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- 请会诊！髓外硬膜下肿瘤
瘤细胞S-100,HMB45阳性,而GFAP,keratin为阴性,证实该病变为一黑色素性肿瘤.假设这是一原发性肿瘤,发生在软脑膜的类似黑色素性病变可归为三类:黑素细胞瘤,恶性黑色素瘤以及中间分化的黑色素性肿瘤.
黑素细胞瘤:常为梭形细胞,也可为弥漫的上皮样细胞.细胞具有很小的核仁,常有核沟,核分裂像很少,＜1/10HPF.富含黑色素.MIB-1标记指数在0-2%,平均0.5%
恶性黑色素瘤:梭形或上皮样细胞,大而显著的核仁,核多形性、异型性明显,常伴有广泛的坏死,色素含量不一.具有侵袭性生物学行为:弥漫浸润或形成卫星结节或侵入临近的脊髓或大脑实质.MIB-1标记指数在2-15%,平均7.8%
中间分化的黑色素性肿瘤: 诊断标准尚未很好的建立,MIB-1标记指数1-4%
尽管该例核分裂像少,缺乏坏死,富含色素以及增殖指数在2-3%之间,但该例的肿瘤细胞核仁非常明显.基于此,mamj认为该例是一非常少见的中间分化的黑色素性肿瘤.前提是要排除转移性黑色素瘤.
The neoplastic cells are immunoreactive to Abs against S100 protein and HMB45, but not immunoreaative to Abs against GFAP or keratin. These findings confirm this to be a melanocytic neoplasm. Assuming this is a primary neoplasm and not metastasis, discrete melanocytic neoplasm of leptomeninges like this can be categozed as one of three entities: (1) melanocytoma, (2) melanoma (malignant), and (3) menalocytic neoplasm of intermediate differentiation.
Melanocytoma - usually consists of spindled cells but may be diffusely epithelioid; cells have very small nucleoli and very rare mitoses if any (<1 per 10 hpf); usually heavily pigmented; often with nuclear grooves; MIB-1 labeling index between 0 and 2% (average 0.5%).
Malignant melanoma - spindled cells and epithelioid cells, large prominent nucleoli, variable nuclear size and shape, variable density of mitotic figures, variable pigmentation, may have extensive necrosis, diffuse spread, satellite nodules and invasion into nearby spinal cord or brain parenchyma; MIB-1 labeling index ranges from 2 to 15% (average 7.8%).
Melanocytic neoplasm of intermediate differentiation - diagnostic criteria are not well defined; MIB-1 labeling index usually lies between 1 and 4%.
Though this case shows rare mitoses, no necrosis, heavy pigmentation and a MIB-1 labeling index of 2-3%, the neoplastic cells have very prominent nucleoli. Based on these findings I would classify this as a probable (systemic oncologic workup is needed to rule out metastatic melanoma) primary melanocytic neoplasm of intermediate differentiation. This entity is very very rare and I have never made such a diagnosis before.
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本帖最后由 于 2007-09-28 12:17:00 编辑
My first impression is that this is a malignant neoplasm and not a common primary CNS or PNS tumor. My suspicion is malignant melanoma (more likely metastatic) or primary melanocytoma, and would do immunohistochemistry to help. S100 protein, HMB45, AE1, EMA and MIB-1 will be very informative. I await more information.
聞道有先後,術業有專攻
