Hepatoblastoma in a foal

Equine Gastrointestinal Neoplasia

Gastrointestinal neoplasia is uncommon in horses. Clinical signs can be vague and advanced testing, including biopsy, exploratory surgery, and/or advanced imaging may be required for diagnosis. Prognosis varies by location, organ involved and is frequently poor to grave.

Hepatic neuroendocrine carcinoma with metastases to the lymph nodes in a sika deer (Cervus nippon yakushimae)

A 26-year and 6-month-old male sika deer that was kept at the Showa Park, Tokyo, Japan, collapsed and died of severe disease wasting and severe tabefaction. Grossly, numerous masses, 0.3–1.0 cm diameter, were dispersed throughout the liver. The multiple masses were composed of tumor cells, which had hypochromatic nuclei and abundant faintly eosinophilic cytoplasm, arranged in nests of various sizes. Immunohistochemically, tumor cells were positive for cytokeratin, chromogranin A, synaptophysin and gastrin. Ultrastructurally, the cytoplasm of the tumor cells contained abundant membrane-bound electron-dense granules. A metastatic lesion was observed in the renal, hepatic and pancreatic lymph nodes. On the basis of these findings, this tumor was diagnosed as a neuroendocrine carcinoma with metastases to the lymph nodes.

Erythrocytosis and fatigue fractures associated with hepatoblastoma in a 3-year-old gelding

Hepatoblastoma was diagnosed in a 3-year-old Thoroughbred gelding presented with forelimb lameness with bilateral fatigue fractures of the proximal third metacarpal bones. An abdominal mass was detected on ultrasound examination of the abdomen. Absolute erythrocytosis was diagnosed after clinical and haematological evaluation. The fractured metacarpal bones were surgically removed but complications after surgery were fatal. The liver mass was diagnosed as a hepatoblastoma based on histology and immunochemical staining. The combination of hepatoblastoma and fatigue fractures has not been described previously in horses. A potential link between the hepatic and orthopaedic pathologies is hypothesised.

Spontaneous pulmonary co-metastasis of hepatoblastoma arising within a hepatocellular carcinoma in an aged C57BL/6J mouse

Murine hepatoblastoma (HB) is a rare spontaneous tumor with controversial histogenesis. It mainly occurs in aged males, frequently in close association with preexisting hepatocellular neoplasms. The present work describes a spontaneous HB arising within a hepatocellular carcinoma (HCC) in a 22-month-old male C57BL/6J mouse. The mouse also developed pulmonary co-metastases with either tumor components physically associated within the same metastatic foci. Microscopically, the HB consisted of a densely cellular neoplastic growth composed of palisades and perivascular pseudorosettes of poorly differentiated primitive cells, with a scant amount of cytoplasm, elongated hyperchromatic nuclei, and a high mitotic rate, whereas the hepatocellular carcinoma was composed of solid areas of neoplastic hepatocytes. Both in primary tumors and their metastases, β-catenin immunohistochemistry revealed a strong nucleocytoplasmic signal in HB cells, while neoplastic hepatocytes displayed a delicate membranous staining pattern. These findings suggest that the Wnt/β-catenin oncogenic pathway is upregulated in murine HB but not in the co-existing HCC, thus providing some insights into their divergent pathogenesis. Coexisting murine HB and HCC have been demonstrated to be completely distinct entities including origin, mutational landscape, and molecular profile. In this context, they might be regarded as collision tumors because of their intimate association, unique histologic features, and distinct immunohistochemical patterns. Nevertheless, the nature of their coevolution and progression to a co-metastatic phenotype reflects a close interdependence and support the overall idea that HB's origin and progression might be promoted by not otherwise specified paracrine stimuli provided by the concurrent hepatocellular tumor (the so called "interaction theory").

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.

Equine Primary Liver Tumors: A Case Series and Review of the Literature

Hepatoblastoma (HB) is an uncommon pediatric liver tumor in humans and horses. In humans, HB is most frequently diagnosed in fetuses, neonates, and young children, whereas hepatocellular carcinoma (HCC) affects juvenile and adult humans. Hepatoblastoma in the horse is rare, with only 9 reported cases. Affected horses ranged in age from late-term aborted fetuses to 3 years. The current study describes 3 new cases of primary liver tumors in horses and reviews findings in relation to other reports on this condition. Tumors classified as HB were identified in a male Standardbred aborted fetus and in a 4-year-old Thoroughbred filly. Hepatocellular carcinoma was diagnosed in a 15-month-old Paint filly. In the Standardbred fetus, the tumor was only present in the liver. In the Thoroughbred and Paint fillies, primary tumors were in the right liver lobe and at the hilus, respectively, and there were metastases to other lobes (HB) and mesenteric lymph nodes (HCC). Tumors were sharply demarcated from adjacent tissue, nonencapsulated, compressive, and invasive. Consisting of cords and nests, or disorganized sheets of epithelial cells, tumors had variable stromal and vascular components. The fetal tumor contained areas of smaller, less differentiated cells with a pronounced mesenchymal component interpreted to be embryonal hepatic tissue. Diagnoses were based on tumor histomorphologic features, resemblance to hepatocyte developmental stages, age of the animal, and patterns of metastasis. Tumors classified as HB were α-fetoprotein immunoreactive. Primary hepatic tumors in the horse are diverse in morphology and include subtypes compatible with classification criteria applied to human tumors.

Erythrocytosis and pleural effusion associated with a hepatoblastoma in a Thoroughbred yearling

A 10-month-old Thoroughbred filly was presented with a 2-month history of recurrent fever and pleural effusion. Major clinical findings were pyrexia and congested mucous membranes. Clinical pathology tests revealed an erythrocytosis, hyperfibrinogenaemia and hyperglobulinaemia. Pleural fluid was seen on ultrasonographic examination of the thorax and analysis of a thoracocentesis sample indicated a lymphocytic, modified transudate. A transtracheal aspirate was normal. The erythrocytosis persisted despite IV fluid therapy. Arterial blood gas analysis and bone marrow aspirate were normal. These findings were indicative of secondary inappropriate erythrocytosis. Ultrasonographic examination of the abdomen showed a large encapsulated heterogeneous mass in the left lobe of the liver. Histopathological evaluation of a biopsy of the mass was indicative of a hepatic carcinoma. The filly was euthanased and necropsy confirmed the presence of a hepatic tumour with no evidence of systemic metastasis. Further histopathological evaluation confirmed the tumour to be an embryonal macrotrabecular epithelial-type hepatoblastoma, a type of hepatoblastoma that has not previously been reported in a horse.

Three equine cases of mixed hepatoblastoma with teratoid features

Hepatoblastoma was diagnosed in 3 Thoroughbreds at the University of Kentucky Livestock Disease Diagnostic Center (LDDC) since 1997. Case #1 involved a fetus with a well-demarcated, multilobulated, solitary mass that extended from the left liver lobe. Case #2 was observed in a neonate with a primary hepatic mass and multiple metastases in the skin, brain, meninges, and stylohyoid bone. Case #3 was a solitary hepatic mass incidentally discovered in a neonate at necropsy. Microscopically, the masses were similarly composed of sheets and cords of fetal and embryonal epithelial cells that frequently formed sinusoid-like structures. Intermixed with the neoplastic epithelial cells were variable amounts of hemorrhage, necrosis, osteoid, and bone. Immunohistochemically, the epithelial cells stained variably positive for alpha- fetoprotein, frequently positive for vimentin, and occasionally positive for cytokeratin. All 3 cases were diagnosed as mixed hepatoblastoma with teratoid features.

Congenital tumours and tumour-like lesions in domestic animals. 3. Horses. A review

The literature on congenital tumours and tumour-like lesions in horses was reviewed. Included were embryonic tumours and teratomas. Special attention was paid to the ubiquitous adenomatous hyperplasia of the placenta. It appears that temporal teratomas, interstitial hamartomas and placental adenomatous hyperplasia are unique in the horse. Benign teratoma of the undescended testis is far more frequent in the horse than in other species. In horses, as in calves and pigs, congenital skin tumours were of papillomatous, vascular and melanocytic types. The sporadic occurrence of congenital tumours in the horse did not provide an etiologic or pathogenetic clue. The possibility of oncogenic viruses in cases of congenital skin papilloma or malignant lymphoma could neither be proven, nor be excluded. Hereditary tumours were not encountered.