4 Discussion
We have reported the surgical and biochemical outcomes for head and neck TIO. PMT resection in the head and neck region was associated with high local recurrence/residual disease rate (56%), which was significantly higher than that of the extremities and trunk (25%). However, biochemical remission was achieved in the majority of the patients after re‑excision at the last follow-up (89%, 8 out of 9).
Most of the previous reports concerning the head and neck TIO were small case series often mixed with other sites, which had short-term follow-ups within two years after surgical excision.5-7,16,17 Pal et al. reported surgical excision in 30 cases TIO in various sites, which resulted in remission in 73% of the patients, whereas disease persistence and tumor recurrence in 18% and 9% of the cases, respectively.18 Zhu et al. analyzed 43 patients with sinonasal tumors, including PMT, odontogenic fibroma, and hemangiofibroma, which were associated with TIO.19 In the series, a high local recurrence rate or nonremission was found (12%). The other report illustrated the seven patients with TIO in the paranasal sinus, intracranial, and maxilla who underwent surgical excision.20 They demonstrated that four of seven (57%) had persistent illness after surgical removal, and three patients were managed by external beam radiation treatment for recurrent tumors. Consistent with these reports, our data demonstrated a great residual disease/local recurrence rate in the head and neck PMT. However, in most of our patients, biochemical remission was attained after re-excision without radiation treatment. We believe that re-excision of the residual/local recurrent tumor without radiation therapy is a practical treatment option. In contrast to our findings, Li et al. reported that the refractory rate was the lowest in head and neck tumors (7.5%) compared to other sites.8 However, they did not state the details of localization of the tumor, surgical methods, and complications after surgery for the head and neck tumors. In our residual/recurrent cases, craniotomy was conducted due to the proximity of the brain in three cases. The surgical process, surgical margin, and localization of the tumor presumably contributed to the differences in outcomes.
Complete surgical excision with wide margins was the cornerstone of PMT management.21,22 The main surgical challenge of resection of head and neck PMT is the difficulty of obtaining a clear margin because of the anatomical complexity and proximity of the brain or other important organs. Previous studies showed that soft tissue PMT with an irregular boundary observed on imaging tended to infiltrate into subcutaneous fat.21 Furthermore, bone PMT demonstrated invasion into cancellous and cortical bone.22 These findings suggest that in patients with these imaging features, resection of infiltrative margin in soft tissue tumor or resection of thinned cortical bone may be required to reduce the risk of local recurrence/residual disease. However, excessive removal of the surrounding tissues may increase the risk of surgical morbidity, particularly in cases of head and neck PMT. Surgeons need to balance the risk of surgical morbidity and local recurrence/residual disease.
TIO is a rare and underreported condition because treating clinicians are unaware of its characteristic, clinical, and biochemical profiles.3 Through this research, we highlighted our experience with TIO cases including the head and neck regions. A significant time gap between the initial presentation until the diagnosis existed even in the presence of severe symptoms in our series. Other challenges included the difficulty of distinguishing PMT from other incidental findings on imaging studies. Especially in the head and neck area, apical periodontitis was encountered, which was suspected to be a tumor that caused TIO (Fig. 3a–f). Furthermore, X-linked hypophosphatemic rickets/osteomalacia is one of the possible differential diagnoses in patients with osteomalacia who have abnormal findings in the alveolar bone area, which can lead to a variety of dental complications, including apical periodontitis.23 These findings will raise awareness and provide valuable insights into the treatment of issues associated with this rare disease in the head and neck region.
We would like to acknowledge the limitations of our study. First, this study involving a heterogeneous and small group of patients. Second, our study is a retrospective review and there are selection, indication, and expertise biases concerning both the initial surgery and subsequent procedures. Third, patients were treated over two decades, and we were unable to adjust for important confounders, including evolution in treatment strategies and medical/surgical/imaging management/techniques. A histopathology and radiology review at an institutional multidisciplinary board meeting, we believe, has reduced these biases.
In conclusion, PMT in the head and neck area demonstrated a high local recurrence/residual disease rate. However, biochemical remission was achieved in most patients at the last follow-up. Before definitive resection, surgeons should discuss with their patients the difficulty of obtaining clear margins due to the complex anatomy of the region and the proximity of important organs.