According to the previous case studies, nine PIOCs have been reported in pediatric populations [12-20]. A summary of all 10 pediatric cases, including this case, is provided in Table 1 and 2. PIOC is more common in adult males [3,5-11]; however, seven of the total 10 pediatric cases were female. PIOC occurs more often in the mandible than maxilla [3,5-11], seen in seven of the pediatric patients. The most common symptom was swelling, followed by pain [3,5,7]. The symptoms of the pediatric patients were consistent.
PIOC can be misdiagnosed as odontogenic cyst because it occasionally presents with a well-defined border in panoramic view or CT [21-24]. Differential diagnosis of PIOC from odontogenic cyst is important because the surgical approach is different. Kaffe et al. [21] reported that 61% of PIOC cases presented as a unilocular radiolucent lesion. In our review of pediatric cases, six of 10 cases showed unilocular radiolucency. Radiologic borders that were defined but non-corticated were reported to occur in 57% of the PIOC cases and the remaining 43% had diffuse borders. In cases with poorly defined borders, such as those with diffuse margins, the lesions could be unambiguously distinguished from odontogenic cyst. However, since cases with well-defined borders can be misdiagnosed as odontogenic cyst, a differential diagnosis should be thoroughly considered. According to Kaffe et al. [21], a defined but non-corticated border could be a useful feature for differential diagnosis. A well-defined but non-corticated border was observed in five of the 10 pediatric PIOC patients (Table 1). Moreover, tooth displacement and root resorption should be considered as other radiologic features as PIOC tends to grow too rapidly to produce such features [7,19,21,25]. However, four of the pediatric cases in our review showed tooth displacement and five showed root resorption. It was peculiar that these features occurred in the pediatric patients. Although tooth displacement and root resorption are features for slowly growing lesions such as odontogenic cysts, these features should be considered for differential diagnosis of PIOC in pediatric populations. As a rare finding, radiopaque foci were observed in this case and in Punnya et al.’s pediatric case [15]. Although PIOC usually presents as an osteolytic lesion, small radiopaque foci due to calcification or periosteal reaction can be observed, albeit rarely [10,26-28].
Among the 10 pediatric cases we reviewed, the initial diagnosis for five was odontogenic cyst. Huang et al. [7] reported that this diagnostic delay did not show any statistically significant prognostic difference. However, Naruse et al. [25] reported that preoperative dental procedures might be potential prognostic factors and suggested that no intervention before definitive diagnosis could achieve a better prognosis. Therefore, incisional biopsy with obtaining multiple specimens is necessary to rule out an underlying carcinoma [8,9,14,17]. Regardless of patient age, biopsy should be considered for any lesion with any of the unusual radiographic presentations mentioned above. The pediatric patient reported by Charles et al. [17] was accurately diagnosed by biopsy and had the longest follow-up period without recurrence. A biopsy was not considered for definitive diagnosis in the present case although there were atypical radiographic findings. Local recurrence occurred five months after the initial operation, that is, four months after the definitive surgery.
The primary treatment for PIOC is surgical resection [3,8,11,29]. In the present case, because simultaneous reconstruction was necessary, hand-wrist radiography was analyzed for assessment of growth potential. Her skeletal age was assessed as 15-16 years old. Previous research has concluded that the face matures between 12 and 15 years in males and two years earlier in females [30,31]. The vascularized fibular free flap is a reliable option for mandibular reconstruction, even in pediatric patients [32,33]. Therefore, the fibular free flap was employed for this 14-year-old female patient.
Recent reviews reported the rate of cervical lymph node metastasis to be 12.8% [3] and 70.1% [11]. In our case review, three of the 10 pediatric cases showed cervical metastasis. Wenguang et al. [11] reported nodal status to be a significantly poor prognostic factor for survival. However, de Morais et al. [3] reported that lymph node metastasis was not statistically associated with survival. Although these outcomes conflict, it seems reasonable that neck dissection be considered among the surgical procedures for PIOC. In the present case, there were no metastatic lymph nodes on enhanced CT or MRI. However, because there were borderline-sized lymph nodes at the right level IB, selective neck dissection was performed.
In recent literature, de Morais et al. [3] reported a local recurrence rate of 22.1% and Ye et al. [4] reported a local recurrence rate of 24.1%. In this study, local recurrence occurred in three pediatric patients, including the present case, a rate of 30% although the total cases were only 10. In one report, a four-year-old female patient suffered recurrence five months after excision and underwent additional radical excision [3]. However, 10 months later, recurrence recurred, the lesion was removed, and the area was irradiated. She was alive after one year of follow-up. In another case, a 16-year-old male patient suffered recurrence two months after excision and underwent total mandibulectomy after one month. However, he died two months after the surgery [13]. The 14-year-old female patient in the present study suffered recurrence four months after definitive surgery. She underwent CCRT for one months, but the recurred lesion did not decrease. According to de Morais et al. [3] and Ye et al. [4], local recurrence is a significant prognostic factor for survival. Likewise, pediatric PIOC cases with local recurrence showed poor prognosis. The five-year survival rate has been reported as 44.6% [3] and 53.2% [4]. However, the five-year survival rate of the pediatric patients could not be evaluated because of the rarity of the cases and relatively short follow-up periods.
Because PIOC has a poor prognosis, accurate diagnosis and adequate surgical procedures are important. Continuous updates are required to analyze the pathophysiologic mechanism of PIOC, and a recent approach such as genetic analysis [34] could contribute to understanding the pathophysiology of PIOC.