Benign incidental do-not-touch bone lesions

Benign bone lesions may occasionally be incidentally detected on radiographs and are also increasingly found on CT or MRI performed for other clinical indications. Although mostly asymptomatic or associated with minor symptoms, these lesions may simulate true pathological lesions, causing problems in diagnosis. For instance, asymptomatic benign bone lesions can be misinterpreted as metastasis when incidentally encountered in a patient with known cancer. Recognising these entities as "do-not-touch" lesions helps avoid unnecessary further investigation or harmful intervention. In this review, we highlight three groups of bone incidentalomas found in adults, namely: osteolytic lesions, osteoblastic lesions, and bone protuberances. We aim to review the key imaging features of selected common and less common conditions in these three groups, so as to help radiologists confidently identify these benign do-not-touch lesions and to distinguish them from more sinister pathological lesions.