Clinical features and dosimetric evaluation of carbon ion radiation-induced osteoradionecrosis of mandible in head and neck tumors.

BACKGROUND AND PURPOSE: Osteoradionecrosis (ORN) affects the patient's quality of life by making eating and maintaining oral hygiene painful. This study aimed to analyze carbon ion radiotherapy (C-ion RT)-induced ORN of the mandible. MATERIALS AND METHODS: A retrospective study of 199 patients with head and neck tumors treated with C-ion RT was performed from 2010 to 2019. Only 11 patients with tumors located in the oropharynx and floor of the mouth were analyzed. C-ion RT consisted of 57.6 Gy or 64.0 Gy (relative biological effectiveness) in 16 fractions. The mandible was analyzed for magnetic resonance imaging (MRI) changes and bone exposure. The relationship between the radiation dose and ORN of the mandible was analyzed. RESULTS: Five patients (45.5%) had ORN of the mandible. The median follow-up time was 68 months. The median onset times based on MRI changes and bone exposure were 9 and 15 months, respectively. Doses of 30 Gy (relative biological effectiveness) to the mandible and teeth showed the most significant effect, causing ORN at 29.5 ± 6.7 cc and 3.9 ± 1.8 cc, respectively, with cut-off values at 16.5 cc (p = 0.002) and 1.8 cc (p = 0.0059), respectively. CONCLUSION: This is the first study reporting the incidence, onset time, and risk-predictive dosimetry parameters of C-ion RT-induced ORN of the mandible. Our study will be useful for establishing clinical strategies for C-ion RT to the head and neck near the mandible.

Intraosseous epidermoid cyst of the distal phalanx reconstructed with synthetic bone graft.

Intraosseous epidermoid cysts are exceedingly rare. Known as pseudotumors, not true neoplasms, intraosseous epidermoid cysts usually involve the phalanges, the skull, and the toes. Intraosseous epidermoid cysts typically present as destructive osteolytic lesions on X-ray, mimicking malignant bone tumors. Here, we present two cases of an intraosseous epidermoid cyst in the distal phalanx treated with curettage and synthetic bone graft, followed by a review of the relevant literature. In both cases, the patient presented with a painful enlargement of the fingertip following a minor trauma. Magnetic resonance imaging demonstrated lesions involving the distal phalanx that had a low signal on T1-weighted imaging (WI) and a high intensity on T2-WI. In both cases, the lesions were not enhanced by gadolinium. Good remodeling and functional recoveries were obtained. For physically active patients with substantial bone defects, synthetic bone graft may be recommended.

Classification of odontoid destruction in patients with rheumatoid arthritis using reconstructed computed tomography: reference to vertical migration.

OBJECTIVE: To reveal the factors that determine the natural course of subluxation of occipital-cervical lesions in rheumatoid arthritis (RA). The atlanto-axial region is one of the most common locations for lesions in RA. Some cases progress from reducible atlanto-axial subluxation (AAS) to irreducible vertical migration, while others continue to exhibit reducible AAS. No study has revealed the factors that determine the natural course of subluxation. We focus on the odontoid as a key structure of the progression of occipito-cervical lesions and investigated this region in patients with RA using reconstructive computed tomography (CT) images, and analyzed factors in association with CT findings. METHODS: Fifty-eight patients with RA and 40 age-matched controls, all women, were studied. Associated factors, including C-reactive protein, erythrocyte sedimentation rate, steroid usage, and the severity of local osteoporosis, were analyzed as measurements in association with odontoid destruction. RESULTS: The destruction of odontoid and atlanto-odontoid joint were common in patients with RA. The more destruction observed in the odontoid process, the greater is the degree of progression of vertical migration. Local osteoporosis is a significant factor in odontoid destruction, based on a cortico-cancellous index of 42% in cases of grade III odontoid destruction. CONCLUSION: The odontoid process is a key structure in the progression of occipito-cervical lesions in patients with RA.