目的 探讨具有黏液样变的高分化/去分化脂肪肉瘤临床病理及分子遗传学特征，并与具有相似形态的黏液纤维肉瘤相鉴别。 方法 收集河南省人民医院及解放军总医院第一医学中心2015年1月至2023年3月确诊黏液样变脂肪肉瘤29例、黏液纤维肉瘤5例，采用免疫组织化学、荧光原位杂交（FISH）检测相关指标情况，并复习文献。 结果 34例患者中男性24例，女性10例，年龄41~73岁；发病部位包括腹膜后（17例）、腹腔（9例）、下肢（5例）、阴囊（1例）、上肢（1例）和腋下（1例）。高分化脂肪肉瘤以脂肪瘤样型多见（12例）；去分化脂肪肉瘤的去分化成分包括低级别（13例）和高级别（2例）形态，呈低至高级别黏液纤维肉瘤样、隆突性皮肤纤维肉瘤样、低级别纤维肉瘤结构。29例脂肪肉瘤均具有不同比例的黏液样形态，16例伴多少不等肿瘤性坏死。黏液样形态表现为黏液样脂肪肉瘤样，呈分叶状生长，特征性的纤细、分支状毛细血管网，类似于鸡爪样形态，富含黏液的间质和肺水肿样形态，肿瘤细胞呈梭形及卵圆形，伴多少不等多空泡状脂肪母细胞。FISH法检测MDM2基因显示成簇扩增（29/29），DDIT3分离探针均未发生断裂，但显示成簇扩增（24/29）；黏液纤维肉瘤中1例存在DDIT3分离探针簇状扩增（1/5），无基因断裂，且MDM2基因无扩增。 结论 具有黏液样变的高分化/去分化脂肪肉瘤以腹膜后和腹腔最为多见，大多呈DDIT3分离探针扩增，但该扩增现象并非脂肪肉瘤特异性表现。对于穿刺标本或极少数发生在四肢的肿瘤，当组织学具有黏液间质、黏液样脂肪肉瘤样形态时，应避免误诊为黏液样脂肪肉瘤或其他具有黏液样形态的非脂肪源性肿瘤。 Objective To investigate the clinicopathological and molecular genetic characteristics of well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS) with myxoid-like morphology, and to distinguish them from myxofibrosarcoma (MFS) with similar morphology. Methods Twenty-nine cases of myxoid-like liposarcoma and 5 cases of MFS were collected from Henan Provincial People′s Hospital, Zhengzhou, China and the First Medical Center of PLA General Hospital, Beijing, China from January 2015 to March 2023. Relevant markers were detected using immunohistochemistry and fluorescence in situ hybridization (FISH). The literature was also reviewed. Results There were 24 males and 10 females, with ages ranging from 41 to 73 years. The tumor sites included retroperitoneum (n=17), abdomen (n=9), lower limbs (n=5), scrotum (n=1), upper limb (n=1) and axilla (n=1). WDLPS was commonly seen as lipomatoid type (12 cases), while the dedifferentiated components of DDLPS included low-grade (13 cases) and high-grade (2 cases) morphology, with low-high grade myxofibrosarcoma, dermatofibrosarcoma protuberans, and low-grade fibrosarcoma structures. Twenty-nine liposarcomas had various proportions of myxoid-like morphology, while 16 showed various degrees of tumor necrosis. The myxoid-like component showed myxoid pleomorphic liposarcoma (MLPS)-like morphology, lobulated growth, characteristic slender, ramified capillary network,"chicken claw-like"morphology, mucus-rich stroma and lung edema-like morphology. Tumor cells were spindle and oval, with many variable vacuolar lipoblasts. MDM2 gene amplification was detected using FISH and present in all tested cases (29/29). DDIT3 break-apart mutation was not detected, but its cluster amplification was present (24/29). Among the MFS cases, one showed cluster amplification (1/5), but no cases showed break-apart or amplification of MDM2 gene. Conclusions WDLPS/DDLPS with myxoid-like morphology is most commonly seen in the retroperitoneum and abdominal cavity and mostly harbors DDIT3 break-apart probe amplification, while this amplification is not specific to liposarcoma. For core biopsy specimens or very rare tumors in the limbs, when histology has mucinous stroma and MLPS-like morphology, misdiagnosis of MLPS or other non-lipomatous neoplasms with myxoid morphology should be avoided.
Well-differentiated/dedifferentiated liposarcoma associated with myxoid-like morphology: a clinicopathological and molecular genetic characteristics analysis of 34 cases
Objective To investigate the clinicopathological and molecular genetic characteristics of well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS) with myxoid-like morphology, and to distinguish them from myxofibrosarcoma (MFS) with similar morphology. Methods Twenty-nine cases of myxoid-like liposarcoma and 5 cases of MFS were collected from Henan Provincial People′s Hospital, Zhengzhou, China and the First Medical Center of PLA General Hospital, Beijing, China from January 2015 to March 2023. Relevant markers were detected using immunohistochemistry and fluorescence in situ hybridization (FISH). The literature was also reviewed. Results There were 24 males and 10 females, with ages ranging from 41 to 73 years. The tumor sites included retroperitoneum (n=17), abdomen (n=9), lower limbs (n=5), scrotum (n=1), upper limb (n=1) and axilla (n=1). WDLPS was commonly seen as lipomatoid type (12 cases), while the dedifferentiated components of DDLPS included low-grade (13 cases) and high-grade (2 cases) morphology, with low-high grade myxofibrosarcoma, dermatofibrosarcoma protuberans, and low-grade fibrosarcoma structures. Twenty-nine liposarcomas had various proportions of myxoid-like morphology, while 16 showed various degrees of tumor necrosis. The myxoid-like component showed myxoid pleomorphic liposarcoma (MLPS)-like morphology, lobulated growth, characteristic slender, ramified capillary network,"chicken claw-like"morphology, mucus-rich stroma and lung edema-like morphology. Tumor cells were spindle and oval, with many variable vacuolar lipoblasts. MDM2 gene amplification was detected using FISH and present in all tested cases (29/29). DDIT3 break-apart mutation was not detected, but its cluster amplification was present (24/29). Among the MFS cases, one showed cluster amplification (1/5), but no cases showed break-apart or amplification of MDM2 gene. Conclusions WDLPS/DDLPS with myxoid-like morphology is most commonly seen in the retroperitoneum and abdominal cavity and mostly harbors DDIT3 break-apart probe amplification, while this amplification is not specific to liposarcoma. For core biopsy specimens or very rare tumors in the limbs, when histology has mucinous stroma and MLPS-like morphology, misdiagnosis of MLPS or other non-lipomatous neoplasms with myxoid morphology should be avoided.
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