Lump on Back: A Rare Case of Parosteal Lipoma of Scapula

Abstract

Lipomas are benign tumors of mature adipose tissue which can occur in subcutaneous, intramuscular, intermuscular, parosteal, and intraosseous compartments. Parosteal lipoma is a rare type of lipoma, accounting for less than 0.1% of primary bone neoplasms and 0.3% of all lipomas. Parosteal lipomas commonly arise in the femur and extremities. Around 150 cases have been reported in English literature with scapula being a rare site of involvement. They are known to be associated with underlying bony changes like focal cortical hyperostosis, pressure erosion of the underlying bone, and bowing deformity or with underlying osteochondroma. We report a rare case of a parosteal lipoma arising in the scapula with a bony excrescence in a 38-year-old male.

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“…The bone component presents low signal in T1 and T2. MRI is also able to identify muscle atrophy and signs of compression of adjacent neurovascular bundles [6,[10][11][12]. PL can cause peripheral nerve compression, and there are reports in the literature of involvement of the radial, sciatic, ulnar and median nerve.…”

“…Interestingly, the anchoring effect of the bone fixation site may predispose these pars plana LI to the mass effect and to the nerve impact, unlike the soft tissue LI pattern, which expand along the path of least resistance [2]. Post-contrast images may reveal enhancement at the interface of mass and bone protuberance, inferring in the possibility of fibrous tissue border or other soft tissue reactional changes [7,10,11].…”

Parosteal Lipoma in the Scapula Associated with a Osteochondroma- A Rare Case

“…Interestingly, the anchoring effect of the bone fixation site may predispose these pars plana LI to the mass effect and to the nerve impact, unlike the soft tissue LI pattern, which expand along the path of least resistance [2]. Post-contrast images may reveal enhancement at the interface of mass and bone protuberance, inferring in the possibility of fibrous tissue border or other soft tissue reactional changes [7,10,11]. In our case, near the lipomatous lesion, in the inferior angle of the right scapula, there was also a bone excrecence with characteristics compatible with OC.…”

Parosteal Lipoma of Femur—A Case Report

“…The bone may be normal inspite of the close relationship of lipoma with the periosteum [12] [13], but reactive changes in the adjacent bone [14] such as bone deformity, cortical erosion, and bony hyperostosis [15] [16] had been detected. More than half of parosteal lipomas presenting bone reactions are associated with hyperostosis [13] [17].…”

“…It is assumed that cortical hyperostosis can be explained by the contact of the lipoma with the bone [12] [18]. A possibility which could be caused by stimulation or irritation of the periosteum [19].…”