Histological and immunohistochemical prognostic factors of primary angiosarcoma

Angiosarcoma is a malignant vascular endothelial neoplasm with various histological patterns. Despite its highly malignant potential, histological prognostic prediction has not been adopted for angiosarcoma. This study aimed to establish a method of predicting the prognosis of primary angiosarcoma. Formalin-fixed, paraffin-embedded samples from 104 primary angiosarcomas were prepared. All the cases were reviewed based on histological examinations with H&E staining. Because the French Fédération Nationale des Centres de Lutte Contre Le Cancer system (FNCLCC) is not adopted for angiosarcoma, we experimentally established a modified version of FNCLCC. Immunohistochemical staining for ERG, CD31, CD34, D2-40, HHV-8, p16, C-MYC, and p53 was performed. Fluorescence in situ hybridization (FISH) was performed for 31 cases to assay c-MYC gene amplification. Multivariate analysis revealed that age (> 70 years old) (p = 0.0011), non-cutaneous angiosarcoma (p = 0.0265), metastasis on diagnosis (p < 0.0001), size ≥ 5 cm (p = 0.0388), no taxane chemotherapy (p = 0.0388), strong nuclear atypia (p = 0.0087), and the presence of luminal structure in ≥ 50% of the tumor volume (p = 0.0009) were independent poor prognostic factors. Among angiosarcomas with luminal formation, mFNCLCC scores were significantly correlated with a poorer prognosis. The overexpression of p16 was associated with less luminal formation (p = 0.0192). Immunohistochemical analysis of C-MYC showed a moderate level of concordance with FISH (Kappa value = 0.45). This study suggested that luminal formation and nuclear atypia may be poor histological prognostic factors of angiosarcoma and that mFNCLCC would be useful for predicting the prognosis of angiosarcoma with luminal formation.