Department of Pathology, Inova Fairfax Hospital, Falls Church, Virginia, USA.
Diagn Cytopathol. 2022 Sep;50(9):E248-E254. doi: 10.1002/dc.24975. Epub 2022 May 13.
Plasmacytoid urothelial carcinoma (PUC) is a rare but clinically aggressive variant of high-grade urothelial carcinoma (HGUC). Cytological features include single plasmacytoid neoplastic cells with N:C ratio around 0.5, eccentric nuclei, nuclear hyperchromasia, irregular nuclear membrane, and vacuolated cytoplasm. Micropapillary urothelial carcinoma (MPUC) is another clinically aggressive variant of HGUC that shares some overlapping features of PUC. The diagnosis of these two aggressive variants in pleural effusions can be challenging due to features mimicking adenocarcinoma, unusual immunochemistry profile, and confusion with differential diagnoses, especially when pertinent clinical information is unavailable. We present report on one case each of pleural fluid metastasis of PUC and MPUC respectively, and compare the findings with that of a metastatic conventional HGUC originally thought to be metastatic adenocarcinoma. The diagnosis of PUC was confirmed with immunohistochemical studies showing expression for cytokeratin, GATA-3, uroplakin II, and CD138, diminished or loss of E-cadherin membranous expression, negative expression for p63, p53, Epicam-BerEP4, Epicam-MOC31, and p120. The diagnosis of MPUC was confirmed with immunostain profile similar to that of PUC except positive stain for E-cadherin, p120, and p53. The diagnosis of HGUC was confirmed with immunohistochemical studies showing expression for cytokeratin, GATA-3, uroplakin II, p63, Epicam-BerEP4 (focal weak), and Epicam-MOC31. Our cases of metastatic urothelial carcinoma showed features mimicking adenocarcinoma and others, especially the MPUC and HGUC were diagnosed without prior tissue diagnosis of urothelial carcinoma. This report emphasizes the cytohistological and immunohistochemical details of urothelial carcinoma involving effusion fluid and discusses potential pitfalls in diagnosis.
浆母细胞性尿路上皮癌 (PUC) 是一种罕见但临床上侵袭性很强的高级别尿路上皮癌 (HGUC) 变体。细胞学特征包括具有约 0.5 的 N:C 比的单个浆母细胞性肿瘤细胞、偏心核、核深染、不规则核膜和空泡状细胞质。微乳头状尿路上皮癌 (MPUC) 是另一种具有侵袭性的 HGUC 变体，与 PUC 具有一些重叠特征。由于其特征类似于腺癌、不寻常的免疫组织化学特征以及与鉴别诊断混淆，特别是在缺乏相关临床信息的情况下，在胸腔积液中诊断这两种侵袭性变体具有挑战性。我们分别报告了一例胸腔积液转移的 PUC 和 MPUC，将其与最初认为是转移性腺癌的转移性常规 HGUC 的发现进行了比较。通过免疫组织化学研究证实了 PUC 的诊断，该研究显示细胞角蛋白、GATA-3、尿路上皮蛋白 II 和 CD138 的表达，E-钙黏蛋白膜表达减少或缺失，p63、p53、Epicam-BerEP4、Epicam-MOC31 和 p120 阴性表达。通过免疫组化染色与 PUC 相似但 E-钙黏蛋白、p120 和 p53 阳性表达的特征，证实了 MPUC 的诊断。HGUC 的诊断通过免疫组织化学研究证实，该研究显示细胞角蛋白、GATA-3、尿路上皮蛋白 II、p63、Epicam-BerEP4 (局灶性弱) 和 Epicam-MOC31 的表达。我们的转移性尿路上皮癌病例表现出类似于腺癌和其他肿瘤的特征，尤其是 MPUC 和 HGUC，在没有事先进行尿路上皮癌组织诊断的情况下做出了诊断。本报告强调了涉及胸腔积液的尿路上皮癌的细胞形态学和免疫组织化学细节，并讨论了诊断中的潜在陷阱。
