Good evening sir,
It looks like your mother is suffering from spindle cell neoplasm . It is a subtype of soft tissue sarcoma. In simple terms it is a malignancy which arises from muscle tissue. But don’t worry it is treatable. Our next step would be to confirm that the disease is localised. We would have to do CT CHEST to rule out lung mets. Then if the disease is confined to local site , surgery( wide local excision) would be preferred after which your mother has to go through Radiation therapy to prevent further recurrence. Radiation therapy significantly reduces the risk of local recurrence and improves the overall survival in spindle cell neoplasm
Next Steps
To undergo wide local excision of the swelling followed by Radiation