患者常因肿瘤对周围组织的质量效应或远处转移的发展而出现症状。然而，有些患者可能呈现出不可归因于直接肿瘤侵袭的临床症状。特别是，某些肿瘤可能释放物质，如激素或细胞因子，或触发恶性和正常体细胞之间的免疫交叉反应，导致被广泛称为肿瘤并发综合征（PNSs）的特征性临床表现。近年来，医学方面的进展提高了对PNSs发病机制的理解和增强了其诊断和治疗能力。据估计，有癌症的患者中有8%会发展成PNSs。多样的器官系统可能会受到影响，尤其是神经、肌肉骨骼、内分泌、皮肤、胃肠和心血管系统。了解各种PNSs是必要的，因为这些综合征可能先于肿瘤的发展而出现，使患者的临床表现变得复杂，显示肿瘤预后，或被误认为是转移扩散。影像学医师应该熟悉常见PNSs的临床表现和适当的影像检查选择。其中许多PNSs具有可帮助确定正确诊断的影像特征。因此，这些PNSs的关键放射学发现以及在影像检查中可能遇到的诊断陷阱非常重要，因为它们的检测可以促进早期发现潜在的肿瘤，揭示早期复发，并启用监测患者对治疗的反应。© RSNA，2023这篇文章的测验问题可在补充材料中找到。

Patients often have symptoms due to the mass effect of a neoplasm on surrounding tissues or the development of distant metastases. However, some patients may present with clinical symptoms that are not attributable to direct tumor invasion. In particular, certain tumors may release substances such as hormones or cytokines or trigger an immune cross-reactivity between malignant and normal body cells, resulting in characteristic clinical features that are broadly referred to as paraneoplastic syndromes (PNSs). Recent advances in medicine have improved the understanding of the pathogenesis of PNSs and enhanced their diagnosis and treatment. It is estimated that 8% of patients with cancer develop a PNS. Diverse organ systems may be involved, most notably the neurologic, musculoskeletal, endocrinologic, dermatologic, gastrointestinal, and cardiovascular systems. Knowledge of various PNSs is necessary, as these syndromes may precede tumor development, complicate the patient's clinical presentation, indicate tumor prognosis, or be mistaken for metastatic spread. Radiologists should be familiar with the clinical presentations of common PNSs and the selection of appropriate imaging examinations. Many of these PNSs have imaging features that can assist with arriving at the correct diagnosis. Therefore, the key radiographic findings associated with these PNSs and the diagnostic pitfalls that can be encountered during imaging are important, as their detection can facilitate early identification of the underlying tumor, reveal early recurrence, and enable monitoring of the patient's response to therapy. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.