Immune System

Lymph Node - Atrophy

Narrative
Comment:
Lymph node atrophy may result from any toxic insult or disease that causes lymphocyte necrosis or apoptosis. Changes may include depletion of paracortical lymphocytes (Figure 1, arrow), a decrease in the number and size of follicles with few to no germinal centers (Figure 1, arrowhead), and a decrease in cellularity of medullary cords; depending on severity, the paracortical stromal cells and high endothelial venules may be more prominent (Figure 2, arrows). Progressive loss of lymphocytes may cause shrinking (atrophy) of a lymph node that is apparent grossly or subgrossly. Atrophic lymphoid tissue may be replaced by adipose tissue and possibly collagen. The severity of atrophy may also vary between lymph nodes within the same animal. Atrophy may result from toxic insult but may also be seen in aged rats and mice. Age-related changes should not be diagnosed.
Recommendations:
Lymph node atrophy should be diagnosed and graded unless it is determined to be age related. Plane of section and location should also be considered when evaluating the lymph nodes.
References:

Elmore SA. 2006. Enhanced histopathology of the lymph nodes. Toxicol Pathol 34:634-647.

Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1783683/

Elmore SA. 2006. Histopathology of the lymph nodes. Toxicol Pathol 34:425-454.

Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892634/

Frith CH, Ward JM, Chandra M, Losco PE. 2000. Non-proliferative lesions of the hematopoietic system in rats. In: Guides for Toxicologic Pathology.TP/ARP/AFIP, Washington, DC.

Full Text: https://www.toxpath.org/docs/SSNDC/HematopoieticNonprolifRat.pdf

National Toxicology Program. 2004. 13-Week Study (No. C20306) of PCN 66/67 (CAS No. PCNCOMPARISN) in F344 Rats and Sprague-Dawley Rats (Gavage Studies). NTP, Research Triangle Park, NC.

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.

  • Image of atrophy in the lymph node from a female F344/N rat in a subchronic study

    Lymph node - Atrophy in a female F344/N rat from a subchronic study. With early lymph node atrophy, paracortical lymphocytes are depleted (arrow), and number and size of follicles are decreased (arrowhead).

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Lymph node - Atrophy in a female F344/N rat from a subchronic study. With early lymph node atrophy, paracortical lymphocytes are depleted (arrow), and number and size of follicles are decreased (arrowhead).
Lymph node - Atrophy in a female F344/N rat from a subchronic study. With early lymph node atrophy, paracortical lymphocytes are depleted (arrow), and number and size of follicles are decreased (arrowhead).
Lymph node - Atrophy in a female F344/N rat from a subchronic study (higher magnification of Figure 1). High endothelial venules (arrows) may be more prominent with lymphocyte depletion.
Lymph node - Atrophy in a female F344/N rat from a subchronic study (higher magnification of Figure 1). High endothelial venules (arrows) may be more prominent with lymphocyte depletion.

Authors

Kristen Hobbie, DVM, PhD
Principal Pathologist
Huntingdon Life Sciences
Peterborough, UK

Susan A. Elmore, MS, DVM, DACVP, DABT, FIATP
Staff Scientist, NTP Pathologist
NTP Pathology Group
National Toxicology Program
National Institute of Environmental Health Sciences
Research Triangle Park, NC

Holly M. Kolenda-Roberts, DVM, PhD, DACVP
Veterinary Pathologist
SNBL USA
Everett, WA

Reviewers

Jerrold M. Ward, DVM, PhD, DACVP, FIATP
Veterinary Pathologist
Global VetPathology
Montgomery Village, MD

Robert R. Maronpot, DVM, MS, MPH, DACVP, DABT, FIATP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC