Fibromatosis is an extremely rare tumor that arises from the myofascial tissue and has high rates of infiltration and recurrence. Fibromatosis of the chest wall is even less common, and wide surgical resection is the preferred treatment alternative to radiation therapy, chemotherapy, and systemic treatments. We report the case of a 3-year-old boy with radiologically and pathologically confirmed fibromatosis of the periscapular region who underwent wide resection. We discuss diagnosis, treatment options, and technical pearls for a desmoid tumor of the chest wall. The resection should go through healthy tissue because of the infiltrative nature of the tumor. Although visceral involvement did not occur in this case, surgeons should be aware of its possibility, and surgery should be performed by a multidisciplinary team, including a pediatric orthopedic surgeon, a thoracic surgeon, and an anesthesiologist. [Orthopedics. 2022;45(5):e276-e279.].