Final answer:
The term 'necrosis' used by a physician regarding a lesion suggests cell or tissue death, often due to severe infections like necrotizing fasciitis or impaired blood supply causing ischemia.
Step-by-step explanation:
When a physician uses the term necrosis referring to a lesion, it indicates that the area is affected by the death of cells or tissues. Necrosis can be a result of various conditions such as infections, like necrotizing fasciitis, or due to ischemia, where there is a lack of blood supply leading to tissue death. In the case studies provided, necrosis has led to severe health issues requiring medical intervention, such as the patient with necrotic toes caused by septicemic plague and the patient who needs skin-grafting surgery after surviving necrotizing fasciitis. Both patients experienced necrosis that affected their extremities and overall health.