Primary intracranial fibrosarcoma in a southern sea otter Enhydra lutris nereis

Southern sea otters Enhydra lutris nereis, a threatened marine mammal species, face numerous environmental and infectious disease challenges in their native habitat of coastal California, USA. However, there are few published cases describing neoplasia in sea otters despite their relatively long lif...

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Bibliographic Details
Published in:Diseases of aquatic organisms 2020-03, Vol.138, p.207-213
Main Authors: Armwood, Abigail R, Anderson, Chelsea E, Clauss, Tonya, Camus, Alvin C
Format: Article
Language:English
Subjects:
Actin
Animals
Antigens
Aquatic mammals
California
Coagulation factors
Coastal ecology
Cytokeratin
Desmin
E-cadherin
Endangered Species
Enhydra lutris
Enhydra lutris nereis
Euthanasia
Fibrosarcoma
Fibrosarcoma - veterinary
Glial fibrillary acidic protein
Immunoreactivity
Infectious diseases
Life span
Magnetic resonance imaging
Male
Marine mammals
Meninges
Muscles
Neoplasia
Neuroimaging
Otters
Pleomorphism
Seizures
Smooth muscle
Substantia alba
Substantia grisea
Threatened species
Vascularization
Vimentin
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Summary:Southern sea otters Enhydra lutris nereis, a threatened marine mammal species, face numerous environmental and infectious disease challenges in their native habitat of coastal California, USA. However, there are few published cases describing neoplasia in sea otters despite their relatively long life span when cared for in aquarium settings. An 18 yr old neutered male southern sea otter, born and raised in human care, presented with an acute onset of seizures and dull mentation. Magnetic resonance imaging of the head revealed a large, central brain lesion. After no improvement with treatment, euthanasia was elected due to a poor prognosis. Grossly, a poorly demarcated, granular, tan mass expanded the cranial meninges in the longitudinal fissure at the level of the cruciate sulcus and extended into the underlying gray matter and superficial white matter. Histologically, the mass was composed of spindle cells, forming haphazardly arranged interlacing bundles and herringbone patterns, with a high mitotic count, moderate cellular pleomorphism, and prominent vascularization. Neoplastic cells demonstrated positive immunoreactivity for vimentin and negative immunoreactivity for smooth muscle actin, factor VIII-related antigen, S100, melan-A, E-cadherin, desmin, glial fibrillary acidic protein, and cytokeratin AE1/AE3. Based on gross, histologic, and immunohistochemical findings, the mass was most consistent with a primary intracranial fibrosarcoma (PIF). PIFs are a rare neoplasm in both humans and other animals with few reports in the veterinary literature. This is the first recorded case of a PIF in a sea otter.
ISSN:0177-5103
1616-1580
DOI:10.3354/dao03457