Equine carcinomatosis was noted in a 23-year-old Quarter Horse gelding that presented for autopsy. A ruptured urinary bladder was suspected based on clinical signs. On gross examination, there was a copious volume of clear, red, serosanguinous abdominal fluid. Variably sized irregular nodules were located along the body wall, diaphragm and visceral surfaces throughout the abdomen (Figure 1). The pancreas was completely obscured by similar nodules. Microscopically, the nodules corresponded to neoplastic foci of epithelial cells with nuclear polarity and abundant eosinophilic granules consistent with zymogen granules (Figure 2). Pancreatic acinar cell carcinoma was diagnosed based on these features. Carcinoma metastases along the surfaces of and invading multiple abdominal organs (also known as carcinomatosis) is seen in other veterinary species, such as chickens with ovarian carcinoma and nonhuman primates with intestinal adenocarcinoma. Pancreatic cancer has been sporadically diagnosed in horses. Interestingly, no cases of pancreatic carcinomatosis have yet to be reported in the literature.
This case report and others are also available in the Spring 2019 newsletter.
Heidi Pecoraro, DVM, PhD, Diplomate, DACVP