Nagano Satoshi, Yokouchi Masahiro, Setoguchi Takao, Ishidou Yasuhiro, Sasaki Hiromi, Shimada Hirofumi, Komiya Setsuro
Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima-city, Kagoshima, 890-8520, Japan.
The Near-Future Locomotor Organ Medicine Creation Course (Kusunoki Kai), Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
BMC Musculoskelet Disord. 2015 Feb 22;16:36. doi: 10.1186/s12891-015-0491-8.
Well-differentiated liposarcoma (WDL)/atypical lipomatous tumor (ALT) is considered a low-grade malignancy that rarely metastasizes but should be carefully followed because recurrence or dedifferentiation may occur. It is recognized that WDL and ALT are essentially synonymous, describing lesions that are identical both morphologically and karyotypically, and that site-specific variations in behavior relate only to surgical resectability. Preoperative differential diagnosis between lipoma and ALT has been well studied because their clinical and image characteristics are very similar. We evaluated the factors that may differentiate ALTs from lipomas, and validated a tentative scoring system for the diagnosis of the 2 tumor types.
Forty-eight lipomas and 12 ALTs were included. The mean age, location and depth of the tumor as well as the compartment were not significantly different between the 2 groups. To evaluate the vascularity of the tumors, the average number of intratumoral vessels on pathological sections was calculated and compared between cases of lipoma and ALT.
The tumor size was significantly larger in ALT cases than in lipoma cases (P < 0.001). Magnetic resonance imaging (MRI) revealed septal structures in 91.6% of ALTs, whereas 20.8% of lipomas showed septa. Contrast enhancement in MRI was found significantly more often in ALTs (81.2%) than in lipomas (18.8%) (P < 0.001). We created a "ALT score" to discriminate between lipoma and ALT (0-6 points). ALT cases gave significantly higher point values (average 5.1 points) than lipoma cases (average 1.7 points) (P < 0.001). We found a significantly increased number of vessels in cases of ALT than in cases of lipoma (P = 0.001).
Our ALT score may help surgeons to differentiate a suspected ALT from a lipoma and could recommend a marginal resection in cases of suspected ALT. Increased intratumoral vascularity in ALT is reflected in the MRI findings and may play a key role in the acquisition of a malignant phenotype in adipocytic tumors.
高分化脂肪肉瘤（WDL）/非典型脂肪瘤性肿瘤（ALT）被认为是一种低级别恶性肿瘤，很少发生转移，但因其可能出现复发或去分化，故应密切随访。人们认识到WDL和ALT本质上是同义词，描述的是形态学和核型均相同的病变，且行为上的部位特异性差异仅与手术可切除性有关。由于脂肪瘤和ALT的临床及影像特征非常相似，术前对二者进行鉴别诊断已得到充分研究。我们评估了可能区分ALT与脂肪瘤的因素，并验证了一种用于诊断这两种肿瘤类型的初步评分系统。
纳入48例脂肪瘤和12例ALT。两组在肿瘤的平均年龄、位置、深度以及分区方面无显著差异。为评估肿瘤的血管情况，计算并比较了脂肪瘤和ALT病例病理切片上瘤内血管的平均数量。
ALT病例的肿瘤大小显著大于脂肪瘤病例（P < 0.001）。磁共振成像（MRI）显示91.6%的ALT有分隔结构，而20.8%的脂肪瘤有分隔。MRI上ALT的对比增强明显多于脂肪瘤（81.2% 对18.8%）（P < 0.001）。我们创建了一个“ALT评分”来区分脂肪瘤和ALT（0 - 6分）。ALT病例的得分显著高于脂肪瘤病例（平均分5.1分对1.7分）（P < 0.001）。我们发现ALT病例的血管数量显著多于脂肪瘤病例（P = 0.001）。
我们的ALT评分可能有助于外科医生将疑似ALT与脂肪瘤区分开来，并在疑似ALT的病例中建议进行边缘切除。ALT中瘤内血管增多在MRI表现中有所体现，可能在脂肪细胞性肿瘤获得恶性表型中起关键作用。
