In April 2021, a 62-year-old man was diagnosed with stage IV nasopharyngeal squamous cell carcinoma (cT4N0M0, p16-negative). Following multidisciplinary review, concurrent chemoradiotherapy was recommended, and a feeding gastrostomy was placed that month because of nasopharyngeal obstruction. Radiotherapy was planned using volumetric-modulated arc therapy (VMAT) with 6-MV photons on a planning computed tomography (CT) scan acquired with thermoplastic mask immobilisation (1–2-mm slices). Target volumes followed the institutional protocol, with expansion of the gross tumour volume (GTV) to the clinical target volume (CTV) and then to the planning target volume (PTV) using 3–5-mm isotropic margins. Two coplanar arcs with heterogeneity correction delivered 66 Gy to the nasopharyngeal primary, 59 Gy to intermediate-risk, and 54 Gy to low-risk cervical nodal volumes in 31 fractions (5 May–24 June 2021). Daily cone-beam CT (CBCT) was used for image guidance. Organs at risk — including the bilateral temporal lobes, brainstem, optic apparatus, cochleae, parotids, mandible, and spinal cord — were contoured and planned according to institutional constraints. Patient-specific dose–volume histogram metrics for organs at risk and the voxel-wise dose at the eventual lesion site could not be retrieved from the archived plan. Concurrent cisplatin was administered at 75 mg/m2 on 3 May (day 1), 100 mg/m2 on 24 May (day 22), and 75 mg/m2 on 14 June (day 43). Treatment was completed as planned and was well tolerated.
Post-treatment CT in mid-2021 showed a small residual lesion without progression, and the patient remained asymptomatic during routine imaging follow-up. Over subsequent years, he developed mild neuropathy (grade 1), persistent dysphonia, and bilateral mixed hearing loss attributed to treatment. In January 2025, a follow-up cranial CT scan (Fig. 1C, 1D and Supplementary File — Fig. S1) revealed increased vasogenic oedema in the left temporal lobe, with compression of the temporal horn but no midline shift. Heterogeneous contrast enhancement, more conspicuous in the anteroinferior temporal lobe, raised concern for an infiltrative process and potential central nervous system progression. Dexamethasone 4 mg every 8 hours for 7 days was prescribed to control the oedema.
Figure 1.
Multimodal imaging of an infiltrative lesion in the left temporal lobe. A. Perfusion magnetic resonance imaging (MRI) shows no increase in relative cerebral blood volume, suggesting the absence of neoangiogenesis. B. Axial fluid-attenuated inversion recovery (FLAIR) MRI reveals a hyperintense, lobulated lesion predominantly in the white matter. C. Computed tomography (CT) in the bone window shows skull-base osteolysis involving the clivus and sphenoid. D. Contrast-enhanced CT demonstrates a heterogeneous lesion with vasogenic oedema and mass effect
Magnetic resonance imaging (MRI) in February 2025 (Fig. 1A, 1B) demonstrated a heterogeneous infiltrative lesion in the left temporal lobe, with T2-weighted and fluid-attenuated inversion recovery (FLAIR) hyperintensity predominantly in the white matter of the temporal pole, extending to the temporal gyri and temporal stem. The lesion showed heterogeneous, partially lobulated enhancement measuring approximately 4.0 × 2.7 × 2.2 cm. Dynamic susceptibility contrast perfusion did not demonstrate increased relative cerebral blood volume within the lesion, arguing against neoangiogenesis. Susceptibility-weighted imaging showed small foci of low signal compatible with haemosiderin deposition. There was no diffusion restriction, excluding acute ischaemia. Overall, the findings favoured radiation-induced necrosis over neoplastic recurrence.
A follow-up MRI on 26 April 2025 (Supplementary File — Fig. S2) showed partial regression of the enhancing lesion, consistent with improving radionecrosis. DSC perfusion from the same examination did not demonstrate increased rCBV within the lesion, further supporting radionecrosis. A further MRI in August 2025 (Supplementary File — Fig. S3) confirmed an additional reduction in size to 3.0 × 1.4 × 1.0 cm, without increased perfusion. The nasopharyngeal region remained unchanged, with findings compatible with post-treatment effects. By September 2025, the patient was asymptomatic, with an Eastern Cooperative Oncology Group performance status of 0–1, had gained weight steadily to 75 kg, and showed no evidence of disease progression. Neither bevacizumab nor surgery was required; the patient remained under clinical and radiological surveillance.
Discussion
Nasopharyngeal squamous cell carcinoma is often diagnosed at an advanced stage, and chemoradiotherapy is the standard of care [1]. Post-treatment sequelae, such as neuropathy and hearing loss, are common. Radionecrosis is a late effect of radiotherapy related to vascular injury, blood–brain barrier disruption, and chronic inflammation, leading to oedema and tissue hypoxia [2, 3]. Its imaging appearance can mimic recurrence; therefore, multiparametric evaluation is essential. The pattern favoured radionecrosis: DSC MRI showed no increase in rCBV, diffusion-weighted imaging/apparent diffusion coefficient imaging showed no diffusion restriction, SWI revealed punctate susceptibility foci, symptoms improved after a course of dexamethasone, and serial MRI demonstrated progressive reductions in enhancement and FLAIR signal without increased perfusion, while the nasopharyngeal primary remained stable. Quantitative ratios and positron emission tomography (PET)/magnetic resonance spectroscopy (MRS) were unavailable, which is a limitation of this report.
Fluoroethyltyrosine PET is the most accurate test for distinguishing radionecrosis from recurrence [4], whereas MRI remains more accessible in Brazil; spectroscopy may show decreased choline/N-acetylaspartate ratios and increased lactate/lipid peaks, while perfusion MRI demonstrates hypoperfusion in radionecrosis versus hypervascularity in recurrence [3]. 18F-fluorodeoxyglucose PET may also assist, with reduced uptake in radionecrosis [2]. Corticosteroids are the first-line treatment; refractory cases may benefit from bevacizumab, hyperbaric oxygen therapy, laser therapy, or surgery, with consideration of risks such as hypertension and thromboembolism [2, 3].
Supplementary Information
Acknowledgments
None.
Footnotes
Ethics statement: No ethical issues arose in relation to this work that would require ethics committee approval or a separate ethics statement.
Author contributions: M.L.R.: data collection, writing, and analysis; A.M.S.: review and writing; L.E.M.M.: review and critical input; L.G.C., J.A.D.: review and critical input.
Conflict of interest: The authors declare no conflicts of interest.
Supplementary material: Supplementary materials are available on journal’s website.
Funding: No funding was received for this work.
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