Josip E, Kremser C, Haider B, Thaler M, Dammerer D, Henninger B
Department of Radiology, Medical University of Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria.
Department of Orthopedics and Traumatology, Medical University of Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria.
Skeletal Radiol. 2022 Apr;51(4):819-827. doi: 10.1007/s00256-021-03889-3. Epub 2021 Aug 26.
To evaluate magnetic resonance imaging (MRI) characteristics of simple and aneurysmal bone cysts (SBC/ABC) of the proximal humerus and the intermittent difficulty in the imaging differentiation between the two in daily clinical routine.
MR images of 26 patients with suspected SBC/ABC in the proximal humerus were retrospectively assessed by two independent radiologists blinded to the final histological result. Based on a standard MRI protocol, different morphologic features and signal intensities of the lesion on non-enhanced and enhanced sequences were documented. The radiological diagnosis was correlated with histology.
Eighteen patients had the image-based diagnosis of an SBC, yet the histology confirmed only 12, the residual 6 were identified as an ABC, despite the imaging criteria corresponding unambiguously to the former. One of the main reasons was the unicameral morphology of lesions, found in 9/14 (64.3%) cases of all ABCs, i.e., in 19/26 cases in total. Therefore, the sensitivity of the radiological diagnosis was moderate (57.14%), yet specificity very high (100%). In total, 69.2% (18/26) presented with a pathological fracture at admission, which correlated strongly with both circumferential (MCC = 0.65, p = 0.01) and septal (MCC = 0.42, p = 0.06) enhancement patterns. Circumferential enhancement was also found to correlate strongly with the histological diagnosis, being recognized in all cases of ABC (MCC = 0.44, p = 0.06).
MRI characteristics of ABCs/SBCs in the proximal humerus are indifferent and ABCs may morphologically present as SBCs. Radiologists should be aware of the different, often confusing presentation of both entities in daily clinical routine.
评估肱骨近端单纯性骨囊肿和动脉瘤样骨囊肿（SBC/ABC）的磁共振成像（MRI）特征，以及在日常临床工作中两者在影像鉴别上的间歇性困难。
对26例疑似肱骨近端SBC/ABC患者的MR图像进行回顾性评估，由两名独立的放射科医生进行，他们对最终的组织学结果不知情。基于标准MRI协议，记录病变在非增强和增强序列上的不同形态特征和信号强度。将放射学诊断与组织学结果进行关联。
18例患者的影像诊断为SBC，但组织学仅证实了12例，其余6例被鉴定为ABC，尽管影像标准明确符合前者。主要原因之一是病变的单房形态，在所有ABC病例的9/14（64.3%）中出现，即总共26例中的19例。因此，放射学诊断的敏感性中等（57.14%），但特异性非常高（100%）。总共69.2%（18/26）的患者入院时出现病理性骨折，这与周向（MCC = 0.65，p = 0.01）和分隔（MCC = 0.42，p = 0.06）增强模式密切相关。还发现周向增强与组织学诊断密切相关，在所有ABC病例中均有发现（MCC = 0.44，p = 0.06）。
肱骨近端ABC/SBC的MRI特征无明显差异，ABC在形态上可能表现为SBC。放射科医生在日常临床工作中应注意这两种病变的不同且常易混淆的表现。
