Delayed complications of radiotherapy treatment for nasopharyngeal carcinoma: imaging findings

Disparate Radiation-Induced Microstructural Injuries in Whole-Brain White Matter of Patients With Nasopharyngeal Carcinoma: A Longitudinal Study Using Multishell Diffusion MRI

BACKGROUND

Evidence for prevention strategies of radiotherapy (RT)-related injury in patients with nasopharyngeal carcinoma (NPC) was lacking. Understanding the dynamic alterations in the cerebral white matter (WM) microstructure after RT may be helpful.

PURPOSE

To investigate the dynamic alterations in the whole brain WM microstructure in patients with NPC in the 12 months after RT using multishell diffusion MRI (MS-dMRI).

STUDY TYPE

Single-center longitudinal study.

POPULATION

A total of 28 treatment-naïve patients with pathologically confirmed NPC (age: 39.68 ± 8.93 years, 11 female) and 20 healthy controls (age: 40.65 ± 9.76 years, 7 female).

FIELD STRENGTH/SEQUENCES

A 3 T, MS-dMRI using a single-shot echo planar imaging sequence.

ASSESSMENT

MS-dMRI was acquired at baseline for the NPC patients and healthy controls, at 0-3 (acute, AC), 6 (early delayed, ED) and 12 months (late delayed, LD) after RT for the NPC patients. The mean and maximum radiation doses to the temporal lobe were acquired. The quality of images was reviewed. MS-dMRI was analyzed using tract-based spatial statistics (TBSS). The presentations of injury were defined by the findings of TBSS.

STATISTICAL TESTS

Chi-square, t tests, repeated ANOVA, and Spearman-rank correlation analysis were used. P < 0.05 was considered to be statistically significant.

RESULTS

TBSS showed two WM injuries (injuries 1 and 2). Injury 1 emerged in the ED phase in the bilateral temporal poles and persisted throughout the ED and LD phases. Injury 2 developed from the AC to ED phase in the bilateral hemisphere and partially recovered in the LD phase. In the ED and LD phases, the multiple diffusion metrics were well correlated (r > 0.5 or <-0.5) with the RT dose, especially in the WM tracts in the temporal lobes.

DATA CONCLUSION

Disparate WM injuries were observed in NPC patients after RT. The injuries may be primarily or secondarily induced by radiation. Injury 1 may be irreversible, while injury 2 seems to partially recover.

EVIDENCE LEVEL

2.

TECHNICAL EFFICACY

Stage 4.

The risk of second primary cancer after nasopharyngeal cancer: a systematic review

PURPOSE

Second primary cancers (SPCs) after nasopharyngeal cancer (NPC) are rare, but have an impact on the follow-up of this patient population. The aim of this study is to systematically review the literature to determine the prevalence and most typical sites of SPCs after NPC.

METHODS

We searched the databases of PubMed, Web of Science, and Scopus for articles on SPCs after NPC. The Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines were followed.

RESULTS

This review includes data on 89 168 patients with NPC from 21 articles. The mean occurrence for SPCs was 6.6% and varied from 4.9% in endemic areas to 8.7% in non-endemic areas. The most frequent locations of SPCs were oral cavity, pharynx, nose and paranasal sinuses, esophagus and lung.

CONCLUSION

There is an increased risk for a SPC after NPC management, especially in non-endemic areas. However, their mean rate is lower than after other head and neck carcinomas.

MR Imaging of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma is endemic in parts of the world such as southern China and Southeast Asia. It is predominantly an undifferentiated carcinoma with a strong genetic basis and a close association with the Epstein-Barr virus. The ability of MR imaging to depict the boundaries of the primary tumor and its relationship with the complex structures of the skull base makes it the technique of choice for imaging of this disease in the head and neck. This article describes the MR imaging findings pertinent to staging and management and a new role of MR imaging in early cancer detection, in addition to a brief discussion of differential diagnoses.

The evolution of bone marrow signal changes at the skull base in nasopharyngeal carcinoma patients treated with radiation therapy

BACKGROUND

Clival infiltration is frequently seen in nasopharyngeal carcinoma (NPC) and the resultant bone marrow signal changes (BMSC) can persist even after complete tumor response to the radiation therapy (RT). The differentiation of those residual BMSC from recurrent/persistent disease may be challenging. We performed serial analysis of the clival BMSC after RT, to define an expected temporal evolution of those signal changes during the follow-up.

MATERIALS AND METHODS

Serial MRI studies of 50 NPC patients (with or without initial clival infiltration) who had undergone RT were retrospectively examined. Abnormal clival BMSC and contrast enhancement (CE) were evaluated on each follow-up scan. Duration of BMSC/CE was correlated with the degree of baseline clival involvement (BCID), RT dose, and primary mass volume (PMV).

RESULTS

Clival BMSC persisted without any evidence of recurrence, for a mean of 66.5 (max. 137) months (with accompanying CE for up to 125 months) in 26 patients with clival infiltration at diagnosis. Duration of BMSC and CE showed statistical correlations with PMW (p < 0.05), but not with RT dose or BCID. The rate of recurrence in clivus was 14%. New clival lesions that occurred within the first 12 months after RT (in six patients) did not develop recurrence suggesting radiation osteitis (12%).

CONCLUSION

After RT, residual clival medullary signal change/enhancement is seen in most NPC patients and can persist even years without recurrence.

Osteoradionecrosis of the skull base

Radiation therapy (RT) is often necessary for the treatment of head and neck cancers. Osteoradionecrosis (ORN) is a rare, but potentially serious complication of RT. RT leads to the destruction of vasculature in radiated tissue causing hypoxia and tissue necrosis. ORN can occur in any bone, but bones with naturally poor blood supply appear to be more susceptible. Bones of the skull base are susceptible, with ORN occurring in the anterior, central, and lateral skull base. Risk factors include cancer type and location, radiation dose, and a variety of patient factors. Patients often present with pain, bleeding, and foul odor and are typically found to have exposed and necrotic bone. Treatment options vary depending on the severity, but typically include pentoxifylline and vitamin E as well as surgical debridement, with less evidence supporting hyperbaric oxygen therapy. Recognition and prompt treatment of ORN will allow for improved patient outcomes.

Development of cystic malacia after high-dose cranial irradiation of pediatric CNS tumors in long-term follow-up

PURPOSE

The purpose of this study is to investigate the incidence of cystic malacia in long-term survivors of pediatric brain tumors treated with high-dose cranial irradiation.

MATERIALS AND METHODS

Between 1997 and 2015, we treated 41 pediatric patients (26 males, 15 females; age ranging from 3.3 to 15.7 years, median 9-year-old) of pediatric brain tumors [17 medulloblastomas, 7 primitive neuroectodermal tumors (PNET), 3 pineoblastomas, 6 non-germinomatous germ cell tumors (NGGCT), 8 gliomas (including 4 ependymomas, 1 anaplastic astrocytoma, 1 oligodendroglioma, 1 pilocytic astrocytoma, 1 astroblastoma)] with high-dose craniospinal irradiation. Follow-up ranged from 14.0 to 189.2 months (median 86.0 months, mean 81.5 months), the irradiation dose to the whole neural axis ranged from 18 to 41.4 Gy, and the total local dose from 43.2 to 60.4 Gy. All patients underwent follow-up magnetic resonance imaging (MRI) studies at least once a year. Diagnosis of cystic malacia was based solely on MRI findings. Of the 41 patients, 31 were censored during their follow-up due to recurrence of the primary disease (n = 5), detection of secondary leukemia after development of cystic malacia (n = 1), or the absence of cystic malacia on the last follow-up MRI study (n = 25). We also evaluated the development of post-irradiation cavernous angioma and white matter changes.

RESULTS

Following irradiation treatment, 11 patients developed 19 cystic malacia during a median course of 30.8 months (range 14.9 to 59.3 months). The site of predilection for cystic malacia was white matter around trigone of lateral ventricles with an incidence of 47.4% (9 of 19 lesions, 7 in 11 patients). Patients with supratentorial tumors developed cystic malacia statistically earlier than the patients with infratentorial tumors (P = 0.0178, log-rank test). Among the same patient group, incidence of post-irradiation cavernous angioma increased progressively, while the incidence of post-irradiation cystic malacia did not increase after 5 years. White matter degeneration developed earlier than cystic malacia or cavernous angioma, and these three clinical entities developed mutually exclusive of each other.

CONCLUSION

We attribute the higher incidence of post-irradiation cystic malacia, in our long-term follow-up study, to the cranial irradiation for pediatric brain tumors, particularly supratentorial brain tumors, and recommend a regular, long-term follow-up of brain tumor patients treated with cranial irradiation.

Radiation-induced functional connectivity alterations in nasopharyngeal carcinoma patients with radiotherapy

The study aims to investigate the radiation-induced brain functional alterations in nasopharyngeal carcinoma (NPC) patients who received radiotherapy (RT) using functional magnetic resonance imaging (fMRI) and statistic scale.The fMRI data of 35 NPC patients with RT and 24 demographically matched untreated NPC patients were acquired. Montreal Cognitive Assessment (MoCA) was also measured to evaluate their global cognition performance. Multivariate pattern analysis was performed to find the significantly altered functional connections between these 2 groups, while the linear correlation level was detected between the altered functional connections and the MoCA scores.Forty-five notably altered functional connections were found, which were mainly located between 3 brain networks, the cerebellum, sensorimotor, and cingulo-opercular. With strictly false discovery rate correction, 5 altered functional connections were shown to have significant linear correlations with the MoCA scores, that is, the connections between the vermis and hippocampus, cerebellum lobule VI and dorsolateral prefrontal cortex, precuneus and dorsal frontal cortex, cuneus and middle occipital lobe, and insula and cuneus. Besides, the connectivity between the vermis and hippocampus was also significantly correlated with the attention score, 1 of the 7 subscores of the MoCA.The present study provides new insights into the radiation-induced functional connectivity impairments in NPC patients. The results showed that the RT may induce the cognitive impairments, especially the attention alterations. The 45 altered functional connections, especially the 5 altered functional connections that were significantly correlated to the MoCA scores, may serve as the potential biomarkers of the RT-induced brain functional impairments and provide valuable targets for further functional recovery treatment.

Epidemiological characteristics of a Spanish cohort of patients diagnosed with squamous cell carcinoma of head and neck: distribution of risk factors by tumor location

PURPOSE

Head and neck cancer is a highly heterogeneous disease comprising a large number of tumors located in the cervicofacial area. This study aimed to determine the epidemiological characteristics of squamous-cell carcinomas of the head and neck in the Spanish population, and the distribution of risk factors based on tumor locations.

METHODS/PATIENTS

A cohort of 459 patients (75 oral cavity, 167 oro-/hypopharyngeal and 217 laryngeal cancers) recruited in 19 hospitals participating in the Spanish head and neck cancer cooperative group were included over 3 years (2012-2014). Epidemiological parameters and risk factors were obtained from a self-administered questionnaire, and tumor characteristics were obtained from clinical records. Multivariate multinomial logistic regression was used to assess factors associated with tumor location.

RESULTS

Most patients were males (88.4 %), smokers (95 %) and drinkers (76.5 %). Relative to laryngeal cancer, pharyngeal cancer and oral cancer were more common in women than men (OR 3.58, p = 0.003 and 4.33, p = 0.001, respectively); pharyngeal cancer was more associated with rural environment (OR 1.81, p = 0.007) and weekly alcohol intake (10-140 g: OR 2.53, p = 0.012; 141-280 g: OR 2.47, p = 0.023; >280 g: OR 3.20, p = 0.001) and less associated with pack-years of smoking (21-40 packs: OR 0.46, p = 0.045; 41-70 packs: OR 0.43, p = 0.023; ≥71 packs: OR 3.20, p = 0.015).

CONCLUSIONS

The distribution of these tumors differs between the sexes, with a higher proportion of oral cavity and pharyngeal tumors in women than in men. Oro-/hypopharyngeal cancers were more strongly associated with rural areas and with alcohol consumption, although less strongly associated with smoking than laryngeal tumors.

Nasopharyngeal granulomatous mass after radiotherapy for nasopharyngeal carcinoma

OBJECTIVE

To evaluate the diagnosis, management and nasal endoscopic surgical outcome of nasopharyngeal granulomatous mass in post-radiation nasopharyngeal carcinoma (NPC) patients.

MATERIALS AND METHODS

A total of 23 cases of granulomatous mass after radiotherapy for NPC from 2008 to 2013 treated with nasal endoscopic surgery were retrospectively reviewed.

RESULTS

Radiotherapy dose (p=0.036) and chemotherapy (p<0.001) correlated with the latency period after the treatment against NPC. The symptoms of the 23 patients before the treatment were nonspecific including nasal obstruction, purulent discharge, headache, epistaxis, foreign body sensation and/or hearing impairment. 12 patients (52.2%) were misdiagnosed to be recurrence of NPC by imaging examination (CT/MRI). After the endoscopic surgery treatment, 18 patients were disease free while the other 5 patients had developed a recurrence. Four of those five recurrent patients were cured with the repeated treatment. Histologic findings of granulation tissue with fibrin and inflammatory cells were found in all of the patients.

CONCLUSIONS

In situ granulomatous masses in post-radiation NPC patients are very prone to be misdiagnosed as recurrence of nasopharyngeal carcinoma. Chemotherapy is a significant independent factor affecting latency period (p=0.029). The nasal endoscopic surgery is an effective therapy for post-radiation nasopharyngeal granuloma; surgery can not only alleviate symptoms, what is more important, but it also helps to confirm the diagnosis.

Effects of radiotherapy on nasopharyngeal carcinoma cell invasiveness

Radiotherapy is widely used in the treatment of nasopharyngeal carcinoma (NPC), whereas its effects on the NPC growth, survival, and metastases have not been completely evaluated. Here, we compared the detected metastatic NPC tissues after radiotherapy (m-NPC) to the resected primary NPC tissues prior to radiotherapy (p-NPC). We detected higher levels of Snail2 protein, but not mRNA in m-NPC, compared to p-NPC. In vitro, a modest irradiation on NPC cells resulted in significant cell death, but increased Snail2 protein, but mRNA levels in the surviving NPC cells. Bioinformatics analyses showed that miR-613, which was significantly decreased in NPC cells after irradiation, targeted the 3'-UTR of Snail2 mRNA to inhibit its translation. Moreover, miR-613 overexpression inhibited Snail2-mediated cell invasiveness, while miR-613 depletion increased Snail2-mediated cell invasiveness in NPC cells. Finally, we detected significantly lower levels of miR-613 in m-NPC, compared to p-NPC. Together our data suggest that although radiotherapy induced NPC cell death, it may increase Snail2-mediated NPC cell invasiveness through downregulating miR-613.

Pictorial Essay: Early- and Late-term Effects of Radiotherapy in Head and Neck Imaging

The purpose of this article is to illustrate the cross-sectional imaging appearance of postradiation changes and complications of radiotherapy in the head and neck. Radiotherapy is an important treatment modality for head and neck cancer, and is often used in conjunction with chemotherapy. Recognition of the varied effects of radiotherapy to the head and neck region is essential to correctly interpret posttreatment imaging and may help prevent further complication.

MRI and CT of nasopharyngeal carcinoma

OBJECTIVE

This article reviews the MRI and CT of nasopharyngeal carcinoma. Extension of nasopharyngeal tumors, especially into the skull base and the deep facial spaces, is well illustrated on imaging. Assessment of retropharyngeal and cervical lymphadenopathy is important for treatment planning. MRI is commonly used for monitoring patients after therapy.

CONCLUSION

Imaging can detect effect of radiation on surrounding structures. The imaging findings that help to differentiate nasopharyngeal carcinoma from simulating lesions are discussed.

Sonographic appearance of parotid glands in patients treated with intensity-modulated radiotherapy or conventional radiotherapy for nasopharyngeal carcinoma

This study aimed to investigate and compare the sonographic appearances of parotid glands in nasopharyngeal carcinoma patients treated with conventional radiotherapy (RT) or intensity-modulated radiotherapy (IMRT), and to compare them with healthy subjects. Totally 43 patients treated with conventional RT, 38 patients treated with IMRT and 58 healthy subjects were recruited and underwent parotid ultrasonography. Parotid glands were assessed for their size, echogenicity and internal architectures. The mean transverse dimension of parotid glands in patients treated with conventional RT and those treated with IMRT were significantly smaller than that in healthy subjects (p < 0.05). Parotid glands of the IMRT group tended to be hyperechoic (93%), homogenous (62%), without hypoechoic areas (64%) and with marginally-seen intra-parotid ducts (89%), which are similar to those in healthy subjects. Parotid glands in the conventional RT group tended to be hypoechoic (51%), heterogeneous (98%), with hypoechoic areas (94%) and had obviously-seen intra-parotid ducts (64%). For accurate diagnosis, post-RT changes of parotid glands should be noted in ultrasound examination of patients with previous radiotherapy.

Post-treatment imaging appearances in head and neck cancer patients

Surgery and radiotherapy (with or without chemotherapy) for head and neck cancer can create a daunting array of radiological appearances post-treatment. The role of the radiologist lies not only in detecting recurrent neoplastic disease, but also identifying non-neoplastic changes that may account for clinical presentation and symptoms in this patient group. There are a number of non-neoplastic as well as neoplastic changes and disease entities that can present on surveillance imaging, such as primary resection and reconstructive surgical change, surgical neck dissection changes, radionecrosis, post-treatment denervation change, and radiotherapy-related secondary tumours. Some of these require conservative management, while others require more active treatment. Awareness and recognition of the imaging appearances of these post-treatment changes is therefore critical for the radiologist involved in the multidisciplinary care of the head and neck cancer patient.

The postradiation neck: evaluating response to treatment and recognizing complications

OBJECTIVE

We summarize the rationale for and physiology of radiation therapy for the treatment of head and neck cancer and review the imaging findings of expected changes and complications after radiation to the neck. It is important to be able to recognize these features at all stages during management of patients with squamous cell carcinoma and other head and neck malignancies and to be able to distinguish these changes from residual or recurrent disease.

CONCLUSION

Radiation therapy results in imaging findings of tissue edema followed by fibrosis, scarring, and atrophy. Complications from radiation therapy can occur months to years after treatment. Findings of a new mass, lymphadenopathy, or bone or cartilage destruction must be viewed as concerning for recurrent disease.

[Late neurotoxicity after nasopharyngeal carcinoma treatment]

PURPOSE

A retrospective analysis of risk factors for late neurological toxicity after nasopharyngeal carcinoma radiotherapy.

PATIENTS AND METHODS

Between 1993 and 2004, 239 patients with non metastatic nasopharyngeal carcinoma were treated by radiotherapy associated or not to chemotherapy. Radiotherapy was delivered with two modalities: hyperfractionated for 82 patients and conventional fractionation for 157 patients. We evaluated the impact of tumour stage, age, gender, radiotherapy schedule and chemotherapy on neurological toxicity.

RESULTS

After a mean follow-up of 107 months (35-176 months), 21 patients (8.8%) developed neurological complications, such as temporal necrosis in nine cases, brain stem necrosis in five cases, optics nerve atrophy in two cases and myelitis in one case. Five- and ten-year free of toxicity survival was 95 and 84% respectively. Young patients had greater risk of temporal necrosis, and hyperfractionated radiotherapy was associated with a significantly higher risk of neurological complications (14.6% vs 5.7%, p=0.02). On multivariate analysis, hyperfractionation and age were insignificant.

CONCLUSION

Late neurological toxicity after radiotherapy for nasopharyngeal carcinoma was rare. Younger age and hyperfractionation were considered as risk factors of neurological toxicity in our study.

Osteoradionecrosis of the cervical spine complicated by pneumocephalus and meningitis in a nasopharyngeal cancer patient radically treated with radiotherapy 11 years ago

Superimposed infection of osteoradionecrotic cervical spine with cranial extension is difficult to treat and potentially fatal. This report describes the case of a middle-aged Chinese man 11 years post radical radiotherapy for nasopharyngeal cancer with no evidence of disease presenting initially with neck pain secondary to cervical osteoradionecrosis. He was re-admitted a month later with aspiration pneumonia associated with Streptococcus milleri bacteraemia, complicated by septic shock. The last re-admission was 2 months later with fever, expressive dysphasia and right upper motor neuron signs. There was interval increase of dental and peridental soft tissue mass, interval widening of atlantodental distance on MRI cervical spine associated with pneumocephalus, meningeal enhancement and pre-pontine soft tissue mass on CT brain consistent with infected osteoradionecrotic cervical spine complicated by cranial extension. The patient also had concomitant bilateral pneumonia and subsequently passed away from fulminant sepsis.

[Nasopharyngeal carcinoma]

Nasopharyngeal carcinoma is relatively common. Undifferentiated Carcinomas of Nasopharyngeal Type (UNCT) are endemic Epstein-Barr virus (EBV)-related tumors. They are mainly radiosensitive. The role of imaging is to assess locoregional extension, TNM classification and adjust the radiation fields. MRI is essential to determine the initial extension. CT is useful to confirm the presence of bone involvement and evaluate nodal status. MRI and CT are necessary for the post-treatment follow-up.

Case-control study and meta-analysis of SULT1A1 Arg213His polymorphism for gene, ethnicity and environment interaction for cancer risk

Cytosolic sulphotransferase SULT1A1 plays a dual role in the activation of some carcinogens and inactivation of others. A functional polymorphism leading to Arg²¹³His substitution (SULT1A1*2) affects its catalytic activity and thermostability. To study the association of SULT1A1*2 polymorphism with tobacco-related cancers (TRCs), a case–control study comprising 132 patients with multiple primary neoplasm (MPN) involving TRC and 198 cancer-free controls was carried out. One hundred and thirteen MPN patients had at least one cancer in upper aerodigestive tract including lung (UADT-MPN). SULT1A1*2 showed significant risk association with UADT-MPN (odds ratio (OR)=5.50, 95% confidence interval (CI): 1.09, 27.7). Meta-analysis was conducted combining the data with 34 published studies that included 11 962 cancer cases and 14 673 controls in diverse cancers. The SULT1A1*2 revealed contrasting risk association for UADT cancers (OR=1.62, 95% CI: 1.12, 2.34) and genitourinary cancers (OR=0.73, 95% CI: 0.58, 0.92). Furthermore, although SULT1A1*2 conferred significant increased risk of breast cancer to Asian women (OR=1.91, 95% CI: 1.08, 3.40), it did not confer increased risk to Caucasian women (OR=0.92, 95% CI: 0.71, 1.18). Thus risk for different cancers in distinct ethnic groups could be modulated by interaction between genetic variants and different endogenous and exogenous carcinogens.

Nasopharyngeal carcinoma: our experience

The objectives of our study were to characterize nasopharyngeal carcinoma patients in the Portuguese Institute of Oncology Hospital in Lisbon (IPOLFG) and identify the main factors that interfere with patients survival rate. We performed a retrospective study involving 157 patients (65% male and 35% female) between the years 2000 and 2005, and a histological classification according to Health World Organization. We constructed a Kaplan-Meier survival curve for the studied patients and evaluated the significance of the different studied factors with a Pearson correlation study. With an average age of 53 years, most of the carcinomas were type III (58%), followed by type II (30%) and at last type I (8%). Fifty-one of carcinomas were in stage IV at time of diagnosis. Ninety-five patients (60%) had remission. Five-year actuarial survival rate of all patients was 65.1%. There was a significant difference (P = 0.033) in the actuarial survival rate of staged IV patients treated with adjuvant chemotherapy. Undifferentiated nasopharyngeal carcinoma is the most frequent type in our geographic area. Chemotherapy improves survival rate, mainly in late stages.

MR imaging of nonmalignant polyps and masses of the nasopharynx and sphenoid sinus after radiotherapy for nasopharyngeal carcinoma

BACKGROUND AND PURPOSE

The development of a new polyp or mass in the radiation field of a previously treated carcinoma is usually an ominous sign of a recurrent cancer, but rarely may it be caused instead by a nonmalignant process. The purpose of this study was to document the MR appearance of unusual nonmalignant polyps or masses (NMPMs) in the nasopharynx and sphenoid sinus arising after radiation treatment of nasopharyngeal carcinoma.

MATERIALS AND METHODS

The MR imaging reports of patients undergoing imaging after radiation therapy for nasopharyngeal carcinoma were reviewed retrospectively to identify patients with unusual polyps and masses in the nasopharynx. The MR images of those patients with no evidence of malignancy on biopsy or follow-up were reviewed.

RESULTS

The MR imaging reports of 1282 patients were reviewed, and 11 patients (1%) with NMPMs in the nasopharynx or sphenoid sinus were identified. Two patterns were identified: contrast enhancing nasopharyngeal polyps ranging in size from 1 to 5 cm (n = 5) and sphenoid sinus masses consisting of a nonenhancing mass filling a nonexpanded sinus (n = 4) and a heterogeneous enhancing mass expanding the sinus (n = 2). Osteoradionecrosis produced a large defect in the roof of the nasopharynx causing direct communication with the sphenoid sinus (n = 6). Histology revealed granulation tissue in all of the patients with variable amounts of fibrin and inflammatory cells. A direct infective etiology was not proved in any patient.

CONCLUSION

NMPMs in the nasopharynx and sphenoid sinus are rare complications after radiation therapy to the skull base, but the radiologist needs to be aware of their appearance so that they can be considered in the differential diagnosis of suspected tumor recurrence.

Nasopharyngeal carcinoma: the role of magnetic resonance imaging in diagnosis, staging, treatment, and follow-up

Nasopharyngeal carcinoma (NPC) is a distinct entity from pharyngeal squamous cell carcinoma (SCCa). Nasopharyngeal carcinoma has a unique histological appearance; has different inciting factors to SCCa; and has unique familial, genetic, and geographic predispositions. Nasopharyngeal carcinoma also has a different pathological behavior to pharyngeal SCCa, with a tendency for clival invasion, intracranial spread, and early systemic metastasis. In keeping with this distinct pathological behavior, NPC has particular imaging manifestations and staging criteria that differ significantly from pharyngeal SCCa. These features are typically much better evaluated with magnetic resonance imaging than with computed tomography. This article presents the current clinical and epidemiological background of NPC with specific reference to the role of magnetic resonance imaging in all stages of patient management, from diagnosis and staging of NPC to the role of the radiologist in treatment planning and follow-up imaging evaluation.