Ortho Dx: Golf-ball-sized subcutaneous mass on the knee

A 69-year-old man presents with a painful mass on the anterior aspect of his right knee. The mass has grown from a pimple-sized lesion to a mass the size of a golf ball over the last 3 weeks. The patient has a history of stage-4 lung cancer, coronary artery disease, and gastroesophageal reflux disease. The patient is being ...