Review Question - QID 214861

A 23-year-old woman presents to her primary care physician for an abdominal mass. She denies any abdominal pain, nausea, vomiting, or change in bowel habits, and is eating and drinking well. Approximately 6 months ago, she had an abdominal mass that was surgically removed from the left anterior abdominal wall. She has no other medical history and takes no medications. Her father has a history of having "many polyps" that required prophylactic resection of his colon. Her temperature is 99°F (37.2°C), blood pressure is 120/80 mmHg, pulse is 80/min, and respirations are 16/min. On physical examination, there is a 2 x 3 cm firm oblong mass in the left anterolateral abdominal wall that is nontender to palpation. Which of the following is the most likely diagnosis?