Departamento de Patologia Veterintária, Universidade Estadual Paulista, Jaboticabal, SP, Brazil
Lymphoid tumors are among the most common types of the neoplasms of domestic animals.5,7 There are many different cytologic forms of lymphosarcoma. They are variable within and between species, giving rise to their classification as multicentric, thymic, alimentary, splenic and cutaneous lymphosarcoma.5 This report describes a cutaneous lymphosarcoma in a crab-eating raccoon (Procyon cancrivorus).
A 9-year-old, captive, female, crab-eating raccoon (Procyon cancrivorus) was housed with a male in an outside enclosure. The primary manifestation of disease was involvement of the skin. The animal showed a delineated and firm consistency mass, localized in the skin of the left side of the chest. The skin was reddish and thick, and the hair coat was thinner than normal. Dexamethasone was used without improvement. The mass was surgically removed, and representative tissue samples were fixed in 10% formalin solution for histopathology.
Results and Discussion
Histologically, the mass was composed of large and rounded neoplastic lymphocytes, with large nuclei and rare mitotic figures. There was moderate cellular pleomorphism, and the growth was expansive.
There are some significant differences between this case and the lymphosarcomas documented by other authors in North American raccoons.2,7 This case presented as just a mass. The other cases were diagnostic on postmortem examination. They found infiltration in various tissues including lymph nodes, spleen, liver, pancreas,2 kidney, brain, and meninges.7 We found large lymphoblastic cells. Some authors found large lymphoblastic cells,2 and some found well-differentiated, small neoplastic lymphocytes.7
Neoplasia, with the exception of thyroid tumors, appears to be rare in raccoons.2,4 In a retrospective survey of over 400 raccoon (Procyon lotor) necropsies, one author found only two cases of neoplasia, an astrocytoma of the brain and a fibroma of the skin.1 Other reports show eight cases of adrenal gland adenomas,4 two cases of multifocal skin papillomas,3 hepatocellular adenoma and adrenocortical adenoma.6
The paucity of reported cases of neoplasia in raccoons may be due to genetic resistance of the raccoon to neoplasia, high turnover in free-ranging populations, or a lack of thorough pathologic examination of sufficient numbers of raccoons.4
This report represents the first recorded lymphosarcoma in a crab-eating raccoon.
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