Thymus - Hemorrhage
comment:Hemorrhage is characterized by the presence of extravasated erythrocytes within the thymic parenchyma ( Figure 1 , arrows). Hemorrhage can be seen in the cortex and/or medulla of the thymus of rodents and may be an agonal change. In the absence of necrosis or other lesions such as erythrophagocytosis ( Figure 2 , arrows) or pigment-laden macrophages, hemorrhage in the thymus may be attributed to necropsy technique (iatrogenic) and considered a dissection-induced artifact and not the result of a vascular lesion. However, thymic hemorrhage can occur with some vitamin deficiencies, so diet should be a consideration. Hemorrhage should be distinguished from congestion, where the blood is contained with well-defined vascular spaces lined by endothelial cells.
recommendation:Hemorrhage in the thymus that is not attributed to necropsy technique should be diagnosed and graded. Hemorrhage that is considered to be secondary to necrosis, inflammation, or neoplasia should not be diagnosed separately unless warranted by severity, but should be described in the pathology narrative.
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