Thymus - Necrosis, Lymphocyte

Thymus - Necrosis, Lymphocyte in a male Harlan Sprague-Dawley rat from a subchronic study. Treatment with dexamethasone resulted in severe lymphocyte apoptosis with focal areas of necrosis.
Figure 1 of 2
comment:
Necrosis of thymic lymphocytes can occur in rats and/or mice as a direct effect of toxicants such as corticosteroids, estrogen, and cyclophosphamide, and usually in conjunction with severe lymphocyte apoptosis. The cortical and/or medullary lymphocytes may be involved ( Figure 1


recommendation:
Whenever there is necrosis of thymic lymphocytes, but other components of the thymus are spared, "Thymus - Necrosis, Lymphocyte" should be diagnosed and assigned a severity grade. A diagnosis of "Thymus - Necrosis" should be made when all cellular components of the thymus are necrotic. Necrosis-associated inflammation, hemorrhage, or mineralization should not be diagnosed separately unless warranted by severity, but should be included in the pathology narrative. Lymphocyte necrosis must be differentiated from lymphocyte apoptosis. If lymphocyte necrosis and apoptosis occur concurrently, diagnose and grade both lesions.references:
Elmore SA. 2006. Enhanced histopathology of the thymus. Toxicol Pathol 34:656-665. Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1800589/
Pearse G. 2006. Histopathology of the thymus. Toxicol Pathol 34:515-547. Full Text: http://tpx.sagepub.com/content/34/5/515.long
Stefanski SA, Elwell MR, Stromberg PC. 1990. Spleen, lymph nodes, and thymus. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, 369-394.
Ward JM, Mann PC, Morishima H, Frith CH. 1999. Thymus, spleen, and lymph nodes. In: Pathology of the Mouse (Maronpot RR, ed). Cache River Press, Vienna, IL, 333-360.
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