恶性颗粒细胞瘤临床病理、免疫组化和超微结构观察

Malignant granular cell tumor: a clinicopathologic, immunohistochemical and ultrastructural study of three cases

目的：探讨恶性颗粒细胞瘤的病理学诊断和鉴别诊断要点及组织学起源。方法：对３例恶性颗粒细胞瘤进行临床病理、免疫组化及超微结构观察研究。结果：男性２例，女性１例，平均年龄为４９岁。部位分别为颈部１例，右大腿２例。其中２例分别于术后２年半及７年复发，并伴有区域淋巴结转移。组织学上３例与良性颗粒细胞瘤十分相似，局部区域出现梭形瘤细胞，空泡状核及明显的核仁，其中１例在肿瘤的周边部可见到瘤细胞与外周神经束支之间有直接移行关系。免疫酶标结果显示瘤细胞强阳性表达Ｓ－１００蛋白和神经特异性烯醇化酶（ＮＳＥ），１例电镜检测显示胞浆内充满膜包被复合性溶酶体。结论：对临床明显恶性而组织学上却极似良性的恶性颗粒细胞瘤，以下几点能提示恶性诊断：（１）肿瘤超过４ｃｍ；（２）核分裂象超过２个／１０ＨＰＦ；（３）核呈空泡状并有明显的核仁；（４）出现梭形瘤细胞；（５）有肿瘤性坏死。此外，免疫组化标记及超微结构观察有助于鉴别诊断及揭示组织学起源。

Purpose To define reliable criteria for diagnosis and differential diagnosis of malignant granular cell tumor (MGCT), and reaffirm the tumor origin. Methods The clinicopathologic, immunohistochemical, and electronmicroscopic features of three cases of malignant granular cell tumor were evaluated. Results The patients were two males and one female, with an average age of 49 years. One located in the right cervical area, the other two in the right thigh. Two cases recurred about two and a half, and seven years later respectively. Histologically, all three cases were extremely similar to the benign variant of GCT, while in part area, the tumor cells showed vesicular nuclei with prominent nucleoli, and tendency to an elongated spindle cell structure. A direct transition between the tumor cells and peripheral nerve fascicles was also noted. Immunostains revealed strong staining for S100 protein and neuron specific enolase (NSE). The ultrastructural study of one case demonstrated abundance of cytoplasmic membranebound “lysophagosomes”. Conclusions A distinction is warranted between BGCT and MGCT. Several microscopic features may favor a malignant diagnosis. Immunohistochemical and ultrastructural stuies are helpful in differential diagnosis and in histogenesis.