Objective: To investigate the clinicopathologic characteristics, immunophenotypes, and differential diagnostic features of extra-pleural solitary fibrous tumor (SFT) with uncommon histology. Methods: Seven cases of extra-pleural SFT with uncommon histology were collected during January 2015 and December 2016 in Zhejiang Provincal People's Hospital; the clinical and radiologic features, histomorphology, immunophenotype and prognosis were analyzed. EnVision method was used for immunohistochemical staining of STAT6, CD34 and other differential diagnosis associated markers. Results: There were five male and two female patients, age from 23 to 54 years (mean=39 years). Three tumors were located in the soft tissue of head and neck, two in trunk subcutaneous soft tissue, one in sella region, and one in the kidney. Grossly the tumors ranged from 0.4 to 8.0 cm (mean=3.1 cm). Microscopically, all three head and neck cases resembled giant cell angiofibroma/giant cell subtype SFT, and one case showed sheet-like pattern of the multinucleated syncytial cells, creating a biphasic arrangement similar to myofibroma. Both truncal tumor resembled lipomatous type SFT, with one similar to dermatofibrosarcoma protuberans and the other to atypical spindle cell lipomatous tumor. The sella tumor showed morphology of a conventional SFT with high grade sarcomatous transformation. The renal tumor demonstrated a malignant SFT with entrapped benign renal tubules, mimicking a biphase synovial sarcoma or a malignant mixed epithelial and stromal tumor. By immunohistochemistry, all seven SFTs showed diffuse and strong nuclear reactivity to antibody against STAT6. Conclusions: Extra-pleural SFTs show a significant heterogeneity of morphology and biological behavior which could cause differential confusion.Careful attention to its characteristic histomorphology with the use of STAT6 immunohistochemistry can help distinguish this tumor from its many mimickers.
目的： 探讨少见组织学类型的胸膜外孤立性纤维性肿瘤(SFT)的临床病理特征、免疫表型及鉴别诊断要点。 方法： 收集2015年1月至2016年12月就诊于浙江省人民医院/杭州医学院附属人民医院7例少见组织学类型的胸膜外SFT，总结其临床及影像学表现、组织形态学和预后，免疫组织化学采用EnVision法检测STAT6、CD34以及鉴别诊断相关的其他标志物，结合相关文献进行讨论。 结果： 5例男性，2例女性。发病年龄23～54岁，平均年龄39岁。3例位于头颈部软组织内，2例位于躯干皮下软组织，1例位于颅内蝶鞍区，1例位于肾实质内。肿瘤最大径0.4～8.0 cm(平均3.1 cm)。3例头颈部肿瘤表现为巨细胞血管纤维瘤/巨细胞型SFT，其中1例伴有合体状多核细胞成片生长，类似于双向分化的肌纤维瘤。2例躯干肿瘤表现为脂肪瘤样亚型SFT，其中1例组织学类似于隆突性皮肤纤维肉瘤，另1例类似于不典型梭形细胞脂肪瘤样肿瘤。1例鞍区肿瘤表现为普通型SFT伴高级别肉瘤样转化。1例肾肿瘤表现为恶性SFT伴有内陷的良性肾小管增生，类似于双向分化的滑膜肉瘤或恶性混合性上皮间质肿瘤。7例肿瘤均弥漫强核表达STAT6。 结论： 胸膜外SFT在组织学和生物学行为上可表现出明显的异质性，仔细的形态学观察并辅以STAT6免疫标记可助于其诊断和鉴别诊断。.
Keywords: Angiofibroma; Diagnosis, differential; Lipomatosis; STAT6 transcription factor; Solitary fibrous tumors.