软骨样脂肪瘤1例报道及文献复习

Chondroid lipoma:a case report and review of literature

目的探讨软骨样脂肪瘤的临床、病理学特点和鉴别诊断。方法报道1例右小腿软骨样脂肪瘤的临床资料、光镜、组化、免疫组化及电镜观察结果,结合文献讨论。结果镜下见肿瘤由3种成分以不同比例混合构成:①较成熟脂肪细胞体积小的单泡状和多泡状脂肪母细胞,胞质淡染为主,少数细胞呈嗜酸性,核形多样,无异型性及核分裂象,排列成片状和巢状;②脂肪母细胞间黏液透明性软骨样基质;③多少不等的成熟脂肪细胞。PAS染色见脂肪母细胞的胞质内含许多可被淀粉酶消化的深红染颗粒,提示存在糖原。AB染色见黏液透明性软骨样基质呈阳性反应,并部分耐透明质酸酶消化,提示含有硫酸软骨素。脂肪母细胞和成熟脂肪细胞表达S-100蛋白,其中脂肪母细胞对S-100蛋白的表达与脂肪母细胞分化成熟程度相关。电镜观察可见处于不同发育阶段的脂肪母细胞,脂肪母细胞周围被絮状的软骨样基质围绕。结论软骨样脂肪瘤是一种十分罕见的良性脂肪细胞肿瘤的特殊类型,具有独特的组织学形态,应注意与黏液型脂肪肉瘤和骨外黏液样软骨肉瘤等肿瘤鉴别。

Purpose To investigate the clinicopathologic features and differential diagnosis of chondroid lipoma. Methods One case of chondroid lipoma in right leg was observed by histologic, histochemical, immunohistochemical staining and was examined by electron microscopy, and related literature was also reviewed. Results Histologically, the tumor was composed of three main components. First, lipoblasts arranged in sheets and nests, containing single or numerous intracytoplasmic lipid vacuoles, smaller than mature adipocytes in size. Second, the myxohyabne matrix with the appearance of chondroid between the lipoblasts. Third, a variable amount of mature adipocytes. Histochemically, PAS stain revealed the presence of abundant glycogen in the lipoblasts, which disappeared after digestion of diastase. The myxohyaline matrix stained with alcian blue and was partially resistant to hyaluronidase digestion. Immunohistochemical staining revealed that the lipoblasts and mature adipocytes stained uniformly for vimentin. S-100 protein immunoreactivity was found in mature adipocytes and some lipoblasts, this staining was more stronger with increasing adipocytic maturation. Ultrastructurally, there were some lipoblasts in different development stage and some mature adipocytes. Chondroid matrix was found around lipoblasts. Conclusions Chondroid lipoma is a rare subtype of benign adipocytic tumors with some unique morphological features. It should be distinguished from myxoid liposarcoma and extraskeletal myxoid chondrosarcoma.