J Korean Soc Magn Reson Med.  2010 Dec;14(2):134-138. 10.13104/jksmrm.2010.14.2.134.

MR Imaging Findings of Parosteal Lipoma: Case Report

• Bae HJ
• Hong SJ
• Kim Y
• Kang EY
• Kim HJ
• Ryu YJ
• Jung WY

• KMID: 2206911
• DOI: http://doi.org/10.13104/jksmrm.2010.14.2.134

Abstract

Parosteal lipoma is a rare benign tumor containing mature adipose tissue having an intimate relationship to the periosteum. Characteristically, this tumor presents as a lipomatous mass adjacent to bone, eliciting variable reactive changes in the underlying cortex. We report a case of parosteal lipoma of the foot. The MR findings consisted of juxtacortical lipomatous mass abutting to bony protuberance, with internal fibrous striations, and osseous reaction in the adjacent bone. By the aid of multiplanar imaging capability, high spatial and contrast resolution of MRI, characteristic features of parosteal lipoma can lead to diagnosis on imaging.

Keyword

Fatty neoplasm; Lipoma; Magnetic resonance imaging (MRI)

MeSH Terms

Adipose Tissue
Foot
Lipoma
Periosteum

Figure

• 

  Fig. 1 A 48-year-old female patient with parosteal lipoma in the right foot. (a) Lateral radiograph of the right foot shows an irregular bony protrusion from right 5th metatarsal base with surrounding low-density soft tissue mass-like lesion (arrows). Non-enhanced coronal T1-weighted (b), axial T2-weighted (c) MR images show a multi-lobulated well-marginated high signal intensity mass (asterisks) with several thin low signal striations(open arrows) in the plantar surface of right mid foot just deep to the flexor digitorum brevis muscle. (d) Fat-suppressed coronal T2-weighted image shows low signal intensity conversion in almost whole area of the mass (asterisks) and high signal thin striations (open arrow). (e) Post-contrast fat-saturated coronal T1-weighted image shows minimal enhancement in the internal striations (open arrow) without demonstrable enhancing solid portion in the mass. A focal nodular enhancement is seen in the junction between the bony protuberance and the mass (arrowheads). A peripheral ill-defined subtle enhancement is seen in the mass which corresponds to the high signal portion on pre-contrast fat-suppressed T2-weighted image (thick arrows in Fig. b, d, e), representing secondary focal cystic change. The mass shows irregular attachment (arrowheads in Fig. b, d, e) to the cortical based bony excrescence arising from the inferior aspect of the 5th metatarsal base (B on Fig. b-e). Medullary continuation between bony protuberance and the 5th metatarsal bone is not definite on the precontrast T1-weighted coronal image, although suspected in the other pulse sequences (thin arrows in Fig. b, d, e). Focal cortical erosion is combined in the inferomedial side of the 5th metatarsal base (curved arrows in Fig. b-e). (f) Photomicrograph (×40, H-E stain) reveals the junction between bony protuberance (B) and the lipoma (L) with reactive cortical hypertrophic changes, cortical erosions (arrow), and fibrovascular proliferation of the intervening periosteum (P).

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