皮肤组织一块，大小5.0×3.0×1.5cm，皮肤中央见一灰褐色突起，直径2.2cm，表面破溃，面积直径0.1cm。

CD31

Also designated platelet endothelial cell adhesion molecule-1 (PECAM-1). This is a 120-130 kD membrane glycoprotein found at endothelial cell junctions and on the surface of platelets. It plays a role in thrombosis, woudn-healing and angiogenesis. Its is a ligand for CD38.

Antibodies are effective on paraffin-embedded tissue4.

Immunohistochemical expression

• endothelial cells, including the sinusoidal endothelial cells of liver, lymph nodes and spleen which stain variably for Ulex europaeus and factor VIII-related protein

• megakaryocytes and platelets

• monocytes / macrophages

• granulocytes

• B lymphocytes, particularly of the follicular mantle2, plasma cells2 and some extramedullary plasmacytomas2

• vascular tumours: sensitivity for both benign and malignant tumours is almost 100%2,3

• Kaposi's sarcoma shows staining which is usually but not invariably confined to the angiomatoid areas, with negativity of the spindle cell areas.2 CD34 is a more sensitive marker for Kaposi's sarcoma than is CD313.

• lymphangiomas; these stain less strongly than do vascular tumours

• occasional Ewing's sarcoma/primitive neuroectodermal tumours

• rarely in carcinomas and mesotheliomas

• some lymphomas

CK5/6 P63 CD34阴性

本例会诊认为是组织细胞起源，关键是良恶性存在分歧，不知曾教授有何意见？

该患者去北京会诊。会诊医生的意见有：1.组织细胞或树突细胞增生性病变，建议免疫组化进一步明确诊断；2. 恶性肿瘤，结合免疫组化（CD21 CD35阴性）考虑为组织细胞肉瘤。

请问大家能否确诊为组织细胞肉瘤，如何区别组织细胞增生性病变和组织细胞肉瘤，诊断组织细胞肉瘤最低界限是什么？

本例有会诊结果，但几个意见不是太一致，想听听大家的意见

还有其它考虑吗？如何解释CD68的阳性，而CD34却阴性，CD31并不是血管特有的标记物，组织细胞也可以阳性啊

CK5/6 P63 HMB45 MelanA CD34阴性；S-100，CD1a个别细胞阳性；CD31部分细胞阳性，CD68阳性，vimentin阳性，CD21 CD35阴性，Ki67约15%

CK5/6 ,P63阴性 S-100个别细胞阳性， HMB45 MelanA阴性。病史2月，直径2cm，年龄80