目的：探讨低度恶性纤维黏液样肉瘤(low-grade fibromyxoid sarcoma，LGFMS)的临床病理特征和诊断要点。方法：分析3例LGFMS的临床资料，观察组织学形态、免疫表型及分子病理检测结果，讨论鉴别诊断并复习相关文献。结果：患者均为女性，中位年龄57岁，肿瘤分别位于右侧膝关节前方、右侧乳腺和左侧上颌窦。肿块最大径为2.2~10.0 cm，边界欠清，似有包膜，切面灰白，部分区域呈半透明状，质中有黏液感。镜下见肿瘤组织主要由梭形纤维母细胞样细胞构成，包括两种形态区域，其一为细胞稀疏的胶原样区域；其二为细胞相对较丰富的黏液样区域。肿瘤组织中可见较多弓形血管并伴有血管周玻璃样变性。瘤细胞形态温和，无明显异型性，核分裂象罕见。免疫组织化学染色结果示：vimentin，MUC4，CD99及bcl-2阳性表达，SMA，desmin，S100，CD34，ALK及myogenin阴性表达。发生于右侧乳腺的病例行荧光原位杂交(fluorescent in situ hybridization，FISH)检测，检出FUS基因易位。发生于右侧膝关节和乳腺的2个病例分别随访20个月和51个月，患者均无瘤生存。发生于左侧上颌窦的病例于手术后12个月死亡。结论：LGFMS常见于年轻人，但各年龄段患者均可受累。好发部位为下肢近端和躯干，少见于头颈部和乳腺。LGFMS具有温和的多样性的组织学形态，容易误诊为具有黏液样结构的其他梭形细胞肿瘤。LGFMS具有转移和复发的恶性生物学行为，治疗上需对肿块作完整切除并长期随访观察。
Clinicopathologic analysis of low-grade fibromyxoid sarcoma
Objective: To explore clinicopathologic characteristic and diagnostic highlight of low-grade fibromyxoid sarcoma. Methods: Clinical data on 3 cases of low-grade fibromyxoid sarcoma were analyzed. Histopathologic change, immunophenotype and detected result of molecular pathology were observed. Differential diagnosis was discussed and related literatures were reviewed. Results: All of the three patients were female and mean age was 57 years old. Tumors were located in anterior right knee joint, right mammary gland and left maxillary sinus respectively. Tumor sizes varied from 2.2–10.0 cm. The tumor appeared as a well-defined mass with pelicula. Cross section was grayish-white and part of the section showed translucent appearance. The mass had a moderate texture like mucus. The tumor was constituted with spindle cells resembled as fibroblasts and included two kinds of morphologic changes which were collagen zone with sparse cells and myxoid zone with rich cells. There were more curvilinear capillaries accompanied with perivascular hyaline degeneration. The spindle tumor cells had mild appearance with no more heteromorphism and mitosis was rare. Immunohistochemistry staining result showed that the tumor cells were positive for Vimentin, MUC4, CD99 and bcl-2, but negative for SMA, desmin, S100, CD34, ALK and myogenin. FUS gene rearrangement was detected by FISH in the case original from right mammary gland. Two patients who had LGFMS in right knee and mammary gland were followed up for 20 months and 51 months, and both of them had a favorite condition. However, the patient with LGFMS in left maxillary sinus was dead in 12 months after operation. Conclusion: LGFMS typically affected young adults. However, patients of any age could be affected. This tumor commonly arose in the inferior proximal extremities or trunk, but rarely in the head and neck or mammary gland. LGFMS had mild and various histological appearance and was easily misdiagnosed as other spindle cell tumors with myxoid structure. LGFMS presented malignant biological behaviour as metastasis and recurrence, therefore, choice of treatment was radical, wide margin surgical excision and long-term following up was necessary.