Esophagus, Muscularis - Degeneration

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).
Figure 1 of 4
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 (higher magnification of Figure 1). Note the decreased muscle fiber size (arrow).
Figure 2 of 4
Image of degeneration in the esophagus muscularis from a female Sprague-Dawley rat in a chronic study
Esophagus, Muscularis - Degeneration in a female Sprague-Dawley rat from a chronic study. There are infiltrates of macrophages amid the muscle fibers (arrow).
Figure 3 of 4
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 (higher magnification of Figure 3). There are infiltrates of macrophages amid the muscle fibers (arrow).
Figure 4 of 4
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comment:

Degeneration is characterized by decreased fiber size ( Figure 1image opens in a pop-up window and Figure 2image opens in a pop-up window ), hypercontraction, "twisting and curling of fibers," homogeneous eosinophilic to granular or floccular cytoplasm, loss of striations, and mineralization. Macrophages ( Figure 3image opens in a pop-up window and Figure 4image opens in a pop-up window ) 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.

recommendation:

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: http://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.