Cutaneous haemangiosarcomas are a mesenchymal tissue neoplasm (soft tissue tumor). They are also known as connective tissue tumors, which are relatively frequent in domestic animals and have a high incidence in some species. In cats, connective tumors occupy the second position of all neoplasms diagnosed in this species, having an incidence of 17 in every 10,000 clinical cases^[1]. Feline cutaneous hemangiosarcoma are a rare skin disease, also known as malignant hemangiothelioma or angiosarcoma. These are a malignant neoplasm that arises from vascular endothelial cells. As might be expected of a tumor originating in the blood system, they are highly malignant and can be found almost anywhere on the body^[2].

This tumor is similar to squamous cell carcinoma in that it is actinic, or sunlight-induced. Cutaneous hemangiosarcoma occurs commonly in cats from areas where actinically induced tumors are common^[3], but not in cats from the northeastern United States ^[4]. They can also occur as a variant of the feline fibrosarcoma complex.

In felines, they are usually solitary tumors with a predilection for the head (especially eyelids), ear tips, nasal planum, and non-pigmented skin. Feline, as well as some canine, cutaneous hemangiosarcomas are similar to squamous cell carcinoma in that they can be actinic or sunlight-induced. The etiology of hemangiosarcomas is unknown, but reports in human cases suggest a correlation between hemangiosarcomas and exposure to carbon dioxide, arsenicals, or vinyl chloride.

In general, the biological behavior of this neoplasm is highly aggressive with most forms of the tumor metastasizing early in the disease process. Visceral hemangiosarcomas are highly aggressive tumors with a poor prognosis. Death is often associated with rupture of nodules or masses and resultant hemoabdomen or hemo-pericardium. Cutaneous hemangio-sarcomas are less aggressive than their visceral counterparts with lower metastatic potential and longer survival times^[5].

Clinical signs

Feline hemangiomas appear as solitary tumors in the dermis and subcutis without any site predilection. In contrast, feline hemangiosarcomas may have a predilection for the head (ear tips, nasal planum) and also have a predilection for non-pigmented skin. They can also occur in internal organs such as the intestine or heart^[6][7]. They are usually solitary tumours.

Hemangiosarcomas can be diagnosed cytologically on the basis of the appearance of fine-needle aspirates or impression smears. The neoplastic cells are similar to those in other sarcomas, as they are often spindle-shaped, but vary considerably in shape. These spindyloid cells often have large nuclei with a lacey chromatin pattern, one or more nucleoli, blue-grey vacuolated cytoplasm, and an increase in mitotic figures. Breed and clinical signs may also suggest a diagnosis of hemangiosarcoma. Histo-pathology is confirmatory^[8].

Clinical diagnostic points:

• CBC: mild to severe anemia, leukocytosis, thrombocytopenia
• Chemistry: increased hepatic enzymes
• Abdominal radiographs: Appearance of an intra-abdominal mass
• Thoracic radiographs: pulmonary nodules, right atrial enlargement
• Abdominal ultrasound: splenic mass, peritoneal effusion, hepatic nodules, enlarged mesenteric lymph nodes

Dogs and cats with cutaneous or subcutaneous hemangiosarcoma are usually evaluated for a nodule that is generally a single, well-defined mass which is red/brown to black, soft to firm, and may exude blood when cut. The blood disorder that commonly accompanies hemangiosarcoma is disseminated intravascular coagulopathy (DIC). This process involves blood clotting that occurs inappropriately inside the blood vessels. In DIC, blood clotting factors are consumed rapidly resulting in platelet deficiencies, increased clotting times, decreased fibrin content, and increased fibrin degradation products. DIC can commonly be the cause of death in many cases of hemangiosarcoma^[9].

Histologically, haemangiosarcomas are characterized by spiral proliferations around blood vessels, with a typical “fingerprint” arrangement of the cells disposed concentrically around the capillaries that are collapsed (Fig. 5.32.). Capillaries are frequently hyalinized. These images are not present in the whole tumor mass, but fascicular proliferations similar to connective tumors with fusiform cells can be noted. These cells are thickened in their middle portion, due to the central ovoid nucleus, with obvious nucleoli, and the cytoplasm, eosinophilic, is in a low amount. Multinucleated cells are exceptional. The cells, but especially the morphology of the nuclei, allow the differentiation from fibroblasts or other mesenchymal cells, which are in general more flattened and elongated [30, 124, 146]. Perivascular lymphocytic infiltrations have been found in 1/4 of the diagnosed hemangiopericytomas. The collagen stroma amount varies widely, sometimes being abundant; necrotic microfoci may be present².

Treatment

Surgical excision of cutaneous hemangioma usually has a good prognosis, although local recurrence following surgical excision of cutaneous hemangiosarcoma is frequent. Metastasis appears to be rare. It is therefore appropriate to treat this tumor as a soft-tissue sarcoma in cats, with aggressive initial surgery as the best therapeutic approach.

In a study by McAbee et al (2005), aggressive surgical excision of the tumor was attempted in 10 cats. A complete surgical excision was achieved in five of the 10 cats. Median survival times were statistically longer in cats that underwent surgery versus cats that did not. Cats with cutaneous HSA treated with aggressive surgical excision of their tumors may have a good long-term prognosis.

Surgical excision is the preferred choice of treatment for dermal or subcutaneous hemangiosarcomas. Various chemo-therapeutic regimes have been attempted on dogs with multicentric visceral with little success. Survival times vary with the location and stage of the tumor but, in general (with exception of dermal hemangiosarcomas), are quite short. Studies have shown survival times of 20-60 days following detection of the tumor, with a one year survival rate in less than 10% of patients.

References

1. ↑ Carpenter JL, Andrews LK, Holzworth J (1987) Tumors and tumor-like lesions. In: Diseases of the cat: Medicine and Surgery, ed Holzworth J, WB Saunders Co, Philadelphia, PA, pp. 406-596, 1987.
2. ↑ Kraje, AC, Mears, EA, Hahn, KA, McEntee, MF, Mitchell, SK (1999) Unusual metastatic behavior and clinico-pathologic findings of eight cats with cutaneous or visceral hemangio-sarcoma. JAVMA ‘214:670-672
3. ↑ Chun R (1999) Feline and canine hemangiosarcoma. Compendium Cont Ed for Prac Vets 21: 622-629.
4. ↑ Scavelli TD, Patnaik AK, Mehlaff CJ, Hayes AA (1985) Hemangiosarcoma in the cat: retrospective evaluation of 31 surgical cases. J Am Vet Med Assoc 187: 817-819
5. ↑ Ogilvie, GK (2002) Ten best kept secrets for treating cats with cancer. WSAVA 2002 Congress.
6. ↑ Sharpe, A, Cannon, MJ, Lucke, VM, Day, MJ (2000) Intestinal hemangio-sarcoma in the cat. Clinical and pathological features of four cases. J Small Anim Prac 41:411-415.
7. ↑ Merlo, M (2002) Primary right atrium haemangiosarcoma in a cat. J Feline Med and Surg 4: 61-64.
8. ↑ McAbee, KP, Ludwig, LL, Bergman, PJ & Newman, SJ (2005) Feline cutaneous hemangiosarcoma: a retrospective study of 18 cases (1998-2003). Journal of the American Animal Hospital Association 41(2):110-6
9. ↑ Miller MA, Ramos JA, Kreager JM (1992) Cutaneous vascular neoplasia in 15 cats: Clinical, morphologic and immunohistochemical studies. Vet Pathol 29: 329-336, 1992.