PRAME immunohistochemistry distinguishes breast secondary angiosarcoma from benign and atypical vascular lesions of the breast.

Abstract

Objective: We examined the utility of preferentially expressed antigen in melanoma (PRAME) immunohistochemistry (IHC) in distinguishing breast angiosarcoma from benign or atypical vascular lesions (AVLs) of the breast.

Methods: There were 26 breast angiosarcomas (24 radiation related and 2 primary), 6 radiation-related AVLs of the breast, and 16 other benign vascular lesions of the breast retrieved from our institutional archive and stained with PRAME IHC.

Results: Twenty-four of 26 (92%) breast angiosarcomas were positive for PRAME with moderate to strong staining intensities (median HScore, 255 [range, 90-300]), while 0 of 22 benign or atypical vascular lesions of the breast were PRAME positive (sensitivity, 92.3% [95% CI, 75.9%-98.6%]; specificity, 100% [95% CI, 85.1%-100%]); c-MYC was positive in all angiosarcoma cases but showed weak staining in several cases (median HScore, 155 [range, 30-280]). PRAME was negative in 1 of 2 primary angiosarcomas and negative in only 1 of 24 secondary angiosarcomas of the breast. None of the benign or atypical vascular lesions was stained with PRAME.

Conclusions: It appears that PRAME expression occurs in a high proportion of radiation-related angiosarcomas and not in benign breast vascular lesions or AVLs. PRAME IHC is diagnostically useful in distinguishing benign from malignant vascular proliferations in patients with a history of radiation to the breast.