Parosteal lipoma of the scapula: a case report.

A 59-year-old Chinese man with a history of follicular lymphoma presented in November 2015 with painless swelling in the right upper back. The patient had no history of trauma. Clinical examination revealed a mild non-tender prominence over the right scapula without palpable axillary lymph nodes. Musculoskeletal and neurovascular examinations were normal. Plain radiograph of the right shoulder showed a well-circumscribed radiolucent lesion in the body of the right scapula with an adjacent irregular osseous protuberance. Computed tomographic scan revealed a well-defined lipomatous subscapular lesion with internal calcific foci adjacent to the body of the scapula with juxtacortical bony excrescence (Fig 1a and b). There was no continuity with the medulla of the parent bone. The provisional diagnosis was lipoma. Because of the history of follicular lymphoma, 18F-fluorodeoxyglucose (FDG) positron emission tomography–computed tomography (PETCT) scans had been performed at regular intervals for 3 years; these scans incidentally showed a serial increase in the size of the right scapular lesion from 2.5 cm × 3.8 cm to 3.2 cm × 5.8 cm. No significant FDG uptake was seen (Fig 1c). Magnetic resonance imaging (MRI) scan performed for further characterisation showed a well-marginated 3.2-cm × 7.6-cm × 6.6-cm soft tissue mass beneath the subscapularis muscle abutting the subscapularis fossa (Fig 2). Signal intensity was predominantly identical in all pulse sequences to that of subcutaneous fat, suggestive of a lipomatous component. The central part of the lesion was heterogeneous in signal intensity, with T1-weighted and T2-weighted low signal structures extending and radiating from the bony scapula, corresponding to the bony protuberance seen on CT scan. Thin internal septa were noted within the lesion. No cortical or medullary continuation with the parent bone was evident. There was no gross invasion of the bony scapula. No muscle atrophy was seen to suggest nerve entrapment. While the imaging features were compatible with that of a parosteal lipoma, CT-guided biopsy of the lesion was subsequently performed for confirmation. Under local anaesthesia and CT guidance, the right scapular body was penetrated Hong Kong Med J 2020;26:70–2 https://doi.org/10.12809/hkmj187759