Desmoid tumors are benign neoplasms composed of fibrous tissue arising from musculoaponeurotic structures throughout the body.1 These are rare lesions accounting for only 0.03% of all tumors. Alternate names for this tumor include grade I fibrosarcoma and aggressive fibromatosis.1 The majority of these neoplasms present in the abdomen, with only 12% to 15% presenting in the head and neck.2 Desmoid tumors require wide excision of the tissues involved. Depending on the extent of the resection and structures involved, the reconstruction can be managed by primary closure, regional flaps, or free tissue transfer.3

Patients who present with desmoid tumors in the masticator space provide a particular challenge because the surgeon must remove the tumor while preserving oral function. A common consequence of this surgery is trismus, which can arise as a result of fibrosis and scar contracture.4

The incidence of trismus in the setting of prior treatment for head and neck cancer has been quoted to range between 5% to 38% of patients.5 Primary risk factors include previous irradiation, multiple treatments with surgery and/or chemoradiation, fibrous or bony ankylosis of the temporomandibular joint, and recurrence of oral cancer. In the case of severe trismus, traditional surgical intervention may include release of scar located at the level of the mucosa or submucosa, myotomy of the pterygomasseteric sling and/or temporalis muscle, and in select advanced cases, a coronoidectomy.6

In this report, we present a unique case of severe trismus due to extensive, dense scarring and fibrosis following surgical excision of a desmoid tumor in the masticator and parapharyngeal spaces in a pediatric patient. Microvascular free tissue augmentation was undertaken to preserve the increased oral aperture that resulted following release of the trismus. Following multiple unsuccessful attempts to achieve a durable solution to this patient's condition, it was felt that the introduction of a healthy vascularized tissue barrier to prevent recurrent scar formation represented a viable treatment option. The management of desmoid tumors in the head and neck is also reviewed.