[Lung metastasis disclosing a calf tumor].

Lung metastasis is a common finding, either before, with or after discovery of the primary tumor. Histological examination of a lung formation of unknown origin can lead to diagnosis of a primary tumor. We report the case of a 28-year old woman who presented an apparently primary tumor in the lower left pulmonary lobe. Pathology reported soft tissue alveolar sarcoma. The first manifestation of this rare soft tissue tumor can be a lung or brain tumor. Imaging evidenced the primary tumor in the left calf. Histology confirmed the diagnosis and the metastatic nature of the lung tumor.