Cytological Findings of the Micropapillary Variant of Urothelial Carcinoma: A Comparison with Typical High-Grade Urothelial Carcinoma

Abstract

BackgroundMicropapillary variant of urothelial carcinoma (MPUC) showed distinct pathologic features and aggressive behavior. The cytologic findings of MPUC are still indistinct. In this study, we evaluated the cytological findings of MPUC compared with those of high-grade urothelial carcinoma (HGUC).MethodsThe voided urine cytology of 8 cases of MPUC and 8 cases of HGUC was reviewed. Following cytological parameters were evaluated: cellularity, background, number of small, tight papillary clusters, small acinar structure, scattered single cells, cytoplasmic features, nuclear-to-cytoplasmic ratio, nuclear pleomorphism, nuclear membrane irregularity, hyperchromasia, chromatin pattern and nucleoli.ResultsCompared to that of HGUC, cytology of MPUC showed large numbers of small, tight papillary clusters, small acinar structure, few numbers of single cells, and hyperchromatic nuclei. Other parameters were similar between the two groups; both groups showed similar cellularity, dense or vacuolated cytoplasm, moderate to severe nuclear pleomorphism, irregular nuclear membrane, coarse granular chromatin, and small and prominent nucleoli.ConclusionsThe urine cytology of MPUCs showed smaller and tighter papillary cell clusters, more small acinar structures, fewer numbers of scattered single cells, and more hyperchromatic nuclei than that of HGUC. These features can help to distinguish MPUC and HGUC and offer an early cytological diagnosis of MPUC.

A case report of urothelial carcinoma with combined micropapillary and plasmacytoid morphology in the urinary bladder

“…16 Urine cytology specimens usually exhibit micropapillae without fibrovascular cores and an acini-like architecture with scalloped outer contours. 4 In the present case, intraperitoneal spread of disease was present and these tumor cells were histologically Diagnostic Cytopathology DOI 10.1002/dc identified as plasmacytoid UC. 10 Compared to that of typical high-grade UC, the cytology of micropapillary UC shows a large number of small, tight papillary clusters, small acinar structure, fewer isolated cells, and hyperchromatic nuclei.…”

“…The majority of tumors are found to invade muscle at the time of presentation, and lymphovascular invasion is present in more than half of muscle-invading micropapillary UCs. 4 Cytologic features such as cellularity, dense or vacuolated cytoplasm, moderate to severe nuclear pleomorphism, irregular nuclear membranes, coarse granular chromatin, and small and prominent nucleoli are not helpful for distinguishing micropapillary UC from typical high-grade UC. 14 The overall outline of the cell papillae or nests was very irregular and the papillae or nests consisted of highly pleomorphic, atypical cancer cells.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] The micropapillary variant of UC was first reported in 1994. Abdominal computed tomography showed a large enhancing mass on the left lateral and anterior wall of the urinary bladder, which was highly suspicious for extravesicular extension and focal extension of the anterior lesion to the pubic bone.…”

“…To date, only a small number of cytology cases have been reported on either of these variants. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] The micropapillary variant of UC was first reported in 1994. 15 This variant shows a very aggressive pattern of behavior and has a poor prognosis.…”

Diagnostic utility of double immunostaining of a urine cytology preparation for cytokeratin 20/p53 expression in a young woman with micropapillary urothelial carcinoma of the renal pelvis presenting as an unknown primary malignancy

“…Micropapillary UC (MPUC) has an aggressive clinical course with early nodal/distant metastasis, which may alert the clinician. [11] Some investigators have suggested using p63, p40, and GATA-binding protein 3 immunohistochemistry for differentiating MPUC from typical UC. [12]…”