Ovarian teratoma in a bitch

Autor: Carlos Everton Curti, Eliane Thomaselli Fuck, Selwyn Arlington Headley, Egon José Fuck
Rok vydání: 2006
Předmět:
Zdroj: The Veterinary record. 158(16)
ISSN: 0042-4900
Popis: PRIMARY ovarian tumours are very rare in domestic animals (Sforna and others 2003); they may be of epithelial, germ cell, stromal sex cord or mesenchymal origin (Nielsen and Kennedy 1990, Kennedy and Miller 1993, Sforna and others 2003). Teratomas are rare tumours composed of structures derived from multiple embryonic germ cells (ectoderm, endoderm or mesoderm) that may occur within any organ (Nielsen and Kennedy 1990, Kennedy and Miller 1993). Most teratomas described in animals have been intragonadal (Basaraba and others 1998, Toyosawa and others 2000, Miyoshi and others 2001, Sato and others 2003), but extragonadal teratomas have also been reported (Williams and others 2001, Gurfield and Benirschike 2003). There are few descriptions of teratoma within the veterinary literature; cases are more widely described in human medicine. Among the domestic animal species, teratomas have been more frequently described in horses, and are considered extremely rare in other animals (Nielsen and Kennedy 1990, Kennedy and Miller 1993). Teratomas constitute almost 2 per cent of all primary canine ovarian tumours (Sforna and others 2003). Recently, cases of teratoma have been described in cats (Basaraba and others 1998, Sato and others 2003), dogs (Nagashima and others 2000, Yamaguchi and others 2004), African clawed frogs (Xenopus laevis) (Cheong and others 2000), domestic ferrets (Williams and others 2001), and a cynomolgus monkey (Toyosawa and others 2000). This short communication describes the ultrasonographic, gross and microscopic features of a teratoma in a bitch. A two-year-old German shepherd bitch weighing 28·6 kg was admitted to the SOS Animal veterinary hospital in late September 2004, with a history of sudden reduction of physical activity, lethargy and a marked increase in the size of the abdomen. The owner reported that he had noticed an unusual increase in the size of the dog’s abdomen almost one year previously, but since there was no apparent discomfort and the animal maintained its routine activities, veterinary advice had not been sought. The owner stated that the size of the dog’s abdomen had become remarkably enlarged during the 30 to 40 days before presentation to the hospital. The dog was an active participant in, and a winner of, various sporting competitions. Physical examination of the dog on arrival at the hospital was unremarkable; the animal was extremely active and its respiratory and cardiac functions were considered normal.Biochemical evaluations revealed a mild increase in the serum urea (14·28 mmol/l, reference range 3·14 to 9·24 mmol/l) and alanine aminotransferase (42 iu/l, reference range 0 to 40 iu/l) values.Palpation revealed a large abdominal mass located in the region of the right ovary. Ultrasonographic examination revealed a large, heterogenous, cystic, echogenic, rounded mass, which occupied the entire dorsal right-sided region of the abdominal cavity (Fig 1). An exploratory laparotomy revealed a large, firm, solid mass that replaced the right ovary; the left ovary was grossly normal. The mass caused a displacement of the intestines and other abdominal organs. An ovariohysterectomy was performed. The animal recovered, and at the time of writing was healthy and had resumed its sporting activities. The tumour was fixed in 10 per cent formalin solution and processed for routine histopathological evaluation. The mass weighed 3·3 kg and was 22 cm in diameter. Grossly, the tumour was encapsulated and firm; its surface was predominantly smooth and glistening, slightly irregular and cream to white in colour. Cross-section of the mass revealed an irregular surface that was predominantly covered by haired skin and cystic areas (Fig 2). These irregular, undulating, variably sized (1·5 to 2·5 cm in diameter), communicating cystic areas contained a watery to viscous, straw-coloured fluid. The cystic structures were embedded in a white to opaque, extensive interconnecting mass that consisted of a mixture of soft and firm connective tissue. Careful gross examination of the mass revealed apparently no ovarian tissue. Histologically, there was a marked variety of tissues within the tumour, each part of the tumour that was examined revealed a somewhat different histological architecture. Basically, the tumour was composed of a mixture of various embryonic tissues and cystic structures embedded in a muscular background. The outer margin of the tumour was lined by a squamous epithelium that demonstrated degenerative alterations, and all constituents of a normal cutaneous membrane (Fig 3a). Most of the large cystic areas were irregular in shape, filled with keratin and demarcated by a stratified squamous, keratinised epithelium, with hair follicles and sebaceous glands (Fig 3b). Smaller cystic areas were lined only by a stratified squamous epithelium without adnexal structures. The solid part of the tumour consisted of a large, dense sheet of a mixture of irregularly orientated smooth and skeletal muscle fibres and adipose tissue. Within the matrix of connective tissue there were islands of cartilaginous tissue, blood vessels and nerve fibres that were well differentiated but arranged in an ill-defined pattern (Fig 3c). In another area, a small cystic structure was lined by layers of plump, melaninfilled cells, probably representing elements originally from the neural crest (Fig 3d). Various glandular structures, comparable to those observed in the submucosa of the normal intestine, were observed surrounded by smooth muscle (Fig 3e). A large, extensive band of nervous parenchyma with prominent neurons, oligodendrocytes and astrocytes was also observed embedded within the muscular tissue (Fig 3f). The diagnosis of mature intraovarian teratoma was based on the identification of well differentiated tissues representing three primary embryonic germ cells (endoderm, ectoderm and mesoderm) within the same tumour. The origin Veterinary Record (2006) 158, 565-567
Databáze: OpenAIRE
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