Objective:

To analyze and summarize the imaging features of parosteal lipoma in order to improve the understanding of the disease.

Methods:

The clinical and imaging data of 4 patients with parosteal lipoma were analyzed retrospectively.

Results:

Among the 4 patients

there were 2 males and 2 females. The lesions originated in scapula

calcaneus

humerus and femur

respectively. The main clinical manifestation was a solitary and slow-growing painless mass. X-ray was characterized by parosteal transparent mass with adja

cent cortical hypertrophy and bony protrusion. On computed tomography (CT)

the lesions were quasi circular or lobulated

and performed as fat density with clear margin. The central part of the lesion showed antler-like or coral-like ossification

which was continuous with the thickened cortical bone or protrusion at the attachment. There could have bone erosion and destruction. On magnetic resonance imaging (MRI)

the lesions showed mainly high-signal on T1-and T2-weighted imaging

and low-signal on fat suppression sequence. Low-signal ossification and iso-signal fiber separation could be seen in the lesions

and fibrous capsule could be seen on the margin. The capsule and fiber separation were slightly enhanced after injection of contrast agent.

Conclusion:

Parosteal lipoma is a rare disease with characteristic imaging manifestations such as paraosseous fat density or signal mass with ossification and adjacent bone changes. Combined with CT and MRI

it can be correctly diagnosed before operation.