Horse Case

Age: 2 Y
Gender: FEMALE


Slow growing, cutaneous mass on dorsal carpus left front – excised entirely.

Click here for the IDEXX Pathology Report on this case.

Microscopic Description:

Haired skin: Within the dermis, there is an expansile mass comprised of multinodular proliferations of blood filled, vascular spaces lined by single layers of well differentiated endothelial cells. There is intervening fibrous tissue noted. There are pericytes located concentrically around the vascular channels.


Haired skin: Hemangioma, capillary, multinodular, completely removed


Completely Removed.


Hemangiomas account for 0.6-4% of all equine skin neoplasms. These are benign neoplasms arising from the endothelial cells of blood vessels. The cause of most hemangiomas is unknown. There are no apparent sex predilections. Although hemangiomas can occur at any age, they are often seen in horses less than 1 year of age and may be congenital. Anecdotal reports suggest that congenital hemangiomas are particularly common in Arabians. The lesions are usually solitary and may occur anywhere, but they most commonly affect the distal limbs. In a report of three young Thoroughbreds, hemangiomas were described as solitary subcutaneous swellings on the dorsal carpal region. The lesions may be: (1) well circumscribed, nodular, firm to fluctuant, bluish-to black; or (2) well circumscribed, plaquelike, hyperpigmented, hyperkeratotic to verrucous. Lesions vary from 4- 30 cm in diameter. Excision is typically curative.


Equine Dermatology. Scott DW, Miller WH. 2nd ed. 2011.

Image Notes:

Image 1:  Low magnification view of the entire tumor (as submitted).

Image 2:  Medium magnification view demonstrating the multinodular proliferations of blood filled, vascular spaces.

Image 3:  Higher magnification view demonstrating the endothelial cells lining the vascular spaces.

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