Pleural fluid metastasis of plasmacytoid urothelial carcinoma in comparison to micropapillary and conventional high‐grade urothelial carcinoma: Cytologic and immuonohistochemical findings

Abstract

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 com-

Metastatic upper tract urothelial carcinoma with nest‐like features presenting as malignant pleural effusion

“…The differential diagnosis of NUC is mainly with the micropapillary subtype because small clusters of tumor cells histologically characterize both. At effusion cytology, however, differently from our case, the micropapillary UCa is predominantly arranged in single cells or cell cording, with vacuolated cytoplasm 20 . Furthermore, p63 positivity, as in most NUCs, corroborated the nested subtyping because p63 expression is lost in micropapillary UCa 21,22 …”

“…At effusion cytology, however, differently from our case, the micropapillary UCa is predominantly arranged in single cells or cell cording, with vacuolated cytoplasm. 20 Furthermore, p63 positivity, as in most NUCs, corroborated the nested subtyping because p63 expression is lost in micropapillary UCa. 21,22 Imaging studies of NUC in the bladder describe irregular thickening of the wall without evidence of a defined mass and with extravesical extension.…”

“…To our knowledge, a malignant effusion as a primary manifestation of NUC/UUT has never been described previously. Interestingly, a recent study reported other rare and aggressive variants of UCa, namely micropapillary and plasmacytoid subtypes, in pleural fluid 20 . The differential diagnosis of NUC is mainly with the micropapillary subtype because small clusters of tumor cells histologically characterize both.…”

“…Interestingly, a recent study reported other rare and aggressive variants of UCa, namely micropapillary and plasmacytoid subtypes, in pleural fluid. 20 The differential diagnosis of NUC is mainly with the micropapillary subtype because small clusters of tumor cells histologically characterize both. At effusion cytology, however, differently from our case, the micropapillary UCa is predominantly arranged in single cells or cell cording, with vacuolated cytoplasm.…”