Fibrous dysplasia (FD) is a benign bone disease characterized by expansile lesions that typically stabilize with age. Rarely, FD can undergo malignant transformation, presenting with atypical, rapid growth and destruction of adjacent bone. Other potential causes of rapid FD expansion include secondary lesions, such as aneurysmal bone cysts. We describe a case of an aggressive occipital lesion that presented with pain associated with diplopia and tinnitus, raising concern for malignant transformation. A massive intraosseous arteriovenous fistula was identified giving rise to an anomalous vein coursing to the cavernous sinus with compression of the abducens nerve. The vascular anomaly was mapped and after embolization symptoms resolved; a biopsy with extensive genetic analyses excluded malignancy. The differential diagnosis for expanding FD lesions includes aggressive FD, malignant transformation, and secondary vascular anomalies. In cases when traditional radiographic and histologic assessments are nondescript, use of additional radiographic modalities and genetic analyses are required to make an accurate diagnosis and guide treatment. When vascular anomalies are suspected, detailed angiography with embolization is necessary to define and treat the lesion. However, to rule out malignant transformation, genetic screening is recommended.

纤维性发育不良 (FD) 是一种良性骨病，其特征是扩张性病变，通常随着年龄的增长而稳定。很少，FD 会发生恶变​​，表现为不典型的、快速的生长和邻近骨的破坏。FD 快速扩张的其他潜在原因包括继发性病变，例如动脉瘤性骨囊肿。我们描述了一例侵袭性枕骨病变，表现为与复视和耳鸣相关的疼痛，引起人们对恶性转化的担忧。发现一个巨大的骨内动静脉瘘，导致异常静脉流向海绵窦，压迫外展神经。血管异常被绘制，栓塞后症状消失；具有广泛遗传分析的活检排除了恶性肿瘤。扩大FD病灶的鉴别诊断包括侵袭性FD、恶变和继发性血管异常。在传统放射学和组织学评估无法描述的情况下，需要使用额外的放射学方法和基因分析来做出准确的诊断和指导治疗。当怀疑有血管异常时，需要进行详细的栓塞血管造影来确定和治疗病变。然而，为了排除恶变，建议进行基因筛查。当怀疑有血管异常时，需要进行详细的栓塞血管造影来确定和治疗病变。然而，为了排除恶变，建议进行基因筛查。当怀疑有血管异常时，需要进行详细的栓塞血管造影来确定和治疗病变。然而，为了排除恶变，建议进行基因筛查。