Vulvar epithelioid hemangiosarcoma with solar elastosis in a mare.

The study presents a case of a 15-year-old female horse diagnosed with a rare form of cancer, ‘hemangiosarcoma’, in the vulvar area, associated with significant solar elastosis, a change in skin tissue due to sun exposure.

About the Case

• A 15-year-old gray Appaloosa mare (a breed of horse) was reported to have a mass growing over the right dorsal commissure of its vulva. This lump had been growing for the past 7 months.

Diagnostic Procedure

• Samples from the mass were subjected to histopathological examination. This includes looking at sections of the suspected tumor under a microscope to observe the structure and nature of the cells.
• The researchers also conducted tests for factor VIII-related antigen, vimentin, and used the Verhoeff-van Gieson stain. These are special markers and stains used to differentiate certain types of cells or tissues and are particularly useful in diagnosing specific types of cancer. Factor VIII-related antigen is specific to the cells lining the blood vessels (endothelial cells). Vimentin is a protein expressed in a wide range of mesenchymal cell types like fibroblasts and endothelial cells.
• This type of staining and the testing for these specific markers and antigens led to a diagnosis: the mass was a hemangiosarcoma, a rare and aggressive form of cancer that originates in the cells lining blood vessels.

Solar Elastosis

• Along with the diagnosis of hemangiosarcoma, the horse was also found to have marked solar elastosis. Solar elastosis is a condition where the skin undergoes changes due to prolonged exposure to the sun. In other words, it is the breakdown or damage of elastic tissue in the skin due to sun damage. Common in humans, this is also reported in animals.
• The presence of solar elastosis in this case indicates the potential influence of sun exposure on the skin condition and formation of the tumor. It is unclear whether the solar elastosis was a factor contributing to the development of the hemangiosarcoma in this mare, but it was a concurrent condition.

In conclusion, this study reports a rare diagnosis of hemangiosarcoma in a mare with significant solar elastosis. The researchers used advanced histopathological techniques and specific cellular staining to confirm the diagnosis in absence of clinical features.