PDF(Pubmed)
Abstract：
The intramuscular subtype of nodular fasciitis (NF) is rare with lesions normally not more than 2 cm in size and characterized by pseudosarcomatous morphology. We report a case of a 27-year-old man with a large-size intramuscular NF. The patient came for treatment complaining of an increasingly enlarged mass in the left upper arm for 4 months. Magnetic resonance imaging (MRI) confirmed the presence of a well-defined tumor measuring 5 cm within the outer edge of the middle humerus. Microscopically, the neoplasm was rich in fibroblasts and myofibroblasts in an interlaced pattern with high mitotic index and evident multinuclear giant cells. Erythrocyte extravasation was easily seen in the stroma. The tumor border was infiltrative. Immunohistochemically, the tumor cells were positive for smooth muscle actin (SMA) and negative for cytokeratin, desmin, H-Caldesmon, CD34, S100, ALK, and β-catenin. Fibrosarcoma was highly suspected by histopathological and immunohistochemical examination. Molecular detection demonstrated evidence of ubiquitin-specific peptidase 6 (USP6) gene rearrangement in this tumor. Based on the findings, the tumor was diagnosed as intramuscular NF. At 56 months after the initial surgery, the patient had recovered with no evidence of recurrence or metastasis. Large-size intramuscular NF is very rare and easily overdiagnosed as malignant tumor due to its obvious pseudosarcomatoid pathological features. USP6 gene rearrangement detection can effectively avoid this major misdiagnosis.
摘要：
结节性筋膜炎（NF）的肌内亚型很少见，病变大小通常不超过2cm，并以假肉瘤形态为特征。我们报告了一例27岁的男性，患有大尺寸的肌内NF。患者来接受治疗，抱怨左上臂的肿块越来越大，持续了4个月。磁共振成像（MRI）证实了在肱骨中部外边缘内存在一个清晰的肿瘤，大小为5厘米。微观上,肿瘤富含成纤维细胞和肌成纤维细胞，呈交错状，有丝分裂指数高，多核巨细胞明显。在基质中很容易看到红细胞外渗。肿瘤边界呈浸润性。免疫组织化学，肿瘤细胞平滑肌肌动蛋白（SMA）阳性，细胞角蛋白阴性，desmin,H-Caldesmon,CD34,S100,ALK,和β-连环蛋白。通过组织病理学和免疫组织化学检查高度怀疑纤维肉瘤。分子检测证明了该肿瘤中泛素特异性肽酶6（USP6）基因重排的证据。根据调查结果,肿瘤诊断为肌内NF。初次手术后56个月，患者已经康复，没有复发或转移的证据。大尺寸肌内NF非常罕见，由于其明显的假性肉瘤样病理特征，容易被过度诊断为恶性肿瘤。USP6基因重排检测能有效避免这一主要误诊。
