Abstract:

Objective  To summarize clinical and pathological features, diagnosis and differential diagnosis, as well as treatment and prognosis through analyzing one case of collision tumor in the sellar region (pituitary adenoma combined with malignant triton tumor).  Methods and Results  A 59-year-old male was admitted to hospital with decreased vision, vision field defect and dizziness. Head MRI demonstrated space-occupying lesion in the sellar region. Therefore, the patient underwent a transsphenoidal surgery with subtotal tumor resection. Three months later, the patient was admitted to hospital again with vision loss and headache. Head CT demonstrated space-occupying lesions in sellar/suprasellar region, therefore, the patient underwent saddle tumor resection. Histological findings revealed that the tumor was composed of two different types of tumors, one was pituitary adenoma with epithelial cells arranged in nest-like and trabecular pattern, and the other was diffused spindle cell tumor. The two tumors were distributed separately or mixed togenther. The morphology of spindle cell tumor was bland with scarce mitosis in the first surgery, whereas additional features including increased cell density, dark nuclei, frequent mitosis and scattering distributed rhabdomyoblasts were found in the second surgery. Immunohistochemically, the pituitary adenoma (epithelial cell region) cells were positive for cytokeratin 8 (CK8), chromogranin A (CgA), synaptophysin (Syn) and thyroid stimulating hormone (TSH), while the malignant triton tumor cells (spindle cell region) were positive for CD56, CD57, calretinin (CR) and focally positive for S-100 protein (S-100), desmin (Des) and myogenin. Ultrastructural findings revealed abundant rough endoplasmic reticules and secretary granules in the cytoplasm of pituitary adenoma cells, and discontinuous basal lamina located outside the spindle cell membrane. The final pathological diagnosis was sellar collision tumor (non-functional TSH adenoma combined with malignant triton tumor). The patient died 6 months after the second surgery.  Conclusions Collision tumor of the sellar region with pituitary adenoma and malignant triton tumor is a rare tumor which can hardly be diagnosed by clinical and neuroimaging examination. The diagnosis relies on morphological characteristics, immunophenotype and ultrastructural features. The prognosis of collision tumor with malignant triton tumor component is poor.

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目的 报道1 例垂体腺瘤合并恶性蝾螈瘤的鞍区碰撞瘤患者，结合相关文献，总结其临床病理学特征、诊断与鉴别诊断、治疗及预后。方法与结果 男性患者，59 岁，因双眼视力下降、视野缺损伴头晕首次入院，头部MRI显示鞍区占位性病变。遂行鼻内镜下经鼻蝶入路垂体腺瘤切除术，手术部分切除肿瘤。术后3 个月患者出现视力下降至失明伴头痛再次入院，头部CT 显示鞍区和鞍上占位性病变，遂行开颅鞍区和鞍上肿瘤切除术。两次手术标本组织学形态观察，肿瘤组织由呈巢团状和梁索状排列的上皮细胞和弥漫性分布的梭形细胞组成，两种肿瘤成分单独或交错分布，首次手术标本中梭形细胞形态温和，核分裂象罕见，再次手术标本中梭形细胞密度增加，胞核深染，核分裂象易见，可见散在分布的胞质红染的横纹肌样分化。免疫组织化学染色，垂体腺瘤成分（上皮细胞区域）细胞角蛋白8、嗜铬素A、突触素和促甲状腺激素呈阳性，恶性蝾螈瘤成分（梭形细胞区域）CD56、CD57、钙视网膜蛋白呈阳性，S-100 蛋白、结蛋白和肌细胞生成蛋白呈局灶性阳性。超微结构观察，垂体腺瘤区域胞质中粗面内质网丰富，可见圆形分泌颗粒，梭形细胞胞膜外缘可见不连续基膜。最终病理学诊断为鞍区碰撞瘤（无功能性促甲状腺激素腺瘤合并恶性蝾螈瘤）。患者再次手术后6 个月死亡。结论 垂体腺瘤合并恶性蝾螈瘤的鞍区碰撞瘤极为罕见，术前临床表现和影像学检查难以明确诊断，仍依靠对充分取材的手术标本进行组织学形态、免疫组织化学染色和超微结构观察。含有恶性蝾螈瘤成分的鞍区碰撞瘤预后较差。

关键词: 垂体肿瘤, 腺瘤, 神经鞘肿瘤, 蝶鞍, 病理学, 免疫组织化学