Abstract
Image 1
B. Grass awn cheilitis
Grass awns from plants in the genus Setaria (foxtails) and genus Andropogon (broomsedge) can cause oral ulcers in herbivores. Plants that produce sharp awns are not generally grazed heavily when other forage is readily available, but may cause severe ulceration of the lips (Image 1a) and/or tongue, especially in animals with little other accessible forage. These ulcers may grossly resemble autoimmune lesions, viral diseases such as vesicular stomatitis, or chemical irritant exposure. Histologically, the plant material is surrounded by mixed inflammation and can be distinguished from free hair shafts by the presence of rectangular cell walls (Image 1b).
Additional reading: Graves MT, Ivey, JL. Ulcerative stomatitis associated with ingestion of broomsedge hay in a horse. Vet Rec Case Rep. 2018;
Contributor: Abby English, University of Georgia
Image 2
A. Gelatin foam
Gelatin foam is a biodegradable hemostatic agent used during surgical procedures. It comes in many forms, including sponges, sheets, and powders. Like fibrin, gelatin foam adheres directly to the source of hemorrhage and packs it to assist clot formation. In addition, its porous nature allows it to serve as a meshwork for cell adhesion. It completely degrades after 4 to 6 weeks. Histologically, gelatin foam is recognized as basophilic acellular angled deposits (Image 2) surrounded by erythrocytes and inflammatory cells. Electrocautery causes nuclear streaming and coagulation. Starch granules are hexagonal with central dark spots. Monsel’s solution causes basophilia, partial desquamation, and epithelial cracking.
Additional Reading: Hu J, Albadawi H, Chong BW, et al. Advances in biomaterials and technologies for vascular embolization. Adv Mater. 2019;
Contributor: C. Robert Stilz, University of Tennessee
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B. Gossypiboma
The refractile strands are characteristic of cotton; a mass composed of cotton is called a gossypiboma. In this case, the gossypiboma was surrounded by a sarcoma (Image 3). The pathogenesis for fibrosarcoma arising secondary to a foreign body is unknown but is believed to be related to that of feline injection site sarcoma, in which chronic inflammation and wound healing cause the proliferation and neoplastic transformation of fibroblasts. Vaccine adjuvant is amorphous and is often phagocytosed. Refractile oxalate crystals formed by Aspergillus take various shapes and are associated with fungal elements. In cholesterol granulomas, the cholesterol crystals leave acicular clefts.
Additional Reading: Haddad J, Goldschmidt MH, Patel RT. Fibrosarcoma arising at the site of a retained surgical sponge in a cat. Vet Clin Pathol. 2010;
Contributor: Alec Daniels, University of Tennessee
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C. Foreign body embolism
This rabbit developed respiratory signs and died following a surgical procedure. Microscopically, foreign material was identified in the lumen of pulmonary arteries with variable vasculitis. The foreign material is consistent with embolized hydrophilic polymer, used to coat medical devices, including intravenous catheters. On occasion, the polymer can delaminate within the vasculature (usually found in the brain and lungs in people), where it can cause downstream vasculitis, infarction, and rarely death. The appearance varies with material type. In this case, the material was periodic acid-Schiff-positive (Image 4a) and unstained by Masson trichrome (Image 4b).
Additional Reading: Mehta RI, Mehta RI. Hydrophilic polymer embolism: an update for physicians. Am J Med. 2017;
Contributor: Laura Bassel, Center of Advanced Preclinical Research, National Cancer Institute
Veterinary Pathology invites submission of exceptional gross or microscopic images for consideration as an Image Challenge, along with a multiple-choice question and answer. For details, see the Instructions to Authors on the journal website.