Lee Ching-Chi, Lee Jih-Chin, Huang Wen-Yen, Juan Chun-Jung, Jen Yee-Min, Lin Li-Fan
Department of Otolaryngology Head & Neck Surgery.
Department of Radiation Oncology.
Medicine (Baltimore). 2021 Feb 26;100(8):e24555. doi: 10.1097/MD.0000000000024555.
Some nasopharyngeal carcinoma (NPC) patients may present convincing radiological evidence mimicking residual or recurrent tumor after radiotherapy. However, by means of biopsies and long term follow-up, the radiologically diagnosed residuals/recurrences are not always what they appear to be. We report our experience on this "phantom tumor" phenomenon. This may help to avoid the unnecessary and devastating re-irradiation subsequent to the incorrect diagnosis.In this longitudinal cohort study, we collected 19 patients of image-based diagnosis of residual/recurrent NPC during the period from Feb, 2010 to Nov. 2016, and then observed them until June, 2019. They were subsequently confirmed to have no residual/recurrent lesions by histological or clinical measures. Image findings and pathological features were analyzed.Six patients showed residual tumors after completion of radiotherapy and 13 were radiologically diagnosed to have recurrences based on magnetic resonance imaging (MRI) criteria 6 to 206 months after radiotherapy. There were 3 types of image patterns: extensive recurrent skull base lesions (10/19); a persistent or residual primary lesion (3/19); lesions both in the nasopharynx and skull base (6/19). Fourteen patients had biopsy of the lesions. The histological diagnoses included necrosis/ inflammation in 10 (52.7%), granulation tissue with inflammation in 2, and reactive epithelial cell in 1. Five patients had no pathological proof and were judged to have no real recurrence/residual tumor based on the absence of detectable plasma EB virus DNA and subjective judgment. These 5 patients have remained well after an interval of 38-121 months without anti-cancer treatments.Image-based diagnosis of residual or recurrent nasopharyngeal carcinoma may be unreliable. False positivity, the "phantom tumor phenomenon", is not uncommon in post-radiotherapy MRI. This is particularly true if the images show extensive skull base involvement at 5 years or more after completion of radiotherapy. MRI findings compatible with NPC features must be treated as a real threat until proved otherwise. However, the balance between under- and over-diagnosis must be carefully sought. Without a pathological confirmation, the diagnosis of residual or recurrent NPC must be made taking into account physical examination results, endoscopic findings and Epstein-Barr virus viral load. A subjective medical judgment is needed based on clinical and laboratory data and the unique anatomic complexities of the nasopharynx.
一些鼻咽癌（NPC）患者在放疗后可能会出现令人信服的影像学证据，提示残留或复发肿瘤。然而，通过活检和长期随访发现，影像学诊断的残留/复发情况并不总是如其所见。我们报告了我们在这种“假瘤”现象方面的经验。这可能有助于避免因错误诊断而进行的不必要且具有破坏性的再次放疗。
在这项纵向队列研究中，我们收集了2010年2月至2016年11月期间19例经影像学诊断为残留/复发性鼻咽癌的患者，并对他们进行观察直至2019年6月。随后通过组织学或临床检查证实他们并无残留/复发病变。对影像表现和病理特征进行了分析。
6例患者放疗结束后显示有残留肿瘤，13例根据放疗后6至206个月的磁共振成像（MRI）标准被影像学诊断为复发。有3种影像模式：广泛的复发颅底病变（10/19）；持续或残留的原发病变（3/19）；鼻咽部和颅底均有病变（6/19）。14例患者对病变进行了活检。组织学诊断包括坏死/炎症10例（52.7%），伴有炎症的肉芽组织2例，反应性上皮细胞1例。5例患者没有病理证据，基于未检测到血浆EB病毒DNA以及主观判断，判定为无真正的复发/残留肿瘤。这5例患者在未接受抗癌治疗的情况下，经过38至121个月的间隔期后情况良好。
基于影像学诊断残留或复发性鼻咽癌可能不可靠。假阳性，即“假瘤现象”，在放疗后的MRI中并不罕见。如果影像显示放疗结束5年或更长时间后颅底广泛受累，情况尤其如此。与鼻咽癌特征相符的MRI表现必须在得到其他证据证明之前视为真正的威胁。然而，必须谨慎寻求诊断不足与过度诊断之间的平衡。在没有病理证实的情况下，诊断残留或复发性鼻咽癌必须考虑体格检查结果、内镜检查结果和EB病毒载量。需要根据临床和实验室数据以及鼻咽部独特的解剖复杂性进行主观的医学判断。
