Skeletal muscle metastases: pitfalls and challenges of a highly inhospitable environment

Although skeletal muscle represents approximately 50% of body weight and is one of the largest organs of the human body, skeletal muscle metastases (SMM) from solid organ malignancy are relatively rare, with a prevalence ranging from 0.03% to 16% in autopsy studies. Therefore, knowledge on this topic is scattered and derives mainly from case reports or, at best, small case series, with the exception of one systematic review of the Literature. The aim of this commentary is to underline the main features of this type of metastases, the rarity of which can delay a correct diagnosis.