Hasteh Farnaz, Pu Robert, Michael Claire W
Department of Pathology, University of California, San Diego, California, USA.
Diagn Cytopathol. 2007 May;35(5):306-10. doi: 10.1002/dc.20631.
We present clinicopathological and cytological findings of a well-defined breast mass in a patient with history of primary renal carcinoid tumor. Fine-needle aspiration (FNA) cytology showed monotonous tumor cells with plasmacytoid appearance arranged singly and in small clusters. Occasional tumor cells were arranged in acinar architecture resembling glandular differentiation. Tumor cells showed fine speckled chromatin. The unusual location for metastasis of this rare type of carcinoid tumor and overlapping cytological features with primary mammary carcinoma led to an erroneous preliminary cytological diagnosis of primary breast carcinoma with plasmacytoid features. Tumor cells in the corresponding cell block showed strong diffuse positivity for synapthophysin and pan-cytokeratin with weak focal positivity for chromogranin markers. These patterns of immunostaining were similar to the original renal carcinoid tumor. To the best of our knowledge, a few cases of carcinoid tumor metastatic to the breast have been reported in the literature and more than half of these cases were initially misdiagnosed as primary breast carcinoma causing unnecessary surgical treatment. This is a first reported case of metastatic renal carcinoid tumor into breast diagnosed with FNA biopsy. This report highlights the cytological features of well-differentiated neuroendocrine tumor (carcinoid tumor) and its potential diagnostic pitfalls.
我们报告了一例有原发性肾类癌病史患者明确的乳腺肿块的临床病理及细胞学检查结果。细针穿刺（FNA）细胞学检查显示，肿瘤细胞形态单一，呈浆细胞样外观，单个或成小簇排列。偶尔可见肿瘤细胞呈腺泡状结构，类似腺管分化。肿瘤细胞显示细颗粒状染色质。这种罕见类型类癌转移的不寻常部位以及与原发性乳腺癌重叠的细胞学特征，导致最初细胞学误诊为具有浆细胞样特征的原发性乳腺癌。相应细胞块中的肿瘤细胞突触素和全细胞角蛋白呈强弥漫性阳性，嗜铬粒蛋白标记物呈弱局灶性阳性。这些免疫染色模式与原发肾类癌肿瘤相似。据我们所知，文献中已报道了几例转移至乳腺的类癌肿瘤病例，其中一半以上的病例最初被误诊为原发性乳腺癌，导致了不必要的手术治疗。这是首例通过FNA活检诊断为乳腺转移性肾类癌肿瘤的病例。本报告强调了高分化神经内分泌肿瘤（类癌肿瘤）的细胞学特征及其潜在的诊断陷阱。
