Parosteal lipoma of humerus—A rare case
This study reports the case of a 65-year old woman with a big mass on the posteromedial aspect of the right upper arm since 1 year (admitted on 05/07/2013). The swelling was slow growing, painless, soft, nontender, immobile, with well defined margins and no fixity to skin. She had no complaints of pain or restriction of movements. She had no history of trauma.\nOn Roentgenogram of right humerus there was an evidence of ill defined soft tissue swelling in the upper arm posteromedially with radiopacity in continuation with the surface of humerus suggestive of bony excrescences (a).\nMRI right shoulder joint (plain + contrast) revealed a large 13 cm × 5 cm × 8 cm well defined, nonenhancing, lobulated, heterointense, predominantly fat intensity lesion with a small area of chondroid component measuring 2 cm × 1.6 cm in posteromedial aspect of the proximal right humerus, seen completely separate from the adjacent muscles (a and b).\nThe patient underwent surgery under general anesthesia. Vertical elliptical incision was taken over the posterior border of the right upper arm over the tumor. The tumor was under the lower part of deltoid which formed the roof near the upper end of humerus, between the long and medial heads of triceps muscles (a and b). 6 cm × 5 cm × 5 cm sized part of the tumor was under the long head of triceps displacing it medially along with radial nerve and vessels. 7 cm × 6 cm × 3 cm sized part of tumor was under the medial head of triceps displacing it laterally. The tumor was excised undocking the periosteal attachment (a). After hemostasis, wound was closed with a suction drain in situ. The specimen (a) weighed 250 g. Postoperatively a shoulder sling was given for 3 weeks to prevent any inadvertent fracture following the use of osteotome over the humerus during the surgery. Sutures were removed on postoperative day 10. Postoperative course was uneventful. Postoperative X-ray (b) of right humerus was normal and showed no bony excrescences.\nOn gross pathology, the lesion was multilobulated, well circumscribed and irregular mass of size 12 cm × 5 cm × 8 cm with a bony part measuring 2.5 cm × 2 cm × 1 cm. Cut surface was soft, yellowish and homogenously greasy (a).\nOn histopathology (b), the lesion was composed of mature lipocytes that had an intimate relationship with the periosteum, consistent with parosteal lipoma. No cellular atypia or lipoblasts were seen.