Spleen - Pigment

comment:
The presence of a small amount of intracytoplasmic pigment within the splenic red pulp macrophages is a common background finding in rodents. Pigment can be hemosiderin, ceroid/lipofuscin, melanin, or test article related. It is typically found in the red pulp ( Figure 1

recommendation:
Pigment in the red and/or white pulp of the spleen should be diagnosed when increased or decreased due to treatment and assigned a severity grade. A diagnostic modifier (i.e., "increased" or "decreased") should be included in the diagnosis to indicate whether the pigment is increased or decreased relative to concurrent controls. Definitive pigment identification is often difficult in histological sections, even with a battery of special stains. Therefore, a diagnosis of "pigment" (as opposed to diagnosing the type of pigment, e.g., hemosiderin or lipofuscin) is most appropriate. Morphological features of the pigment should be described in the pathology narrative. If the presence of pigment is secondary to age or not toxicologically meaningful, the pigment should not be diagnosed. The pathologist should use his or her judgment in deciding whether secondary deposits of pigment are prominent enough to warrant a separate diagnosis.references:
National Toxicology Program. 2010. NTP TR-558. Toxicology and Carcinogenesis Studies of 3,3′,4,4′-Tetrachloroazobenzene (TCAB) [CAS No. 14047-09-7] in Harlan Sprague-Dawley Rats and B6C3F1 Mice (Gavage Studies). NTP, Research Triangle Park, NC. Abstract: https://ntp.niehs.nih.gov/go/33564
National Toxicology Program. 2011. NTP TR-570. Toxicology and Carcinogenesis Studies of α,β-Thujone (CAS No. 76231-76-0) in F344/N Rats and B6C3F1 Mice (Gavage Studies). NTP, Research Triangle Park, NC. Abstract: https://ntp.niehs.nih.gov/go/36137
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.
Suttie AW. 2006. Histopathology of the spleen. Toxicol Pathol 34:466-503. Full Text: http://tpx.sagepub.com/content/34/5/466.full.pdf
Ward JM, Rehg JE, Morse HC III. 2012. Differentiation of rodent immune and hematopoietic system reactive lesions from neoplasias. Toxicol Pathol 40:425-434. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/22215512
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.
Web page last updated on: January 27, 2015