Cutaneous hemangiosarcoma (HSA) appears to have a lower rate of metastasis and longer survival times compared with HSA in other locations. Studies have linked environmental factors (eg, UV radiation) to cutaneous HSA; others have linked the disease to thin hair coats and light pigmentation. Ninety-four dogs with histopathologically confirmed dermal HSA were included in this study. The majority (77%) developed locoregional recurrence, defined as any new tumor in the same regional area of skin clinically consistent with HSA. Whippets and pit bull terriers were the most common breeds diagnosed with dermal HSA. The ventrum was the most common location, resulting in a likelihood to develop additional tumors on the ventrum. Overall median survival time was 987 days; dogs with dermal HSA on the ventrum and solar histologic changes had longer survival times than those with dermal HSA in other locations. Dogs of nonpredisposed breeds without ventral involvement or solar changes, or with SC involvement, were more likely to develop metastasis. Results suggested that 2 forms of dermal HSA exist: a solar-induced form affecting thin-coated dogs with good prognosis, and an aggressive nonsolar form seen in nonpredisposed breeds in nonventral areas with thicker coating. Full staging is suggested in order to characterize the disease, as well as biopsies for UV-induced actinic changes.

The word hemangiosarcoma is typically associated with a negative outcome, but this report provided a reminder that it is possible to have favorable survival in a patient with a dermal lesion. Although prognosis should still be guarded, a full staging process with biopsy is recommended in order to make appropriate follow- up recommendations. Attention to the regions surrounding the sentinel lesion is necessary to monitor for regional recurrence. Full examination, diagnostics, and referral to an oncologist is recommended. —Heather Troyer, DVM, DABVP, CVA

Clinical outcome in 94 cases of dermal haemangiosarcoma in dogs treated with surgical excision: 1993-2007. szivek A, Burns Re, Gericota B, et al. VET COMP ONCOL 10:65-73, 2012.