Track: Clinical Studies

Topic: Neoplasia,Carcinogensis,Tumor Biology

Abstract:

Diagnosing vascular lesions in the breast can be problematic, particularly when confronted with small samples in patients with prior radiation history. PRAME (PReferentially expressed Antigen in MElanoma) expression has been described in malignancies other than melanoma, including up to 66% of angiosarcomas. Benign vascular lesions typically exhibit circumferential positivity with Smooth Muscle Actin (SMA), likely indicating an intact population of pericytes. In this study we aim to demonstrate the utility of PRAME and SMA to differentiate benign vascular lesions from angiosarcomas in the breast. Cases of reactive angiomatosis (n = 2), hemangioma (n = 3, 1 from breast parenchyma), atypical vascular lesion (AVL) (n = 3), and angiosarcoma (n = 5, 1 from breast parenchyma) arising from the breast were selected and stained with SMA (ASM-1 clone) and PRAME (EPR20330 clone). Positive SMA is defined by complete circumferential staining of lesional vessels, whereas absent or incomplete circumferential staining is considered negative. PRAME is defined as being negative (0), or moderate-to-strong nuclear positivity in 1-25% (1+), 26-50% (2+), 51-75% (3+), or >75% (4+) of lesional cells. All 5 cases of angiosarcoma are negative for SMA and show 3-4+ reactivity for PRAME. Conversely, all benign vascular lesions including reactive angiomatosis and capillary hemangiomas (n = 5), as well as the AVLs (n = 3) show positive SMA expression and are completely negative for PRAME (0). We can conclude that in our limited case series PRAME and SMA are useful tools to distinguish angiosarcoma from benign vascular lesions and AVLs in the breast.

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Carlos Prieto-Granada, M.D.