Original contributionInvasive micropapillary urothelial carcinoma of the bladder☆,☆☆
Introduction
Invasive micropapillary urothelial carcinoma, a rare variant of urothelial carcinoma with histologic appearance similar to micropapillary carcinomas arising in the ovary, lung, breast, or other anatomical locations [1], [2], [3], [4], [5], [6], [7], [8], [9], has been recognized in the current World Health Organization (WHO) classification of urothelial neoplasms and may pose a significant differential diagnostic problem, particularly if it is the predominant or exclusive pattern in a limited biopsy sample [10]. There are limited data available about the pathologic and immunohistochemical characteristics as well as the clinical behavior of this pathologic entity [11], [12], [13], [14], [15], [16], [17], [18], [19], [20]. A reverse cellular polarization, as seen by the MUC1 cellular distribution, seems to be relevant in the pathogenesis of invasive micropapillary carcinomas [15].
Since the initial description by Amin et al [3], more than 100 cases have been reported, mostly as single case report or small sample series [1], [2], [3], [8], [10], [11], [12], [13], [14], [16], [17], [18], [20]. Two recent series of 24 and 12 cases [11], [19], respectively, have addressed the issue of differential diagnosis from secondary invasive micropapillary carcinoma or poorly differentiated conventional urothelial carcinoma with retraction artifact. Samaratunga et al [8], Johansson et al [17], and Kamat et al [13] reported on the clinical significance of micropapillary carcinomas, both superficial and invasive type. These studies concluded that patients have a variable clinical course, with some patients dying rapidly and others experiencing prolonged survival. This probably reflects that the reported series are nonhomogeneous and that the entity is not fully well characterized. [1], [2], [7] Hence, more reports on larger series are needed to elucidate the clinical significance and differential diagnostic implications of this interesting morphologic variant of bladder cancer.
Herein, we present a large sequential series of 13 invasive micropapillary urothelial carcinomas of the bladder supplemented with an extensive immunohistochemical study.
Section snippets
Materials and methods
This study included resection and surgical specimens from 13 patients collected in a series of 2197 (0.6%) bladder tumor specimens studied from 1998 to 2008 at the uropathology practice of one of the authors (A. L. B.). The cases spanned a period of 11 years, with the earliest case diagnosed in 1998 and the last one in 2007. Clinical information was obtained from patients' records, and an average of 16 hematoxylin and eosin slides (range, 7-26 slides) from each case was evaluated. The following
Results
Clinicopathologic features of the 13 patients are summarized in Table 1. In all 13 patients, there was hematuria with dysuria (3 patients) or frequency (4 patients). Their ages ranged from 61 to 83 years (mean, 68 years; median, 63 years). The diagnosis of invasive micropapillary carcinoma of the bladder was made on transurethral resection of bladder (TURB) in 3 cases (53 gr, 55 gr, and 63 gr resection chips, respectively) and TURB followed by cystoprostatectomy or cystectomy with hysterectomy
Discussion
More than 90% of bladder carcinomas are urothelial carcinomas [1], [2]. A small group of tumors is recognized as pathologic variants of invasive bladder cancer due to their unique histologic appearance [1], [2], [7], [10]. These uncommon variant entities are distinct enough to be recognized separately in the current WHO classification system [10]. These variants are significant from the diagnostic, prognostic, and/or therapeutic perspective [1], [2], [3], [4], [5], [6], [7], [8], [9], [11], [12]
References (22)
- et al.
Histologic variants of urothelial carcinoma: differential diagnosis and clinical implications
Hum Pathol
(2006) - et al.
Invasive micropapillary carcinoma of the breast: eight cases of an underrecognized entity
Hum Pathol
(2001) - et al.
Immunohistochemical comparison of MUC1, CA125, and Her2Neu in invasive micropapillary carcinoma of the urinary tract and typical invasive urothelial carcinoma with retraction artefact
Mod Pathol
(2009) Mixed micropapillary and trophoblastic carcinoma of bladder: report of a first case with new immunohistochemical evidence of urothelial origin
Hum Pathol
(2004)- et al.
Pathogenesis of invasive micropapillary carcinoma: role of MUC1 glycoprotein
Mod Pathol
(2004) - et al.
Clinical and pathological characteristics of micropapillary transitional cell carcinoma: a highly aggressive variant
J Urol
(2000) - et al.
Micropapillary bladder carcinoma: a clinicopathological study of 20 cases
J Urol
(1999) - et al.
Muscle-invasive urothelial cell carcinoma of the human bladder: multidirectional differentiation and ability to metastasize
Hum Pathol
(2007) - et al.
Pathological variants of invasive bladder cancer according to their suggested clinical significance
BJU Int
(2008) - et al.
Micropapillary variant of transitional cell carcinoma of the urinary bladder. Histologic pattern resembling ovarian papillary serous carcinoma
Am J Surg Pathol
(1994)
Micropapillary component in lung adenocarcinoma: a distinctive histologic feature with possible prognostic significance
Am J Surg Pathol
Cited by (0)
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No potential conflicts of interest.
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Supported in part by the grant SAF2007-64942, Ministry of Education and Research, Madrid, Spain.