Yu JiaDe, Sokumbi Olayemi
Department of Dermatology, Medical College of Wisconsin, Milwaukee, WI, USA.
J Cutan Pathol. 2016 Jun;43(6):526-530. doi: 10.1111/cup.12692. Epub 2016 Apr 5.
Liposarcomas are one of the most common sarcomas arising in the extremities of the elderly. Various subtypes of liposarcomas include well-differentiated liposarcomas, dedifferentiated liposarcomas, myxoid liposarcomas and pleomorphic liposarcomas. Pleomorphic liposarcomas are the rarest subtype and have the highest malignant potential compared with the other subtypes of liposarcomas. Metastases to internal organs are common but cutaneous metastasis is very rare with only few cases in the literature. We present a patient with a known diagnosis of stage IV metastatic liposarcoma who presented to our clinic with a rapidly growing nodule on the scalp. A biopsy showed a high-grade poorly differentiated spindled cell neoplasm sparing the epidermis with scattered lipoblasts. Immunostaining for S100, SOX10, and MNF-116 were negative. To further characterize the neoplasm, immunostaining with MDM-2 was performed and was also found to be negative. The histologic appearance, immunohistochemical staining, and clinical history support a diagnosis of metastatic pleomorphic liposarcoma to the scalp. The diagnosis of pleomorphic liposarcoma is challenging. It is often difficult to differentiate from myxofibrosarcoma or other high-grade pleomorphic sarcomas based on histology alone. However, the presence of bizarre lipoblasts and negative MDM-2 staining can be helpful clues to differentiate this neoplasm from histologic mimics.
脂肪肉瘤是老年人四肢最常见的肉瘤之一。脂肪肉瘤的各种亚型包括高分化脂肪肉瘤、去分化脂肪肉瘤、黏液样脂肪肉瘤和多形性脂肪肉瘤。多形性脂肪肉瘤是最罕见的亚型，与其他脂肪肉瘤亚型相比，其恶性潜能最高。转移至内脏很常见，但皮肤转移非常罕见，文献中仅有少数病例报道。我们报告一名已知诊断为IV期转移性脂肪肉瘤的患者，该患者因头皮上一个迅速生长的结节前来我们诊所就诊。活检显示为高级别低分化梭形细胞肿瘤，不累及表皮，有散在的脂肪母细胞。S100、SOX10和MNF-116免疫染色均为阴性。为进一步明确肿瘤特征，进行了MDM-2免疫染色，结果也为阴性。组织学表现、免疫组化染色及临床病史支持头皮转移性多形性脂肪肉瘤的诊断。多形性脂肪肉瘤的诊断具有挑战性。仅根据组织学往往难以与黏液纤维肉瘤或其他高级别多形性肉瘤相鉴别。然而，奇异脂肪母细胞的存在以及MDM-2染色阴性可能有助于将该肿瘤与组织学上的相似肿瘤区分开来。
