Equine primary liver tumors: a case series and review of the literature.

The research article is about a study that uncovers three new cases of primary liver tumors (specifically, hepatoblastoma and hepatocellular carcinoma) in horses, comprehensively detailing their characteristics alongside a related review of literature.

Overview of hepatoblastoma and hepatocellular Carcinoma

• Hepatoblastoma (HB) and hepatocellular carcinoma (HCC) are two different types of liver tumors that mostly occur in children and adults, respectively. This paper investigates these tumors in horses, notably a rare occurrence with only nine reported HB cases in the literature.
• HB has been diagnosed in horses ranging from late-term aborted foetuses to three-year-old juveniles. HCC, on the other hand, was identified in a 15-month-old horse.

Study of New Cases

• The authors of the study identified three new cases of primary liver tumors in horses, two of which were classified as HB and one as HCC.
• The two HB cases were found in a male Standardbred aborted fetus and in a 4-year-old Thoroughbred female horse, while the HCC case was diagnosed in a 15-month-old Paint filly.

Tumor Location and Characteristics

• The tumors were discovered in different parts of the liver: the tumor in the Standardbred fetus was only present in the liver while in the Thoroughbred and Paint fillies, primary tumors were in the right liver lobe and at the hilus, respectively.
• The tumors exhibited metastasis, spreading to other lobes (in the case of HB) and to mesenteric lymph nodes (in HCC).
• These tumors were sharply demarcated from adjacent tissue, nonencapsulated, compressive, and invasive. They consisted of cords or disorganized sheets of epithelial cells, with varying extents of stromal and vascular components.

Diagnosis and Comparison with Human Tumors

• Diagnoses were made based on tumor histomorphologic features, resemblance to hepatocyte developmental stages, the age of the animal, and patterns of metastasis.
• Tumors classified as HB were found to be alpha-fetoprotein immunoreactive, meaning they contained a protein that’s often associated with fetal development.
• The authors concluded that primary hepatic tumors in horses are diverse in morphology and include subtypes that meet classification criteria used for human tumors, indicating potential parallels in the occurrence and development of these tumors across species.