Positive FAPI PET/CT in a Bilateral Mammary Angiosarcoma Patient With Less Impressive FDG PET/CT Images.

Bilateral primary angiosarcoma of the breast is an extremely rare disease. We describe a case with bilateral angiosarcoma of the breast well visualized on 68Ga-FAPI PET/CT in a 30-year-old woman with a history of right breast-conserving surgery. However, the lesions are less impressive on 18F-FDG PET/CT. No additional findings including lymph node and distant metastases were noted. The patient underwent bilateral mastectomy, and histopathology revealed well-differentiated angiosarcoma that involved bilateral breast parenchyma and the left nipple. Our case illustrates that 68Ga-FAPI PET/CT can be more sensitive in detecting well-differentiated angiosarcoma of the breast.