Spontaneous neoplasms in captive Virginia opossums (Didelphis virginiana): a retrospective case series (1989–2014) and review of the literature

Abstract

This retrospective project summarizes the types of neoplasms identified in Virginia opossums ( Didelphis virginiana) presented to the University of Tennessee, College of Veterinary Medicine (UTCVM) postmortem service in 1989–2014 and serves as a review of the literature. Of the 85 Virginia opossums identified from the UTCVM case database, there were 17 diagnoses of neoplasia from 12 cases (14%). These cases included 8 females, 2 males, and 2 neutered males. All opossums with known ages (11 of 12) were >2 y old. Pulmonary tumors, specifically minimally invasive or lepidic-predominant adenocarcinomas, were the most common diagnosis and accounted for 53% (9 of 17) of the neoplasms. Additional tumors included acute myeloid leukemia with eosinophil maturation, hepatic hemangiosarcoma, sarcoma (unknown origin), squamous cell carcinoma, disseminated mast cell tumor, trichoblastoma, thyroid adenoma, and an osteoma. These findings serve as a reference for the types of spontaneous neoplasms in Virginia opossums; based on these findings, neoplasia should be considered as a differential in mature captive Virginia opossums.

Fibroblastic osteosarcoma in a white-eared opossum (Didelphis albiventris)

“…Current searches within scientific database platforms showed no evidence of bone neoplasm descriptions in Didelphis albiventris. Pope & Donnell (2017) observed 17 neoplasm cases in Didelphis virginiana, 14 of those categorized as malignant and 3 benign. In the same study, the neoplasm was identified as the reason for the death and euthanasia of 6 animals.…”

“…These animals are affected by infectious and neoplastic disorders (Baker et al 1995). There is limited up-to-date scientific literature about neoplasm in opossums, being restricted to cases in the Didelphis virginiana species (Pope & Donnell 2017). There is also a scarcity of information about the incidence, prevalence, predisponent factors, and behavior of neoplasms in wild animals (Johnson et al 2014, Madsen et al 2017.…”

Systemic mastocytosis and probable mast cell leukaemia in a koala (Phascolarctos cinereus)

“…Only three reports of mast cell neoplasia in marsupials could be located; a case of dermal mastocytoma with splenic metastasis in a kowari ( Dasyuroides byrnei ), mastocytoma in an Eastern barred bandicoot ( Parameles gunnii ) and systemic mastocytosis in a Virginia opossum ( Didelphis virginiana ) . In humans, systemic mastocytosis and mast cell leukaemia (MCL) are uncommon diseases.…”

“…23 Only three reports of mast cell neoplasia in marsupials could be located; a case of dermal mastocytoma with splenic metastasis in a kowari (Dasyuroides byrnei), 24 mastocytoma in an Eastern barred bandicoot (Parameles gunnii) 20 and systemic mastocytosis in a Virginia opossum (Didelphis virginiana). 25 In humans, systemic mastocytosis and mast cell leukaemia (MCL) are uncommon diseases. The primary diagnostic criterion of MCL in humans is mast cells composing at least 20% of all nucleated cells in bone marrow smears with cytology smears, the gold standard for defining the percentage of mast cells, being preferred over biopsies for histology.…”

Metastasis in the wild: investigating metastasis in non-laboratory animals

“…In both species, the GISTs arise due to oncogenic mutations in the KIT tyrosine kinase, which also drives canine cutaneous mast cell tumours [111]. There are also case reports of a mast cell tumour in a llama, which exhibited positive membrane KIT expression [112], and a captive opossum ( Didelphis virginiana ), in which c-KIT positive cancerous cells were found to have spread to distant sites, including the liver, skin, kidney, pancreas and spleen [43].…”