The question is not classic: which signs suggest a possible malignancy when faced with a solitary bone lesion? Usually radiologists try to identify the leave me alone lesions, for which nothing is needed. Here we consider the suspicious lesions. Clinical and radiological indicators are proposed, leading to a probability. Nowadays, a biopsy is nevertheless always requested before treating a malignant lesion, even if suspicion is very high. But histology should integrate with the radiological signs.