Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA, USA.
Am J Surg Pathol. 2012 Jul;36(7):1047-51. doi: 10.1097/PAS.0b013e3182517b96.
Pleomorphic liposarcoma (PL) is an uncommon form of liposarcoma that rarely occurs in the skin and subcutis. As its behavior in this setting is incompletely characterized, we undertook a study of a series of superficial PLs, defined as those arising or based primarily in the dermis and/or subcutis without involvement of deep structures. In addition, MDM2 gene amplification, a diagnostic signature of well-differentiated/dedifferentiated liposarcoma (WDL/DL), was evaluated to address the recent observation that this gene is amplified within PL-like areas in DL. PLs were obtained from institutional and consultation files (n=29). Cases were evaluated with respect to age, sex, location (dermis, dermis and subcutis, subcutis), size, predominant pattern (pleomorphic spindled or epithelioid), extent of lipogenic differentiation, and tumor necrosis. MDM2 amplification was analyzed using FISH on formalin-fixed, paraffin-embedded material in 26 cases. Patients ranged in age from 5 to 93 years (M:F=1.4:1). Tumors were located on the extremity (n=15), trunk (n=7), and head and neck (n=7) and involved the dermis (n=4), dermis and subcutis (n=10), and subcutis (n=15). Tumor size ranged from 0.8 to 15 cm (median=2 cm). All were mitotically active high-grade sarcomas [FNCLCC grade 2 (n=23) or 3 (n=6)] with either a pleomorphic spindled (n=24) or an epithelioid pattern (n=5) with variable extent of lipogenic differentiation [<25% (n=15), 25% to 50% (n=9), >50% (n=5)]. Necrosis was present in 3 cases. MDM2 gene amplification was present in 3 of 26 cases. Follow-up information in 24 cases (range=1 to 192 mo; median=48 mo; mean=59 mo) revealed local recurrences (4/24) but no metastasis or death from disease. We conclude that cutaneous and subcutaneous PLs, despite their high grade, have a much more favorable outcome compared with their deep-seated counterparts, most likely attributed to their small size and superficial location. The low incidence of MDM2 gene amplification in our series indicates that most superficial PLs are unrelated to WDL/DL. PL likely evolves by way of more than 1 molecular pathway.
多形性脂肪肉瘤 (PL) 是一种罕见的脂肪肉瘤形式，很少发生在皮肤和皮下组织中。由于其在这种情况下的行为尚未完全确定，我们对一系列浅表 PL 进行了研究，将其定义为主要发生在真皮和/或皮下组织中而不涉及深部结构的肿瘤。此外，还评估了 MDM2 基因扩增，这是一种分化良好/去分化脂肪肉瘤 (WDL/DL) 的诊断特征，以解决最近观察到的在 DL 中的类似 PL 区域中扩增该基因的现象。PL 取自机构和咨询档案（n=29）。评估了病例的年龄、性别、位置（真皮、真皮和皮下组织、皮下组织）、大小、主要模式（多形性梭形或上皮样）、脂肪生成分化程度和肿瘤坏死情况。在 26 例福尔马林固定、石蜡包埋的材料中使用 FISH 分析 MDM2 扩增。患者年龄为 5 至 93 岁（M:F=1.4:1）。肿瘤位于四肢（n=15）、躯干（n=7）和头颈部（n=7），累及真皮（n=4）、真皮和皮下组织（n=10）和皮下组织（n=15）。肿瘤大小为 0.8 至 15cm（中位数=2cm）。所有肿瘤均为有丝分裂活跃的高级别肉瘤[FNCLCC 分级 2（n=23）或 3（n=6）]，具有多形性梭形（n=24）或上皮样形态（n=5），脂肪生成分化程度不同[<25%（n=15），25%至 50%（n=9），>50%（n=5）]。3 例有坏死。26 例中有 3 例 MDM2 基因扩增。24 例的随访信息（范围为 1 至 192 个月；中位数为 48 个月；平均值为 59 个月）显示局部复发（4/24），但无转移或死于疾病。我们得出结论，尽管皮肤和皮下组织 PL 分级较高，但与深部组织相比，其预后要好得多，这很可能归因于其体积较小和位置较浅。在我们的研究系列中，MDM2 基因扩增的发生率较低，表明大多数浅表 PL 与 WDL/DL 无关。PL 可能通过多种分子途径演变。
