Diagnosis

Diagnosing an MFS can be a challenge. The initial growth often represents just part of the underlying tumor, which may have spread extensively around the base of the growth and down into deeper tissue. Even with advanced imaging, it can be difficult to accurately assess the true extent of the cancer.

Signs that a growth on a leg or arm may be an MFS or a similar cancer include:

• Being golf ball-sized or larger
• Getting larger over time
• Lying deep in muscle instead of just under the skin

Tests to assess a suspicious-looking growth that may be an MFS include:

• Magnetic resonance imaging.
• Core needle biopsy

If these tests find an MFS or another type of soft tissue sarcoma, a chest X-ray is typically the next step. Its purpose is to determine whether the cancer has spread (metastasized) to your lungs, the most likely site for MFS metastasis.