Alimentary System

Esophagus, Muscularis - Degeneration

Narrative
Comment:
Degeneration is characterized by decreased fiber size (Figure 1 and Figure 2), hypercontraction, "twisting and curling of fibers," homogeneous eosinophilic to granular or floccular cytoplasm, loss of striations, and mineralization. Macrophages (Figure 3 and Figure 4) are frequently found in areas of muscle degeneration and necrosis. Gavage trauma can result in damage to the muscular wall of the esophagus, resulting in muscle degeneration and necrosis or perforation.
Recommendations:
Whenever present, degeneration of the tunica muscularis should be diagnosed as "esophagus, muscularis - degeneration" and graded based upon the extent of the lesion. It should be noted in the narrative whether the pathologist considers this lesion to be due to chemical exposure or a gavage error.
References:

Brown HR, Hardisty JF. 1990. Oral cavity, esophagus and stomach. In: Pathology of the Fischer Rat (Boorman GA, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, CA, 9-30.

Abstract: https://www.ncbi.nlm.nih.gov/nlmcatalog/9002563

Valentine BA, McGavin MD. 2007. Skeletal muscle. In: Pathologic Basis of Veterinary Disease, 4th ed (McGavin MD, Zachary JF, eds). Mosby, St Louis, MO, 973-1039.

  • Image of degeneration in the esophagus muscularis from a male F344/N rat in a chronic study

    Esophagus, Muscularis - Degeneration in a male F344/N rat from a chronic study. Decreased muscle fiber size (arrow).

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<p>Esophagus, Muscularis - Degeneration in a male F344/N rat from a chronic study. Decreased muscle fiber size (arrow).</p>

Esophagus, Muscularis - Degeneration in a male F344/N rat from a chronic study. Decreased muscle fiber size (arrow).
<p>Esophagus, Muscularis - Degeneration in a male F344/N rat from a chronic study (higher magnification of Figure 1). Note the decreased muscle fiber size (arrow).</p>

Esophagus, Muscularis - Degeneration in a male F344/N rat from a chronic study (higher magnification of Figure 1). Note the decreased muscle fiber size (arrow).
<p>Esophagus, Muscularis - Degeneration in a female Sprague-Dawley rat from a chronic study. There are infiltrates of macrophages amid the muscle fibers (arrow).</p>

Esophagus, Muscularis - Degeneration in a female Sprague-Dawley rat from a chronic study. There are infiltrates of macrophages amid the muscle fibers (arrow).
<p>Esophagus, Muscularis - Degeneration in a male F344/N rat from a chronic study (higher magnification of Figure 3). There are infiltrates of macrophages amid the muscle fibers (arrow).</p>

Esophagus, Muscularis - Degeneration in a male F344/N rat from a chronic study (higher magnification of Figure 3). There are infiltrates of macrophages amid the muscle fibers (arrow).

Authors:

Linda H. Kooistra, DVM, PhD, DACVP
Pathologist
Charles River Laboratories, Inc.
Research Triangle Park, NC

Abraham Nyska, DVM, Diplomate ECVP, Fellow IATP
Expert in Toxicologic Pathology
Visiting Full Professor of Pathology
Sackler School of Medicine, Tel Aviv University Timrat Israel

Reviewers:

Joel R. Leininger, DVM, PhD
Senior Pathologist
MedImmune
Washington, DC

Amy Brix, DVM, PhD, DACVP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC