Equine placental teratoma

Equine placental mixed germ cell tumor with metastasis to the foal

The placenta from an embryo transfer-recipient mare and live foal was examined. The placenta was effaced by multifocal masses, which ranged from less than 1 cm to 14 cm in diameter. The foal represented at 52 days for lethargy, ataxia, and urine dribbling; due to a poor prognosis, the foal was euthanized. At necropsy, the liver was effaced by multifocal, pale, irregular nodules. The lumbar vertebrae and other skeletal sites had multifocal lytic lesions. The placenta had 4 populations of neoplastic cells, including a spindle cell population, tall columnar and transitional epithelial cell populations, and an undifferentiated polygonal cell population. The foal's liver had similar populations and patterns of cells as those in the placenta. The lesion in the placenta and the masses in the foal were diagnosed as a mixed germ cell tumor and metastatic mixed germ cell tumor, respectively.

A case of umbilical cord teratoma in an aborted foal

A 16-year-old primiparous mare aborted an apparently normal fetus at 240 days of gestation. A large, oval mass, measuring approximately 20 cm × 30 cm × 20 cm, was detected attached to the umbilical cord of the fetus. On the cut surface, the mass showed multifocal cystic structures, foci of mineralization, and diffuse hemorrhages. Histological examination of the mass revealed haphazardly arranged cartilage, bone, mesenchymal stroma, adipose tissue, vascular structures, smooth muscle, ciliated epithelium, squamous cornifying epithelium, and undifferentiated germ cells with areas of necrosis and mineralization. The mass was diagnosed as an umbilical cord teratoma, which is an extremely rare tumor in human beings and, to the authors’ knowledge, has only described in the veterinary literature on one occasion.

A racing start in life? The hurdles of equine feto-placental pathology

Significant progress has been made in understanding and monitoring the causes of equine abortion over past decades. However, not all in utero pathology results in abortion. It has long been recognised that some in utero pathology, such as twinning or chronic placentitis, can result in the birth of live but growth-retarded foals and there is historical evidence that birth weight may influence future athletic performance. Clinical experience (e.g. from twins) and experimental studies (pony-Thoroughbred embryo transfer) have highlighted the importance of reduced functional placental area in limiting growth in utero in horses. Many other nonfatal in utero pathologies (e.g. umbilical cord-related circulatory compromise) can potentially affect either placental function or other organ systems. Their influence on the short- and long-term health of the foal and its future athletic performance is in many cases poorly documented or understood. This review summarises the main causes of in utero pathology and reflects on how these may potentially affect the foal if born alive, highlighting the need for long-term studies on this important subject.

Benign placental mass with fetal growth retardation in a bull mastiff

A 4-year-old bull mastiff presented due to premature labour. The referring veterinarian elected to perform a caesarian delivery and at the time of surgery a 4×4×2 cm round, smooth, red to tan, lobulated soft mass was identified attached to the allantoic surface of the zonary placenta of one pup. Microscopically, this mass was composed of loosely arranged confluent undulating cords of polygonal to columnar epithelioid cells separated by a fine fibrovascular stroma resembling the placental labyrinth. The labyrinthine structure and epithelioid nature of the cells suggested that the mass was of trophoblastic origin. Due to the non-invasive nature of the mass and relatively low mitotic activity, this proliferative trophoblastic mass was considered to be benign. The absence of morphological features supporting malignant behaviour and the recapitulation of the normal labyrinthine architecture led to the diagnosis of a trophoblastic hamartoma. To the authors' knowledge this is the first report of a placental hamartoma in the dog.

Teratoma of the umbilical cord in a giraffe (Giraffa camelopardalis reticulata)

A 12-year-old pregnant female giraffe (Giraffa camelopardalis reticulata) died approximately 2 months prior to her anticipated parturition date. At necropsy, a mass measuring approximately 20 x 36 x 20 cm was observed, attached to the umbilical cord, the latter being otherwise normal in appearance. Histologically, the mass contained 3 germinal tissue components with areas of squamous epithelium, respiratory epithelium, primitive neural tissues, glial tissue, peripheral nerve, adipose tissue, cartilage, and smooth muscle. Based on these findings, the tumor was diagnosed as a teratoma originating from the umbilical cord. This is possibly the second reported case of umbilical cord teratoma in animals.