Cooper is a right-handed 14-year-old who presents with a lump on the right upper arm.

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<p>Cooper is a right-handed 14-year-old who presents with a lump on the right upper arm.</p><p>This has been present for many years, is painless and does not seem to be enlarging.</p><p>In recent months, he has started playing basketball and has noticed some restriction of right shoulder movement when making passes and taking shots.</p><p>He is also self-conscious wearing his basketball uniform. He is systemically well with no other history of note.</p><p>On examination, there is a large, hard, non-tender mass at the posterolateral proximal humerus, and shoulder range is globally slightly restricted. A shoulder X-ray is requested.</p>

Dr Kate Kelso is a GP and medical editor at Australian Doctor.