A 51-year-old woman was found to have a new 14 × 6 mm soft tissue mass under the right serratus muscle on a CT scan of the chest performed for routine surveillance due to her history of stage I lung cancer. A follow-up CT scan performed 4 months later showed that the mass had increased in size to 22 × 8 mm. The patient presents to the oncology clinic to discuss the results of the CT scan. She has no pain or swelling on the right lateral chest and no cough, fever, or shortness of breath. She is at her baseline health with good appetite and functional status.