Bosco Martino, Galliano Diego, La Saponara Fedele, Pacchioni Donatella, Bussolati Gianni
Department of Biomedical Sciences and Human Oncology, University of Turin, Italy.
Acta Cytol. 2007 May-Jun;51(3):468-72. doi: 10.1159/000325770.
Metanephric adenoma (MA) is a relatively rare neoplasm derived from metanephric blastema and composed of well-differentiated epithelial nephroblastic cells. In view of its invariably benign clinical outcome, a preoperative diagnosis of this tumor could be of critical importance. Since computed tomography and ultrasound imaging are not per se sufficient to unequivocally distinguish between MA and malignant neoplasms, fine needle aspiration cytology (FNAC) could be the only accurate method to establish a preoperative diagnosis of this tumor. However, cytologic appearance of MA is not well characterized.
A 33-year-old pregnant woman presented with erythrocytosis. Transabdominal ultrasound examination disclosed a mass in her left kidney. FNA smears showed small, uniform cells with bland nuclei arranged in compact acinar and follicular structures; immunocytochemical staining revealed a diffuse, positive reaction for CD57, WT-1 and vimentin, and epithelial membrane antigen and alpha-methylacyl-CoA racemase yielded negative results. These cytologic and immunocytochemicalfindings led to a preoperative diagnosis of MA. After delivery, the diagnosis was confirmed on the surgical specimen.
A diagnosis of MA could be established by FNAC supported by immunocytochemical analysis. The present case illustrates the clinical impact that this diagnosis could have on patient management.
后肾腺瘤（MA）是一种相对罕见的肿瘤，起源于后肾胚基，由分化良好的上皮性肾母细胞组成。鉴于其临床结局始终为良性，术前诊断这种肿瘤可能至关重要。由于计算机断层扫描和超声成像本身不足以明确区分MA与恶性肿瘤，细针穿刺细胞学检查（FNAC）可能是术前诊断该肿瘤的唯一准确方法。然而，MA的细胞学表现特征尚不明确。
一名33岁孕妇出现红细胞增多症。经腹超声检查发现其左肾有一肿块。FNA涂片显示细胞小而均匀，细胞核温和，呈紧密的腺泡状和滤泡状结构排列；免疫细胞化学染色显示CD57、WT-1和波形蛋白呈弥漫性阳性反应，上皮膜抗原和α-甲基酰基辅酶A消旋酶呈阴性结果。这些细胞学和免疫细胞化学结果导致术前诊断为MA。分娩后，手术标本证实了该诊断。
MA的诊断可通过FNAC并结合免疫细胞化学分析来确立。本病例说明了该诊断对患者管理可能产生的临床影响。
