坏死Necrosis · 骨 · 骨骼肌肉系统 · NTP ntp-0572

Comment：
Necrosis of bone ( Figure 1 , Figure 2 , Figure 3 , Figure 4 , and Figure 5 ) can be characterized by disruption of normal architecture and fragmentation of bony trabeculae in the medullary cavity, loss of osteoblasts from bone surfaces, or loss of osteocytes from lacunae. There is often marrow necrosis and hemorrhage. Focal necrosis may be isolated in sequestra or replaced by fibrous connective tissue. Necrosis may result from a variety of etiologies, including vascular compromise, inflammation, trauma, or neoplasia. Idiopathic necrosis of bone occasionally occurs in mice, particularly at the epiphysis or metaphysis of the distal femur and proximal tibia; vascular compromise has been suspected in some of these cases.

Recommendation：
Necrosis of the bone should be diagnosed and given a severity grade. If the cause of the necrosis can be discerned, it should be discussed in the narrative. When necrosis occurs as a secondary component of another process, it should not be diagnosed but should be described in the narrative. Lesions that are secondary to necrosis, such as inflammation or hemorrhage, should not be diagnosed separately unless warranted by severity but should be noted in the pathology narrative.