clarify the meaning of lesion in SNOMED. Much of the early SNOMED CT content released in 2002 incorporated terminology from ICD-9, where lesion functioned as a nonspecific descriptor for any structural abnormality of a body part. ICD-10 continued this usage, applying lesion to denote an abnormal area of tissue identified by any method, without implying a specific morphology or cause. ICD-11 retains the same general meaning and uses lesion to indicate a localized structural abnormality seen on imaging, endoscopy, physical examination, or pathology, again without commitment to an underlying diagnosis.
SNOMED CT inherited this broad, non-etiological notion of lesion, and it continues to represent a generalized morphologic abnormality rather than a causal statement. For this reason, lesion is not equivalent to injury or traumatic injury. Injury inherently implies tissue damage, which may be traumatic (caused by an external force) or non-traumatic (arising spontaneously or through internal pathological processes). Traumatic injury, in contrast, explicitly requires an external physical cause. Thus, the three terms—lesion, injury, and traumatic injury—represent distinct semantic categories.
Clinical usage reflects these distinctions. A radiographic “lung lesion” simply denotes a structural abnormality on imaging, without implying etiology. A tendon rupture may be traumatic if produced by external force or non-traumatic if spontaneous or degenerative. In general, lesion should be understood as a broad descriptor for a structural abnormality of a body structure, independent of cause.