Pituicytoma is a rare neoplasm, arising in the posterior pituitary or in the hypophyseal stalk, and its cytological findings have not yet been well-described. We have experienced a case of pituicytoma, which was difficult to diagnose intraoperatively, because of its cellular pleomorphism. A tumor measuring 18 mm in maximum diameter was found at the sella turcica in a Japanese woman in her forties. Both intraoperative crush cytology and histology of the resected tumor showed pleomorphic spindle or round cells, including multinucleated cells. Tumor cells were positive for TTF-1, S-100 protein, and vimentin, partially positive for glial fibrillary acidic protein and epithelial membrane antigen, and negative for synaptophysin, hormones of the anterior pituitary gland, CD34, Olig2, PAX8, and napsin A. Ki-67 labeling index was 2.0%. Tumors included in the differential diagnosis in general are pituitary adenoma, craniopharyngioma, germinoma, and metastatic tumor on the radiological standpoint, and pilocytic astrocytoma and meningioma on the cytological standpoint. However, our case was difficult to differentiate especially from high-grade glioma only by morphology, and immunohistochemistry including TTF-1 was helpful.

中文翻译：

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多形性垂体细胞瘤：附细胞学发现的病例报告

垂体细胞瘤是一种罕见的肿瘤，起源于垂体后叶或垂体柄，其细胞学表现尚未得到很好的描述。我们经历过一例垂体细胞瘤，由于其细胞多形性，术中难以诊断。一名四十多岁的日本女性在蝶鞍处发现了一个最大直径为 18 毫米的肿瘤。切除肿瘤的术中挤压细胞学和组织学均显示多形性梭形或圆形细胞，包括多核细胞。肿瘤细胞TTF-1、S-100蛋白和波形蛋白阳性，胶质纤维酸性蛋白和上皮膜抗原部分阳性，突触素、垂体前叶激素、CD34、Olig2、PAX8和napsin A阴性. Ki-67标记指数为2.0%。一般鉴别诊断包括的肿瘤在放射学上是垂体腺瘤、颅咽管瘤、生殖细胞瘤和转移瘤，在细胞学上是毛细胞星形细胞瘤和脑膜瘤。然而，我们的病例很难仅通过形态学与高级别神经胶质瘤区分，包括 TTF-1 在内的免疫组织化学很有帮助。