腹腔内淋巴结外滤泡树突细胞肉瘤的临床病理学分析

目的探讨腹腔内结外滤泡树突细胞肉瘤的临床病理学特征、免疫表型及与EB病毒感染的相关性。方法分析4例腹腔内结外滤泡树突细胞肉瘤的临床和形态特点,采用CD21、CD23、CD35、波形蛋白、S-100蛋白、上皮细胞膜抗原（EMA）、CD68、CD34、CD117、HLA-DR、CD1a、结蛋白和d-平滑肌肌动蛋白等抗体进行免疫组织化学标记（EnVision法）,采用原位杂交检测EBER。结果患者发病年龄28-63岁（平均42岁）,男性3例,女性1例。临床上表现为腹部不适、腹痛和腹部肿块。影像学检查显示,1例患者同时含有2个病灶,分别位于胃黏膜下和肝左叶,另3例表现为腹腔内肿块,术后显示分别位于阑尾、空肠系膜和大网膜。2例在术前被诊断为胃肠道间质瘤。大体上,肿瘤呈结节状,平均直径为10．8cm,3例肿瘤内可见明显的坏死灶。镜下4例非肝脏性肿瘤均由胖梭形、卵圆形至上皮样细胞组成,可见散在的多核瘤细胞。瘤细胞主要呈席纹状、旋涡状或条束状排列,部分区域呈片状分布。肿瘤内可见散在的淋巴细胞,常围绕血管分布,并与瘤细胞形成双相细胞性形态。2例肿瘤显示明显的异型性,核分裂象易见（包括病理性）。3例肿瘤内可见凝固性坏死。1例肝脏肿瘤由大量的慢性炎性细胞和散在的异形大细胞组成,呈炎性假瘤样。免疫组织化学标记显示,瘤细胞均弥漫强阳性表达CD21、CD23和波形蛋白,部分表达CD35、S-100蛋白、CD68、HLA-DR和EMA,不表达CD34和CD117。2例EBER病毒检测均为阴性。结论发生于腹腔内的结外滤泡树突细胞肉瘤非常少见,熟悉其特征性的病理形态和免疫表型有助于与腹腔内其他类型梭形细胞肿瘤（特别是胃肠道间质瘤）的鉴别诊断。除经典型外,发生于肝脏者可呈炎性假瘤样形态,易被误诊。腹腔内非肝脏性滤泡树突细胞肉瘤与EB病毒感染的关系并不密切。

Clinicopathologic study of intraabdominal extranodal follicular dendritic cell sarcoma

OBJECTIVE: To study the clinicopathologic features and immunophenotype of intraabdominal extranodal follicular dendritic cell sarcoma (FDCS) and the relationship with Epstein-Barr virus (EBV). METHODS: The clinical and histologic features of 4 cases of FDCS were evaluated. Immunohistochemical study was performed using standard EnVision method for CD21, CD23, CD35, S-100 protein, CD68, HLA-DR, vimentin, epithelial membrane antigen, desmin, CD34 and CD117. In-situ hybridization for EBV-encoded RNA (EBER) was carried out in 2 cases. RESULTS: The age of patients ranged from 28 to 63 years (mean=42 years). The male-to-female ratio was 3:1. The clinical presentation was abdominal discomfort, pain or mass. Radiologic examination revealed concurrent lesions in stomach and left lobe of liver in 1 patient, while non-specific intraabdominal masses were detected in the remaining cases (in which the tumor was later found to be located in the appendix, mesentery of jejunum and omentum). Two cases were misdiagnosed as gastrointestinal stromal tumor before operation. Grossly, the tumors appeared as large solid nodules, with a mean diameter of 10.8 cm. Three of the cases showed areas of necrosis. Histologically, there were plump spindle, ovoid to epithelioid cells associated with scattered multinucleated giant cells. The tumor cells were arranged mostly in storiform pattern, whorls, fascicles or solid sheets. Lymphocytic infiltrates with perivascular cuffing were noted in all cases, resulting in a distinctive biphasic pattern. Two tumors showed significant cytologic atypia, with mitotic figures (including atypical mitotic figures) readily demonstrated. The remaining case (occurring in liver) was composed of scattered large atypical cells embedded in a dense inflammatory background, mimicking inflammatory pseudotumor. Immunohistochemical study showed that all cases were positive for CD21, CD23 and vimentin. There was focal expression of CD35, S-100 protein, CD68, HLA-DR and epithelial membrane antigen. The staining for CD34 and CD117 was negative. In-situ hybridization for EBER was negative in 2 cases tested. CONCLUSIONS: Intraabdominal extranodal FDCS is extremely rare. Familiarity with its characteristic histologic features and immunophenotype is important in distinguishing the tumor from other intraabdominal spindle cell lesions (such as gastrointestinal stromal tumor). Hepatic FDCS may show inflammatory pseudotumor-like features, resulting in misinterpretation. Non-hepatic intraabdominal FDCS seems to have little association with EBV infection.