CK阴性，提示不是上皮发生的转移性恶性肿瘤，即：不是转移癌。

S100阴性，提示不是脂肪肉瘤。

HMB45阴性，提示不是恶黑，也不是PEComa。

Ki67阳性率仅 4%，提示不是高度恶性肿瘤。

需要增加肌源性标志物和组织细胞性标志物进一步鉴别诊断。主要鉴别横纹肌样肿瘤和组织细胞肿瘤。

脂肪肉瘤。

患者较年轻，30岁，发现肿物5年，病史较长，间质薄壁血管丰富，有的血管扩张，瘤细胞围绕血管分布，首先考虑为腺泡状软组织肉瘤，建议PAS，IHC：MyoD1，TFE3等，然后排除其他如上述所涉及的有关肿瘤。

首选PEComa

病史5年，且Ki-67指数低——低度恶性，考虑血管源性

图片不清楚，至少要考虑和排查脂肪肉瘤。

Pleomorphic liposarcoma

 Definition

● Widespread high grade, pleomorphic tumor cells with some lipoblasts but no evidence of well differentiated liposarcoma

Epidemiology

● 5% of all liposarcomas

● No gender preference

● Median age 54-70 years

● Rare in childhood

● Associated with radiation therapy or neurofibromatosis

Sites

● Thigh (29%), internal trunk (21%), limb girdles (18%), upper extremity (16%), thoracoabdominal wall (10%)

● Often deep seated or extracompartmental

Treatment and prognosis

● Wide local excision or amputation with postoperative radiotherapy (AJSP 2004;28:1257), also chemotherapy

● Aggressive; often recurs locally (40%), metastasizes (40%), causes death (35%)

● 5 year overall survival 60%

● Poor prognostic factors: age 60+, truncal (central) location, deep, size >5 cm, vascular invasion, incomplete excision (AJSP 2002;26:601)

Gross description

● Often large (median 8-10 cm, up to 23 cm), multinodular, white-yellow

● Usually deep (subfascial), often myxoid or necrotic areas

Micro description

● Well circumscribed but non-encapsulated with infiltrative borders

● At least focal typical liposarcomatous areas

● Pleomorphic cells cover > 65% of cut surface with MFH-like, round cell liposarcoma-like (without vascular network), spindle cell liposarcoma-like or epithelioid cells (Mod Path 1999;12:722)

● Usually high grade with enlarged round to bizarre nuclei; tumor necrosis common; median 25 mitotic figures/10 HPF

● May have neutrophils within giant cells, hemangiopericytic foci, extra- and intracellular hyaline droplets

Positive stains

● Vimentin, S100 (lipogenic areas in 33%), smooth muscle actin (45%), CD34, keratin (21%), desmin (13%)

Electron microscopy

● Abundant coalescing lipid droplets, numerous cytoplasmic organelles

Differential Diagnoses

● Dedifferentiated liposarcoma - has well differentiated component

● MFH-pleomorphic - no definite fat vacuoles

● Pleomorphic rhabdomyosarcoma - skeletal muscle differentiation

● Metastatic carcinoma - keratin+ or other evidence of epithelial differentiation, no liposarcomatous differentiation

此外还可以IHC鉴别上皮样肉瘤。

本例可能是具有非典型性组织学特征的腺泡状软组织肉瘤
Enzinger and Weiss：The individual cells are large, rounded, or more often polygonal and display little variation in size and shape. They have distinct cell borders and one or more vesicular nuclei with small nucleoli and abundant granular, eosinophilic, and sometimes vacuolated cytoplasm. Mitotic figures are scarce. Rare pleomorphic tumors have been reported in the literature ——Evans HL: Alveolar soft-part sarcoma. A study of 13 typical examples and one with a histologically atypical component.  Cancer  1985; 55:912.
腺泡状软组织肉瘤的边缘常看见扩张的静脉，并常见脉管浸润，很类似于副节瘤或血管周细胞瘤

多形性软组织肉瘤

1脂肪肉瘤

2横纹肌肉瘤

3上皮样肉瘤

患者年轻，肿物体积不大，结合形态学及已知的免疫组化结果，考虑腺泡状软组织肉瘤。

建议补做PAS  查肿瘤细胞胞质中的结晶

期待最终的结果，病例拿出去会诊了吗？

个人考虑：透明细胞肉瘤。

HMB45在无色素性恶黑中就是阴性，我一般在诊断恶黑时会加做melan-A，还有一个抗体PNL-2诊断恶黑也是不错的。

首选脂肪肉瘤

腺泡状软组织肉瘤

首选脂肉.

不太像脂肪肉瘤

生长位子比较深，浸润纤维间质之中，诊断圆形细胞脂肪肉瘤 ，查一下免疫组化，S-100,VimE。及PCK排除一下上皮来源的印戒细胞癌。

首选圆形细胞脂肪肉瘤。

 CK,S100,HMB45均阴，Ki67 4%，

期待结果

脂肪肉瘤

圆形细胞脂肪肉瘤