2016 Volume 55 Issue 3 Pages 165-169
Background : The micropapillary variant of urothelial carcinoma (MPUC) is a rare variant of urothelial carcinoma, characterized histopathologically by the presence of tight neoplastic cell clusters with an “inside-out pattern.” Herein, we describe the cytological features of two cases of MPUC of the bladder.
Case ; Case 1 : An 81-year-old male presented with irritable bladder. Cytological examination of a voided urine specimen revealed numerous cohesive papillary clusters without vascular cores. The neoplastic cells had large oval nuclei with coarse chromatin, and some of the cells contained intracytoplasmic vacuoles ; small acinus-like structures were also seen.
Case 2 : A 76-year-old male presented with irritable bladder and hematuria. Cytological examination of a voided urine specimen revealed papillary clusters without vascular cores. The neoplastic cells had large oval nuclei with coarse chromatin, and some of them contained intracytoplasmic vacuoles. Moreover, the neoplastic cell clusters showed an “inside-out pattern” or small acinus-like structures. Immunocytochemical staining for EMA clearly demonstrated the “inside-out pattern.”
Conclusion : The presence of papillary clusters without vascular cores, small acinus-like structures, and intracytoplasmic vacuoles are characteristic features of MPUC. Careful observation for these findings can lead to a cytodiagnosis of MPUC. Moreover, immunocytostaining for EMA is also useful for diagnosing this aggressive variant of urothelial carcinoma.
