Neck mass secondary to pedicle ossification after oromandibular reconstruction

Abstract

Conclusions: Development of a firm neck mass after treatment of head and neck cancer often indicates recurrent tumor. Heterotopic ossification has not been previously reported as a potential etiology of neck masses after fibula free flap oromandibular reconstruction in the head and neck surgery literature. The radiographic incidence of this phenomenon is high, while the clinical incidence of neck masses secondary to heterotopic ossification is low. Heterotopic ossification can be distinguished from recurrent tumor on the basis of physical examination, radiographic assessment, and/or fine needle aspiration biopsy. Awareness of heterotopic ossification should be included in the differential diagnosis of patients with a neck mass who have undergone fibula free flap reconstructions. Review of a patient database of 520 consecutive fibula free flaps between 1995-2010 revealed sixtysix patients who had postoperative CT scans of the neck available for radiographic review. Of the 66 patients who had postoperative CT scans available for radiologic assessment, 43/66 (65%) showed heterotopic ossification of the fibula periosteum. In an effort to elucidate risk factors for heterotopic ossification, statistical analysis was used to interpret the data. There was no difference in frequency of males and females between in patients with heterotopic ossification (p = 0.4). The mean ages of patients with radiographic evidence (58.3 years) of ossification and those without radiographic evidence of ossification (63.2 years) were not shown to be significantly different with Student’s t-test (p = 0.89). There was also a significant difference (p = 0.004) between post-operative time to CT scan between patients with and without evidence of heterotopic ossification on CT scan. Similarly, a Pearson’s chisquare test was performed to compare frequency of ossification between patients with scans less than 180 days post-operatively and scans after 180 days post-operatively. Patients with scans later than 180 days post-operatively were more likely to have evidence of heterotopic ossification (p = 0.007). The fibula osteocutaneous flap is perhaps the most widely used vascularized bone flap for reconstruction of segmental mandibular defects. Once the extirpative part of the surgery is completed and the fibula flap has been elevated, the composite bone and soft tissue graft from the leg is then harvested. A subperiosteal dissection protects the pedicle and preserves the periosteal plexus (see Figure 1). The unused pieces of the fibular bone are then excised and discarded. The proximal periosteum that was dissected off of the discarded fibula is allowed to drape over the peroneal vessels.