Metastatic spindle cell sarcoma: A rare type of undifferentiated soft tissue neoplasm

Sarcomas are rare and characterised by an incidence of approximately 5 cases/100.000 people. Primary spindle cell sarcomas are a subclassification of soft tissue sarcomas, known as uncertain differentiation tumours, based on their unspecific line of differentiation. It might begin in layers of connective tissue under the skin, between muscles or surrounding organs. Diagnosis can be challenging and delayed due to the often-painless nature of these cancers and the common assumption of an underlying benign condition. The presence of distant metastatic disease at the time of the initial diagnosis is not frequent, but is more likely in large, deep and high-grade malignancy sarcomas. Our case describes an elderly patient diagnosed with an asymptomatic undifferentiated spindle cell sarcoma in the lower limb that developed metastatic disease after intentional curative therapy.