Abstract：
Among all sarcoma types, liposarcoma is the most common sarcoma that develops \"dedifferentiation.\" Since its initial description by Dr Harry Evans, the spectrum of what is now acceptably included under the rubric of \"dedifferentiated liposarcoma\" (DL) has expanded, sometimes supported by cytogenetic and molecular advances. Similarly, the range of morphologic appearances considered to represent the precursor of DL, atypical lipomatous tumor (ALT)/well-differentiated liposarcoma, also has broadened, not uncommonly creating variants with significant, almost indistinguishable, morphologic overlap with occasional forms of DL, especially problematic in small biopsy specimens. More specifically, the precise criteria separating cellular forms of ALT from what some consider \"low-grade\" variants of DL remains controversial and inconsistently applied, even among individual pathologists within institutions. For this separation, the only objective and reproducible criteria historically shown to accurately predict a statistically significant difference in prognosis and survival is mitotic rate, alone or incorporated into a histologic grade [eg, Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC)], consistently identifying a higher grade neoplasm capable of metastases. While DL may have a better prognosis than other nonmyoid adult pleomorphic soft tissue sarcomas, definitive conclusions are difficult to establish due to nonuniform criteria for staging and establishing tumor size/volume of the high-grade component, compounded by variable definitions and thresholds for rendering the diagnosis of DL. If appropriate therapeutic approaches are to be applied to DL, there needs to uniform agreement regarding the histologic definition, grading, and staging of DL. Herein, is a comprehensive historical perspective on DL and ALT/well-differentiated liposarcoma, seeking to provide insights, updates, and a proposal for uniform, evidence-based guidelines.
摘要：
在所有类型的肉瘤中,脂肪肉瘤是最常见的去分化肉瘤。“自从哈里·埃文斯博士最初描述以来，现在可以接受的“去分化脂肪肉瘤”（DL）的范围已经扩大，有时得到细胞遗传学和分子进展的支持。同样，被认为代表DL前体的形态学外观范围，非典型脂肪瘤（ALT）/高分化脂肪肉瘤，也扩大了，并不罕见地创建具有重要意义的变体，几乎无法区分，形态与偶尔形式的DL重叠，在小活检标本中尤其有问题。更具体地说,将细胞形式的ALT与某些人认为的DL的“低等级”变体分开的精确标准仍然存在争议和不一致的应用，甚至在机构内的个体病理学家中。对于这种分离，历史上唯一能准确预测预后和生存率统计学显著差异的客观和可重复的标准是有丝分裂率,单独或纳入组织学分级[例如，国家癌症中心联合会(FNCLCC)]，一致确定能够转移的更高级别肿瘤。虽然DL可能比其他非肌样成人多形性软组织肉瘤有更好的预后，明确的结论是很难建立由于不统一的标准分期和确定肿瘤大小/体积的高等级成分，由变量定义和阈值组成，用于诊断DL。如果将适当的治疗方法应用于DL，需要就组织学定义达成一致，分级,和DL的分期。在这里，是对DL和ALT/高分化脂肪肉瘤的全面历史观点，寻求提供见解，更新,和制服的建议，循证指南。
