Ossifying fibroma (OF) and fibrous dysplasia (FD) are two fibro-osseous lesions with overlapping clinicopathological features, making diagnosis challenging. In this study, we applied a whole-genome shallow sequencing approach to facilitate differential diagnosis via precise profiling of copy number alterations (CNAs) using minute amounts of DNA extracted from morphologically correlated microdissected tissue samples. Freshly frozen tissue specimens from OF (n = 29) and FD (n = 28) patients were obtained for analysis. Lesion fibrous tissues and surrounding normal tissues were obtained by laser capture microdissection (LCM), with ~30–50 cells (5 000–10 000 µm²) per sample. We found that the rate of recurrent CNAs in OF cases was much higher (44.8%, 13 of 29) than that in FD cases (3.6%, 1 of 28). Sixty-nine percent (9 of 13) of the CNA-containing OF cases involved segmental amplifications and deletions on Chrs 7 and 12. We also identified eight CNA-associated genes (HILPDA, CALD1, C1GALT1, MICALL2, PHF14, AIMP2, MDM2, and CDK4) with amplified expression, which was consistent with the copy number changes. We further confirmed a jaw lesion with a previous uncertain diagnosis due to its ambiguous morphological features and the absence of GNAS mutation as OF based on the typical Chr 12 amplification pattern in its CNA profile. Moreover, analysis of a set of longitudinal samples collected from an individual with a cellular lesion in suspicion of OF at the first surgery, recurrence and the latest malignant transformation revealed identical CNA patterns at the three time points, suggesting that copy number profiling can be used as an important tool to identify borderline lesions or lesions with malignant potential. Overall, CNA profiling of fibro-osseous lesions can greatly improve differential diagnosis between OF and FD and help predict disease progression.

骨化性纤维瘤 (OF) 和纤维性发育不良 (FD) 是两种具有重叠临床病理特征的纤维骨病变，使诊断具有挑战性。在这项研究中，我们应用全基因组浅层测序方法，通过使用从形态学相关的显微解剖组织样本中提取的微量 DNA 对拷贝数改变 (CNA) 进行精确分析来促进鉴别诊断。获取来自 OF ( n  = 29) 和 FD ( n  = 28) 患者的新鲜冷冻组织标本进行分析。病变纤维组织和周围正常组织通过激光捕获显微切割 (LCM) 获得，具有约 30–50 个细胞 (5 000–10 000 µm ²) 每个样品。我们发现 OF 病例中的 CNA 复发率（44.8%，29 个中的 13 个）远高于 FD 病例（3.6%，28 个中的 1 个）。69%（13 个中的 9 个）包含 CNA 的 OF 病例涉及 Chrs 7 和 12 的节段性扩增和缺失。我们还鉴定了 8 个 CNA 相关基因（HILPDA、CALD1、C1GALT1、MICALL2、PHF14、AIMP2、MDM2、 CDK4) 表达扩增，与拷贝数变化一致。由于其模棱两可的形态特征和基于其 CNA 谱中典型的 Chr 12 扩增模式没有 GNAS 突变作为 OF，我们进一步证实了先前诊断不确定的颌骨病变。此外，对从第一次手术时怀疑为 OF 的具有细胞病变的个体收集的一组纵向样本进行分析，复发和最近的恶性转化在三个时间点显示相同的 CNA 模式，表明拷贝数分析可用作识别临界病变或具有恶性潜能的病变的重要工具。总体而言，纤维骨病变的 CNA 分析可以大大提高 OF 和 FD 之间的鉴别诊断，并有助于预测疾病进展。