Background. Purely ectopic pituitary adenomas are exceedingly rare. Here we report on a patient that presented with an incidental clival mass thought to be a chordoma. Endonasal resection, tumor pathology, and endocrinology workup revealed a prolactinoma. Case Presentation. A 41-year-old male presented with an incidental clival lesion presumed to be a chordoma. On MRI it involved the entire clivus, extended laterally to the petroclival junction, and invaded the cavernous sinuses bilaterally, encasing both internal carotid arteries, without direct extension into the sella. Intraoperatively, it was clear that the tumor originated from the clivus and that the sellar dura was completely intact. Frozen-section pathology was consistent with a pituitary adenoma. Immunostaining was positive for synaptophysin and prolactin with a low Ki-67 index, suggestive of a prolactinoma. Additional immunohistochemical stains seen in chordomas (EMA, S100, and Brachyury) and other metastatic tumors were negative. A postoperative endocrine workup revealed an elevated serum prolactin of 881.3 ng/mL (normal < 20). Conclusions. In conclusion, it is crucial to maintain an extensive differential diagnosis when evaluating a patient with a clival lesion. Ectopic clival pituitary adenomas, although rare, may warrant an endocrinological workup preoperatively as the majority may respond to medical treatment.
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机译：背景。纯异位垂体腺瘤极为罕见。在这里，我们报道了一名患者，该患者出现了偶发的脊柱肿块，认为是脊索瘤。鼻内切除术，肿瘤病理学和内分泌学检查发现泌乳素瘤。案例介绍。一名41岁的男性出现了偶然的脊柱病变，推测是脊索瘤。在MRI上，它累及整个锁骨，横向延伸到岩斜交界处，并双向侵入海绵窦，包裹了两个颈内动脉，而没有直接延伸到蝶鞍中。术中很明显，肿瘤起源于锁骨，而鞍硬脑膜完全完整。冷冻切片病理与垂体腺瘤一致。突触素和催乳素的免疫染色阳性，Ki-67指数低，提示泌乳素瘤。在脊索瘤（EMA，S100和Brachyury）和其他转移性肿瘤中观察到的其他免疫组化染色均为阴性。术后内分泌检查显示血清催乳素升高至881.3 ng / mL（正常<20）。结论。总之，在评估具有分支病变的患者时，保持广泛的鉴别诊断至关重要。异位性垂体腺瘤虽然很少见，但由于大多数患者可能会对药物治疗产生反应，因此可能需要在术前进行内分泌检查。
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