Histological differentiation, histogenesis and prognosis of cutaneous angiosarcoma.

Background: Cutaneous angiosarcoma (CAS) is a rare, extremely malignant vascular tumor. The optimum treatment for patients with CAS has not been defined because of its exremely rarity. As prognostic factors in patients with CAS, tumor less than 5 cm in size has a better prognosis. Although tumor differentiation in other sarcoma is an important prognostic factor, tumor differentiation in CAS is not a prognostic factor. CAS is thought as a collection of hemangiosarcoma, lymphangiosarcoma, tumors which cannot be classified as of vascular and lymphatic origin, or mixed tumor of both. Histogenesis of CAS have not been clarified yet. We tried to classify histogenesis by immunohistochemistry and evaluate the prognosis among histogeneses.

Methods: Using immunohistochemistry, we classified histogenesis of CAS in 20 patients who visited Osaka City University Hospital between 1998 and 2008.

Results: From the results of immunohistochemical staining with CD34 and D2-40, histogenesis of CAS can be divided into vascular type (CD34 positive D2-40 negative), mixed type (CD34 positive D2-40 positive), and lymphatic type (CD34 negative D2-40 positive). Vascular type was found in 2 cases, mixed type in 5 cases, and lymphatic type in 13 cases. Survival rates were not significantly affected by histogenesis, however, survival rate of mixed type was better than those of others.

Conclusions: CAS can be divided into vascular type, mixed type, and lymphatic type based on immunohistochemistry. Because of a small group, we did not suggest that histogenesis of CAS was related with prognosis. We speculate that antiangiogenic agents might be important in the treatment based on histogeneses in CAS. In the future, further accumulation of chemotherapeutic cases might upgrade histogenesis classification as an important prognostic factor in the treatment of CAS.