这些图是2008年的空肠肿瘤,2009年病人有肝转移.

CK: 1-2% tumor cells positive

EMA: 1% tumor cells positive

S100: >90% tumor cells positive

你的鉴别诊断是? 还需要那些免疫组化和检查?

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是的。

 这个肿瘤的其他免疫组织化学:

Melan-A" negative

HMB45: negative

tyroinase: negative

MITF-1: negative

chromogranin: negative

CD56: negative

CD99: negative

CD21/CD23/CD35: 未做

desmin: negative

actin: negative

这个肿瘤形态学上不象ＰＮＥＴ（不够primitive). 　　

ＰＥＣＯＭＡ是个好的鉴别诊断，但是没有那种常见的血管模式。　指状突树突细胞肉瘤也可以考虑，因为核确实有核沟。

关键在于透明的细胞在这儿。最后我做了个ＦＩＳＨ，有ＥＷＳ的异位，所以结合形态学，免疫组织化学和ＦＩＳＨ的结果，最后诊断为：透明细胞肉瘤（clear cell sarcoma）.

本例病人没有恶黑的病史。

胃肠道的clear cell sarcoma有很多被误诊为恶黑（本例病例也被外院误诊为恶黑）。见以下的２篇文献。　

1.    Lyle PL, Amato CM, Fitzpatrick JE, Robinson WA. Gastrointestinal melanoma or clear cell sarcoma? Molecular evaluation of 7 cases previously diagnosed as malignant melanoma. Am J Surg Pathol. 2008;32(6):858-66.

ABSTRACT: lear cell sarcoma (CCS) is a rare tumor classically associated with the tendons and aponeuroses of distal extremities of young adults. CCS and malignant melanoma (MM) share immunohistochemical profiles and ultrastructural features, but classic CCS has characteristic morphology with low mitotic activity and minimal pleomorphism. Occasional cases show pleomorphism, high mitotic index, and/or melanin pigmentation, making CCS indistinguishable from MM based on morphology. However, CCS is genetically distinct owing to its consistent association with a t(12;22)(q13;q12) chromosomal translocation, leading to the formation of the EWS/ATF1 fusion transcript. This translocation has never been documented in cutaneous melanoma, and thus is regarded as specific for CCS. Recent evidence suggests that primary "malignant melanomas" in unusual anatomic sites, most notably the gastrointestinal (GI) tract, may be CCS. This is supported by 11 cases of primary GI CCS with the t(12;22) translocation. We used reverse-transcription polymerase chain reaction and fluorescence in situ hybridization to examine whether a proportion of cases diagnosed as MM of the GI tract in patients without a history of cutaneous MM actually represent primary GI CCS. In total, we examined 7 cases: Four with no prior history of MM, 2 with histories of cutaneous MM, and 1 with an anal MM. All 4 cases for which there was no history of cutaneous/mucosal MM harbored the EWS/ATF1 fusion transcript. We report the largest series of GI CCS and have shown that molecular studies may be warranted in cases that otherwise seem to represent MM of unusual primary locations.

2. Covinsky M, Gong S, Rajaram V, Perry A, Pfeifer J. EWS-ATF1 fusion transcripts in gastrointestinal tumors previously diagnosed as malignant melanoma. Hum Pathol. 2005;36(1):74-81.

Clear cell sarcoma (CCS) is classically a deep soft tissue tumor associated with tendons or aponeuroses, although cases of primary CCS of the gastrointestinal (GI) tract have recently been reported. Because it is difficult to distinguish CCS from metastatic melanoma based on morphology, immunohistochemical profile, and ultrastructural features, it is possible that some GI tumors diagnosed as metastatic melanoma actually represent primary GI CCS. Because the EWS-ATF1 fusion transcript and the associated t(12;22)(q13;q12) translocation occur in CCS but not cutaneous melanoma, we investigated the use of molecular-based testing for discriminating CCS from metastatic melanoma (MM) in GI tumors. METHODS: Patients with GI tumors diagnosed as MM were identified from departmental files. The tumors were tested for the EWS-ATF1 fusion transcript by RT-PCR and for t(12;22)(q13;q12) by fluorescence in situ hybridization. RESULTS: Detailed review of medical records revealed that 16 (80%) of the 20 had a documented history of cutaneous melanoma. Two cases (10%) harbored the EWS-ATF1 fusion transcript, and fluorescence in situ hybridization confirmed the presence of t(12;22) in both cases. Of the 2 positive tumors, 1 developed in a patient who had no history of cutaneous melanoma, and the other developed in a patient with a remote history of vulvar melanoma. CONCLUSION: Based on molecular genetic findings, a subset of GI tumors diagnosed as MM by routine histopathologic evaluation represents CCS.

这是一个很有意思的病例。这个肿瘤是外院来的病理, 在美国一个很有名的地方, 已诊断为转移性的恶黑了, 然后病人到我们这儿来治疗， 病人还把片字送到另外一个有名的专家那儿诊断为“副结节瘤”。按照规定（美国很多医院都是这么规定的）, 到我们这儿来治疗的病人的病理片子必须经本院的病理大夫确认诊断。

外院诊断为恶黑的根据就是S100阳性（》90%细胞），他们也做了CD117和其他很多的免疫组织化学染色，但是最后诊断为恶黑。 其他的检查： AE1/3 (-), desmin (-), SMA(-), CD34(-), melan-A (-).  HMB45没有做。 外院他们的鉴别诊断： 恶黑，神经内分泌肿瘤， GIST，上皮癌。

但是我拿到这个病例时， 我觉得不是恶黑，也不象“副结节瘤”。 所以我也开始把上皮样的GIST放在最高的位置,  重复了CD117，CD34和SMA， 结果是阴性，因为有5%的GIST会阴性的（由于PDGFR-ALPHA突变），所以又做了C-KIT和PDGFR-ALPHA的基因突变的分析，结果是没有突变。也考虑过以上大家建议的那些肿瘤： 神经内分泌肿瘤，上皮样的MPNST，sex-cord stromal tumor etc.  所以也做了一些IHC： chromogranin (-), synaptophysin 20% cell positive, CD56 (-), inhibin (-), inhibin (-), CK 见上，EMA 见上。 以上的染色都不支持神经内分泌肿瘤, sex-cord stromal tumor。 虽然S100染色表明必须把上皮样的MPNST考虑在内，但是一般MPNST的S100染色不是几乎所有的细胞都染。

所以到这儿我也排除了上皮样的GIST，也不认为上皮样的MPNST是好的诊断。上皮样的SS也不太象。这个肿瘤也不是淋巴瘤。到这时我就想这可能是一个少见的肿瘤在少见的部位了，考虑其他的可能具有这样形态学的肿瘤。所以我又做了一个检查，最后确诊了这个肿瘤。

大家再想想其他的鉴别诊断，我过几天给出答案。

这个肿瘤形态学很有意思, 我也是一步步的排除才作出正确诊断, 从诊断过程中或许我们都能学点东西，从诊断过程中学西可能有时比单纯的告诉一个答案可能更有意义。