A large breast lump causing a diagnostic dilemma.

Lipomas are the most frequent mesenchymal tumors consisting of mature fat cells and are usually benign. They represent approximately 4-5% of all benign tumors that occur in human body. They can sometimes present very large sizes in their localization and are referred to as "giant lipomas". In this article, the authors report an unusual case of a right breast giant lipoma causing diagnostic dilemma. A 62-year-old woman was referred to the present hospital with a complaint of a sudden chest asymmetry of the right breast increasing at the connection of the pectoralis muscle. Ultrasonography revealed breast tissue involution (ACR 1). Specifically, the ultrasound findings were mostly compatible with lipid mass (lipoma) and areas with cystic necrosis. The findings from digital mammogram were not conclusive compared with ultrasound examination. Moreover, the results from the breast MRI were contradictory and other diagnosis was evinced. The patient underwent wide-surgical excision and reconstruction and had an excellent postoperative issue. According to the final histopathological examination, the tumor measured 17 cm and was covered by a thin membranous capsule. Furthermore, it had the appearance and composition of adipose tissue. In conclusion, according to the authors' view, this case is rare due to its challenging size and the difficulty in differential diagnosis.