Spontaneous neoplasms in captive red-bellied lemurs (Eulemur rubriventer).

Red-bellied lemurs (Eulemur rubriventer: genus Eulemur, family Lemuridae, Suborder Strepsirrhini) are non-human primates endemic to the forests of Madagascar and listed as 'vulnerable' on the IUCN Red List of Threatened Species. Currently, descriptions of neoplasia in this species are extremely scarce, with only one case of hepatocellular adenoma reported. Prosimian submissions received by the Anatomic Pathology Service at North Carolina State University from January 2010 to January 2021 were retrieved. A total of 200 cases of Strepsirrhini prosimians were identified, representing 57 (28.5%) individuals from the genus Eulemur of which seven (12.3%) cases were red-bellied lemurs. Neoplasia was identified in two of the seven (28.57%) cases. The first case was a 25-year-old, intact female with hepatocellular carcinoma and the second a 33-year-old, intact female with a cervical mass consistent with osteoblastic osteosarcoma arising from the left clavicular bone. Hepatocellular neoplasms are commonly reported in prosimians, with carcinomas more frequent than adenomas. In contrast, osteosarcoma has been rarely described in lemuriformes, with four cases reported. To our knowledge, this is the first report of osteosarcoma and hepatocellular carcinoma in a red-bellied lemur.

Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Metastatic Digital Chondrogenic Melanocytic Tumour in a Dog.

A 9-year-old intact male Brazilian Mastiff dog with a 1-year history of progressive severe swelling in all four limbs and significant locomotory difficulty was euthanized due to unresponsiveness to medical management. Macroscopically, the distal phalanx of the 5th digit of the left hindlimb was replaced by a cutaneous, non-ulcerated, 3.0 cm diameter, multilobulated, black, firm nodule. The cortical bones of the appendicular skeleton were thickened and partially effaced by infiltrative coalescing nodules (0.1-1.0 cm diameter). The lungs, heart, pleura, mesentery, adrenal glands and kidneys were infiltrated by similar nodules (0.5-3.5 cm diameter). Histological evaluation of the masses revealed a non-encapsulated malignant neoplasm composed of spindloid to polygonal cells that contained variable amounts of intracytoplasmic melanin and were arranged in haphazardly interlacing streams and bundles supported by scant fibrovascular stroma with myxoid and chondroid matrix formation. Neoplastic cells had intense cytoplasmic labeling for S100 and 10% had moderate cytoplasmic immunoreactivity for Melan-A. To the authors' knowledge, this is the first description of a canine metastatic digital chondrogenic melanocytic tumour with strongly suggestive chondroid differentiation of neoplastic melanocytes.

Concurrent Clostridial Enteritis and Oviductal Adenocarcinoma with Carcinomatosis in an Adult Alpaca (Vicugna pacos).

An adult alpaca (Vicugna pacos) with a history of colic and anorexia was euthanized because of failure to respond to treatment. Macroscopically, pale-tan, multifocal to coalescing, firm nodules and plaques markedly expanded the omentum, mesentery and the parietal and visceral peritoneum of multiple abdominal organs, especially the right oviduct and associated mesosalpinx. Abundant dark-red watery digesta were present in the duodenum and jejunum. Histological evaluation of the right oviduct, abdominal visceral nodules and plaques and mesenteric lymph nodes revealed transmural expansion and replacement by an epithelial malignant neoplasm, comprised of tubules and acini of ciliated columnar cells supported by abundant fibrous connective tissue. Both ovaries were histologically normal. On the basis of the ciliated morphology of the neoplastic cells, the focus on the proximal reproductive tract and the unremarkable ovaries, a reproductive tubal adenocarcinoma with carcinomatosis was diagnosed, with both the endometrium and oviduct considered as the tissues of origin. The prominent ciliated morphology of the neoplastic cells and the classification of human fallopian tube (oviduct) neoplasia lead us to propose oviductal adenocarcinoma with widespread carcinomatosis as the definitive diagnosis. The lamina propria of the small intestine was infiltrated segmentally by lymphocytes, plasma cells and neutrophils, and Clostridium perfringens with beta2 toxin production was identified by polymerase chain reaction in the small intestinal contents. To our knowledge, this is the first report of these two distinct diseases in an alpaca.