出血Hemorrhage · 脾脏 · 免疫系统 · NTP ntp-0030

Comment：
Hemorrhage is characterized by the presence of extravasated erythrocytes within the splenic capsule ( Figure 1 , arrow) or parenchyma ( Figure 2 , arrow). Hemorrhage can be focal to diffuse and may occur in a variety of conditions (e.g., splenic infarction), following chemical exposure, secondary to irradiation or traumatic injury, and in association with malignant neoplasms, especially hemangiosarcoma. A splenic hematoma is a localized collection of blood outside of blood vessels and is considered a subset of hemorrhage ( Figure 1 , arrow). Hemorrhage in the spleen should be distinguished from angiectasis, congestion, hemangioma, and hemangiosarcoma. Angiectasis is usually a focal lesion in the spleen and may be associated with an area of fibrosis. Its variably sized blood-filled spaces are lined by endothelium. Congestion can be difficult to differentiate from hemorrhage. Congestion is typically confined to the red pulp sinuses and may or may not have an identifiable cause. Hemangiomas and hemangiosarcomas are neoplasms of the splenic vascular endothelium.

Recommendation：
Whenever present in the spleen, hemorrhage should be diagnosed and graded. Splenic hematomas should not be diagnosed separately but diagnosed as hemorrhage. Hemorrhage need not be diagnosed if secondary to splenic neoplasia but should be noted in the pathology narrative.