In patients with breast cancer, the appearance of sclerotic bone lesions on imaging should raise the suspicion of skeletal metastases. However, before making the diagnosis it is important to consider the clinical context and remember that there are conditions that can mimic bone metastasis. We present two cases of mimics of bone metastasis: systemic mastocytosis and osteopoikilosis. These cases demonstrate clinical and radiological characteristics that would make a diagnosis of bone metastasis less likely, and highlight the need for an awareness of mimics of bone metastasis.