Fatal septicemia in 2 South American camelids with caudal C3-pyloric-duodenal adenocarcinoma

Abstract

Gastrointestinal adenocarcinomas are often reported in South American camelids (SAC). We describe here cases of gastroduodenal adenocarcinoma in an adult alpaca (Vicugna pacos) and a llama (Llama glama); both SACs were anorectic and lethargic before death. At autopsy, a prominent and firm caudal C3-pyloric-duodenal junction with stricture and ulceration was present in both animals, as were hemorrhages in various organs and hydrothorax. Microscopically, scattered nests, cords, and tortuous acini of neoplastic epithelial cells were embedded in desmoplastic stroma and invaded the submucosa and muscle layers of the gastroduodenal junction. The mucosa was necrotic, with gram-negative rods in the alpaca and colonies of gram-positive cocci in the llama. No tumor metastases were observed. The neoplastic cells immunolabeled for pancytokeratin. Escherichia coli was isolated from the alpaca and Streptococcus lutetiensis from the llama; septicemia was the cause of death in both animals. Although adenocarcinomas arising from gastric compartments and intestinal segments have been reported in SACs, adenocarcinoma of the caudal C3-pyloric-duodenal junction has not been reported previously in these species, to our knowledge.

Keywords: adenocarcinoma; alpacas; camelids; duodenum; llamas; stomach.

Figure 1.

Gross image of a gastroduodenal adenocarcinoma in a llama, case 2. A thickened pyloric-cranial duodenal junction infiltrated by an adenocarcinoma (asterisk) with coalescing ulcers, multifocal reddening, and stricture located between the third compartment (C3) of the stomach (upper organ) and the cranial duodenum (lower organ).

Figure 2.

Histology of the pyloric-cranial duodenal adenocarcinoma in an alpaca, case 1. A. Neoplastic gastric glands focally disrupt the muscularis mucosae (yellow asterisk) and invade the submucosa forming tortuous and proliferating acini (black asterisk). More neoplastic gastric glands (arrow) and numerous individual neoplastic epithelial cells are embedded in a collagenous matrix. H&E. B. Neoplastic cells form tortuous acini (arrows) and cords (asterisk) embedded in desmoplastic connective tissue in the muscle layer of the pyloric-duodenal junction. H&E. C. Irregular neoplastic acini within the submucosa have positive cytoplasmic immunolabeling for pancytokeratin (arrow). Note the cytoplasmic immunostaining of the gastric mucosal glands (asterisk). Pancytokeratin immunolabeling. Inset: mucus in some neoplastic cells. PAS stain.