Introduction:
Rare benign tumor associated with periosteum
Seering (1836), initially referred to as periosteal lipoma. Parosteal lipoma was suggested by Power (1888)
0.3% of lipomas
Most commonly in femur, proximal radius. Also in tibia, humerus, scapula, clavicle, ribs, pelvis, metacarpals, metatarsals, mandible, skull.
Slow growing painless immobile mass, not fixed to the skin
Nerve compression is commonly seen with forearm lesions
Usually firmly adherent to the underlying cortex at the site of surface bone production
Radiograph:
Bowing of bone or cortical erosion
CT:
–60 and –125 HU, septations, prominant osseous protuberances, mild enhancement in fibrous tissue
MR:
Juxtacortical heterogenous lobulated septated mass with signal similar to subcutaneous fat, intermediate signal on T1 and high on T2 represent cartilaginous components. Areas of bone production surrounded by lipomatous component is better seen. Adjacent muscle atrophy is best seen on T2
Bone scintigraphy:
Increased uptake
Treatment:
Surgically resected - encapsulated and strongly adherent to periosteum needs subperiosteal dissection, osteotome or segmental bone resection. Local recurrence is unusual, no malignant transformation
References:
Murphey MD et al. Benign Musculoskeletal Lipomatous Lesions. RadioGraphics 2004;24:1433-1466
