A retrospective clinicopathologic study of 212 dogs with cutaneous hemangiomas and hemangiosarcomas.

The relationship between skin pigmentation and piliation and the development of hemangiomas and hemangiosarcomas in the dermis and subcutaneous tissue was studied in 212 dogs. These 212 dogs had a combined total of 306 tumors; 38 of these 212 dogs had two or more of the same tumor in a different location or a combination of hemangioma and hemangiosarcoma. The average age of the dogs at the time of excision of these tumors was greater than 10 years. There was no sex predilection for the presence or absence of tumors. Cutaneous hemangiomas (73%) were more common than cutaneous hemangiosarcomas (27%). Hemangiomas had no predilection for dermis (51%) or subcutaneous tissue (47%), but hemangiosarcomas had a marked predilection for dermis (73%) over subcutaneous tissue (7%). Dogs with short hair coats and lightly pigmented skin had more hemangiomas and hemangiosarcomas of the dermis (65%) than did dogs with variable length hair coats and pigmentation (28%). Dogs with short hair coats and lightly pigmented skin had fewer hemangiomas and hemangiosarcomas of the subcutaneous tissue (10%) than did dogs with variable length hair coats and pigmentation (22%). Dogs with short hair coats and lightly pigmented skin also had more hemangiomas and hemangiosarcomas of ventral glabrous skin (65%) than did dogs with variable length hair coats and pigmentation (22%). In addition, there was no predilection of subcutaneous hemangiosarcoma for haired (33%) versus glabrous (33%) skin, but dermal hemangiosarcoma had a marked predilection for the glabrous skin (63%) when compared with haired skin (10%). The increased incidence of dermal hemangiomas and hemangiosarcomas in ventral glabrous skin suggests an association between solar radiation and the biologic properties of glabrous skin in the genesis of these tumors.