Cerebrospinal fluid (CSF) evaluation for total and differential cell count is a common practice in pathology for evaluation of various disease conditions. Although rare, these CSF samples yield interesting and unusual morphological findings, which are not only of academic interest, but also may play key roles in diagnosis. For diagnosing metastatic carcinoma in brain and meninges, CSF examination is one of the important tools along with imaging studies. Metaplastic breast carcinoma (MBC) encompasses a rare (<1% of all breast cancers), aggressive and highly heterogeneous group of tumors. MBC is almost always estrogen receptor, progesterone receptor and Her2 negative (triple negative) and shows frequent early distant metastases as well as sub‐optimal response to systemic therapies. The involvement of leptomeninges is most commonly associated with these triple‐ negative subtypes. In this report, we present an unusual case of malignant cells with prominent intracytoplasmic granules in CSF smears of a 46‐year‐old female with metastatic MBC with acinar differentiation. An extensive review of literature in English language did not return any other reports of a similar finding.

中文翻译：

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伴有腺泡分化的乳腺化生性癌脑脊液中异常的胞浆内颗粒发现

脑脊液 (CSF) 总细胞计数和分类细胞计数评估是病理学评估各种疾病状况的常见做法。虽然罕见，但这些 CSF 样本产生了有趣且不寻常的形态学发现，这些发现不仅具有学术意义，而且可能在诊断中发挥关键作用。对于诊断脑和脑膜转移癌，脑脊液检查与影像学研究一起是重要的工具之一。化生性乳腺癌 (MBC) 包括一种罕见的（<所有乳腺癌的 1%）、侵袭性和高度异质性的肿瘤组。MBC 几乎总是雌激素受体、孕激素受体和 Her2 阴性（三阴性），并且表现出频繁的早期远处转移以及对全身治疗的次优反应。软脑膜受累最常与这些三阴性亚型相关。在本报告中，我们介绍了一例罕见的恶性细胞病例，该病例在一名 46 岁女性的 CSF 涂片中具有明显的胞质内颗粒，该女性患有转移性 MBC 并伴有腺泡分化。对英语文献的广泛审查没有返回任何其他类似发现的报告。