Fibroadenomatoid hyperplasia of the breast (FAHB) is a rare benign breast lesion and its clinical features are similar to fibroadenoma and fibrocystic changes. FAHB has been previously termed sclerosing lobular hyperplasia, fibroadenomatosis, fibroadenomatoid change, or fibroadenomatoid mastopathy. Typically, FAHB is derived from stroma and epithelia. The pathologic characteristics of FAHB are microfocal lobulocentric proliferation of stroma accompanied by epithelial and myoepithelial components resembling similar histological changes, as found in fibroadenoma, apocrine hyperplasia, intraductal hyperplasia, and lobular hyperplasia. FAHB could be present as a localized or diffused pattern in pathology. Most cases show no well-circumscribed mass lesions and no apparent capsules; it is usually identified as an incidental finding in other benign lesions or in random sampling in cancerous breast tissues. FAHB is categorized as a benign proliferative breast disease and it has previously been reported; however, the authors believe this study may be the first case with two giant masses reported. Fiber adenoma hyperplasia is a rare cystic hyperplasia of breast pathology and its ultrasonographic manifestations are easily confused with breast cancer. Comparative MRI ultrasound analysis will help make the differential diagnosis.