Association of urothelial carcinoma of the renal pelvis with papillary and medullary thyroid carcinomas. A new sporadic neoplastic syndrome?

We describe 2 adult women (72 and 54 years), 1 with a low-grade noninvasive papillary urothelial carcinoma of the renal pelvis, who 14 years later developed a papillary carcinoma in 1 thyroid lobe and a medullary carcinoma in the contralateral lobe. Both neoplasms were similar in size and appeared symmetrical. Despite its small size, the medullary carcinoma metastasized in multiple cervical lymph nodes. The second patient had a high-grade invasive papillary urothelial carcinoma of the renal pelvis that infiltrated the renal parenchyma and metastasized in one of the lungs. Five months later, a papillary carcinoma was discovered in the thyroid gland. The 2 papillary thyroid carcinomas were of the follicular variant. Adjacent to 1 papillary carcinoma, there was a dominant nodule of a colloid and adenomatous goiter. The medullary carcinoma contained stromal amyloid and was immunoreactive for calcitonin and carcinoembryonic antigen. There was no C-cell hyperplasia (medullary carcinoma in situ). The 2 patients are alive, 1 is living with pulmonary metastasis from the high-grade urothelial carcinoma. Twelve cases of this neoplastic association were registered in the Survey, Epidemiology, and End Results Program from 1980 to 2009. We believe that the combination of these unusual neoplasms in the same patient may represent a new sporadic neoplastic syndrome.     

Nested variant of urothelial carcinoma of the renal pelvis

The nested variant of urothelial carcinoma is an uncommon form of urothelial carcinoma with distinctive histopathologic features. The majority of cases of this unusual type of urothelial carcinoma have been described in the urinary bladder, with examples of this neoplasm involving the upper urinary tract being extremely limited. The present report details the clinical and pathologic features of an unusual case of a nested variant of urothelial carcinoma occurring in the renal pelvis of a 71-year-old woman. The tumor was characterized by a nested pattern of growth and relatively bland cytologic features, and presented with locally advanced disease at the time of nephroureterectomy. Although rare, awareness that the nested variant of urothelial carcinoma may occur at this particular site is important so as not to confuse this unusual form of urothelial carcinoma with other pathologic lesions of the renal pelvis.     

MET expression in sporadic renal cell carcinomas

Although germline mutations of met proto-oncogene on human chromosome 7q31-34 have been known as useful molecular markers of hereditary papillary renal cell carcinoma (RCC), the expression of MET, a product of met proto-oncogene, has not been fully studied in sporadic RCC, along with its clinical significance. We investigated the expression of MET by immunohistochemistry in 182 cases of renal neoplasm encompassing 145 RCC, 25 urothelial carcinomas of renal pelvis, and 12 oncocytomas. MET was diffusely and strongly expressed in 90% of papillary RCC, all collecting duct carcinomas, and 92% of urothelial carcinomas of renal pelvis. On the contrary, clear cell RCC, chromophobe RCC, and oncocytomas were negative or focally positive for MET expression. In clear cell RCC, MET expression was positively correlated with high nuclear grade, presence of infiltrative growth, tumoral necrosis, papillary architecture, sarcomatoid component, tumoral involvement of the renal pelvis or ureter, involvement of the calyx, and lymphatic invasion. In conclusion, diffuse and strong expression of MET in papillary RCC and collecting duct carcinoma might be helpful in discriminating from the other subtypes of RCC with tubular or papillary growth. In case of MET expression observed in clear cell RCC, it might correlate with those clinicopathological parameters implying aggressive behavior.     

High-grade urothelial carcinoma of the renal pelvis: clinicopathologic study of 108 cases with emphasis on unusual morphologic variants.

A clinicopathologic study of 108 cases of high-grade urothelial carcinomas of the renal pelvis is presented. Of the 108 tumors, 44 (40%) showed unusual morphologic features, including micropapillary areas (four cases), lymphoepithelioma-like carcinoma (two cases), sarcomatoid carcinoma (eight cases, including pseudoangiosarcomatous type), squamous differentiation and squamous cell carcinoma (15 cases), clear cells (two cases), glandular differentiation (two cases), rhabdoid, signet-ring or plasmacytoid cells (four cases), pseudosarcomatous stromal changes (four cases) and intratubular extension into the renal pelvis (three cases). Pathological staging was available in 62 patients; of these, 46 cases (74%) were in high stage (pT2-pT4) and 16 (26%) were in low stage (pTis, pTa, pT1). Clinical follow-up ranging from 1 to 256 months (median: 50 months) was available in 42 patients; of these, 26 (61%) died of tumor with a median survival of 31 months. The patients who did not die of their tumors showed only minimal or focal infiltration of the renal parenchyma by urothelial carcinoma, whereas those who died of their tumors showed massive infiltration of the kidney by the tumor. High-grade urothelial carcinomas of the renal pelvis can show a broad spectrum of histologic features similar to those seen in the urinary bladder. Our results support the finding that, unlike urothelial carcinomas of the bladder, the majority of primary urothelial carcinomas of the renal pelvis are of high histologic grade and present in advanced stages. Our study further highlights the fact that, in the renal pelvis, urothelial carcinomas show a tendency to frequently display unusual morphologic features and metaplastic phenomena. The importance of recognizing these morphologic variants of urothelial carcinoma in the renal pelvis is to avoid confusion with other conditions. The possibility of a high-grade urothelial carcinoma should always be considered in the evaluation of a tumor displaying unusual morphologic features in the renal pelvis, and attention to proper sampling as well as the use of immunohistochemical stains will be of importance to arrive at the correct diagnosis.     

Collecting duct carcinoma: an entity to be redefined?

Collecting duct carcinomas (CDCs) are highly aggressive tumors with poor survival at 1 year and are often metastatic at the time of diagnosis. It has been shown that patients may have better survival when treated with a chemotherapy regimen used for urothelial carcinoma. Such tumors must therefore be recognized, but their pathological diagnosis remains difficult. The two main differential diagnoses are renal pelvis urothelial carcinoma with infiltration of the kidney and/or high-grade and high-stage papillary renal cell carcinoma. The aim of our study was to compare the immunophenotype of 14 CDCs with 6 renal pelvis urothelial carcinomas (RPUC) infiltrating the medulla. The following markers were evaluated: ulex europeus aglutinin (UEA), peanuts aglutinin, vimentin and aquaporin 3 (AQP-3), a membrane component of normal collecting duct and urothelial cells. We were able to define a reproductive urothelial phenotype AQP-3+, vimentin– and UEA+. Among the 14 CDCs, 10 cases demonstrated this immunophenotype. It coincided with an urothelial-like trabecular and tubular pattern. In contrast, the 4 remaining papillary CDCs had the inverse pattern, AQP-3–, vimentin+ and UEA–. These results suggest that: (1) the trabecular and tubular variant of CDC with the urothelial AQP-3+, vimentin– phenotype can be included in the spectrum of urothelial diseases; (2) the papillary variant probably does not belong to the same entity; (3) AQP-3 is a marker of interest for improving the histological classification of CDC and unclassified aggressive renal tumors.     

Microcystic urothelial cell carcinoma with neuroendocrine differentiation arising in renal pelvis. Report of a case

Microcystic urothelial cell carcinoma is a rare variant of urothelial cell carcinoma which occurs in the bladder and, rarely, in the renal pelvis. Neuroendocrine differentiation is uncommon in pure urothelial carcinoma and is more frequently found in neoplasms with glandular differentiation. We report a case of microcystic urothelial cell carcinoma arising in renal pelvis and showing focal neuroendocrine differentiation. A 55-year-old man with a history of non-small cell cancer of the lung presented with abdominal pain and hematuria. Imaging studies and gross examination revealed a partially cystic mass in the left kidney. Microscopic examination disclosed invasive carcinoma with prominent microcystic features, with microcysts lined by low columnar and flat cells. Immunohistochemical analysis confirmed the urothelial histotype (positive for thrombomodulin, p63 and high-molecular-weight cytokeratins) and disclosed focal neuroendocrine differentiation.     

Micropapillary urothelial carcinoma of the upper urinary tract: Clinicopathologic study of five cases

We report 5 cases of micropapillary urothelial carcinoma (MPUC) involving the renal pelvis (2), renal pelvis and ureter (2), and proximal ureter (1). The patients were 2 women and 3 men, ages 65 to 92 years (mean, 76.0 years). All tumors showed a high-grade transitional cell carcinoma component, and in 3 cases, there also were areas of in situ carcinoma. The case involving only the ureter occurred in a 65-year-old man with a history of nephrectomy 12 years previously for urothelial carcinoma of the renal pelvis. The tumor recurred in the ureteral stump. In all cases, areas displaying micropapillary architecture were observed. In 2 cases the micropapillary areas were noninvasive; in 1 case a pure invasive pattern was seen; and in 2 cases a mixed invasive and noninvasive pattern was present. the micropapillary pattern was invasive; and the case involving the ureteral stump contained invasive and noninvasive micropapillary carcinoma. All patients died of their tumors from 3 to 24 months after initial diagnosis. MPUC involving the renal pelvis and ureter is associated closely with advanced stages of disease and has highly aggressive behavior. Recognition of this growth pattern is important for prognosis and avoiding misdiagnosis with papillary renal cell carcinoma and other tumors.     

Expression of carbonic anhydrase IX in genitourinary and adrenal tumours

Donato D P, Johnson M T, Yang X J & Zynger D L
(2011) Histopathology  59 , 1229–1239
Expression of carbonic anhydrase IX in genitourinary and adrenal tumours Aims: High expression of carbonic anhydrase IX (CAIX) is reported for clear cell renal cell carcinoma (RCC), with a paucity of data for non‐renal genitourinary or adrenal tumours. This study investigated the immunohistochemical expression of CAIX throughout the genitourinary tract and adrenal gland. Methods and results: High expression in the renal cortex was restricted to clear cell, papillary and clear cell papillary RCC and carcinoid. Core biopsies of clear cell RCC were consistently positive. Positivity within the urothelial tract was seen in urothelial carcinoma including squamous, small‐cell, sarcomatoid and adenomatous differentiation and clear cell adenocarcinoma. Signet ring and plasmacytoid variants of urothelial carcinoma were negative. Phaeochromocytoma, adrenal cortical adenoma, seminoma, yolk sac tumour, choriocarcinoma, Leydig cell tumour and prostatic adenocarcinoma were predominately negative, with variable reactivity in adrenal cortical carcinoma, embryonal carcinoma, teratoma and Sertoli cell tumour. Conclusions: Carbonic anhydrase IX is a sensitive marker for clear cell RCC in core biopsies. However, other genitourinary or adrenal tumours that can have a clear cell appearance including urothelial, squamous cell, clear cell adeno and adrenal cortical carcinoma and Sertoli cell tumour express CAIX. Knowledge of expression overlap between these entities may prevent incorrect interpretation of immunohistochemical results, particularly if limited tissue is available.     

A cribriform urothelial neoplasm of the renal pelvis: an adenoid cysticlike variant of inverted urothelial papilloma or florid ureteritis cystica?

Tumors with cribriform appearance, similar to that of salivary gland adenoid cystic carcinoma, have been described at various anatomic sites. We present an unusual polypoid tumor, discovered incidentally, in the renal pelvis of an elderly man. The mass displayed a prominent cribriform architecture, akin to adenoid cystic carcinoma with an immunophenotype that supported a urothelial origin. Because of its lack of significant invasive growth and other adverse morphologic features, this lesion will likely behave in a banal fashion. This cribriform urothelial neoplasm of the renal pelvis may, in fact, represent a variant of an inverted urothelial neoplasm with a prominent cystic component or florid ureteritis cystica. It is important for pathologists to recognize this growth pattern as a possible variant of urothelial tumors.     

Synchronous squamous cell carcinoma of the kidney,squamous cell carcinoma of the ureter,and sarcomatoid carcinoma of the urinary bladder: A case report

The author presents a unique case of a synchronous triple carcinoma of kidney, ureter, and urinary bladder. A 73-year-old man was admitted to our hospital because of hematuria and lumbago. Endoscopy and imaging modalities revealed a bladder tumor, a left ureter tumor, and a left kidney tumor. No other tumors were found in the body by imaging modalities. Cystectomy and left nephroureterectomy were performed. The bladder tumor was a large polypoid tumor consisting of pleomorphic sarcomatoid carcinoma (80%) and high-grade papillary urothelial carcinoma (20%), both invading the deep muscle layer. There were gradual merges between the two. The sarcomatous component was composed of malignant spindle, polygonal, and giant cells. Lymphovascular permeation was pronounced. Immunohistochemically, the sarcomatous element was positive for vimentin and various types of cytokeratins (CK), while the urothelial carcinoma element was positive for various types of CK and negative for vimentin. The ureter tumor was small and obstructed the ureter lumen. It was a pure squamous cell carcinoma without a urothelial component. The ureter tumor invaded the adventitia. A mild degree of lymphovascular invasion was recognized. Immunohistochemically, the tumor cells were positive for various types of CK but negative for vimentin. In the kidney, almost the entire kidney parenchyma was replaced by a tumor. The renal pelvis was broadly erosive but was free of apparent tumors. Histologically, the renal tumor was a pure squamous cell carcinoma without a urothelial component. Broad necrosis was present, and lymphovascular permeation was pronounced. The renal pelvis and calices were devoid of apparent tumor cells, but renal squamous cell carcinoma was present just beneath the pelvis and calices. Immunohistochemically, the kidney tumor was positive for various types of CK and negative for vimentin.     

Primary carcinoma of renal calyx

Renal calyx carcinoma (RCXC) may mimic collecting duct carcinoma (CDC) or urothelial carcinoma (UC) of the renal pelvis. RCXC is distinguished from CDC and UC of the renal pelvis as having the tumor epicenter in the renal calyx, with limited involvement of the surrounding renal pelvis surface urothelium. In this study, we summarize our experience with this entity.     

Collecting duct carcinoma of the kidney: an immunohistochemical evaluation of the use of antibodies for differential diagnosis

Collecting duct carcinoma is a highly aggressive renal epithelial malignancy, although it accounts for less than 1% of the incidence of renal epithelial neoplasms. Differential diagnoses between collecting duct carcinoma, pelvic urothelial carcinoma with marked invasion to the renal parenchyma (invasive urothelial carcinoma), and papillary renal cell carcinoma is often challenging. In our current study, we examined the utility of using commercially available antibodies, in conjunction with lectin histochemistry, for such differential diagnoses. We examined 17 cases of collecting duct carcinoma, 10 cases of invasive urothelial carcinoma and 15 cases of papillary renal cell carcinoma (type 1, 6 cases; type 2, 9 cases) in these evaluations. Our results indicated that Ulex europaeus agglutinin 1, E-cadherin, and c-KIT were frequently positive in collecting duct carcinoma and invasive urothelial carcinoma, in comparison with papillary renal cell carcinoma, which had negative results for CD10 and α-methylacyl CoA racemase. We found, however, that collecting duct carcinoma showed positivity for high-molecular-weight cytokeratin and low-molecular-weight cytokeratin at a low frequency compared with invasive urothelial carcinoma, and that these distinctions need further careful evaluation. In addition, high-molecular-weight cytokeratin positivity was not a reliable marker for collecting duct carcinoma. We conclude that Ulex europaeus agglutinin 1 reactivity and positivity for E-cadherin and c-KIT are effective in distinguishing collecting duct carcinoma from papillary renal cell carcinoma, and that negative results for α-methylacyl CoA racemase and CD10 are potentially useful hallmarks of this distinction also. In contrast, a differential diagnosis for collecting duct carcinoma and invasive urothelial carcinoma will require careful examination of multiple routinely stained specimens, particularly in cases of in situ neoplastic lesions in the pelvic mucosa.     

Neoplasms of the upper urinary tract: a review with focus on urothelial carcinoma of the pelvicalyceal system and aspects related to its diagnosis and reporting

Tumors of the renal pelvis account for approximately 7% to 8% of all renal malignancies, greater than 90% of these are of urothelial (transitional cell) origin. These tumors more typically occur in the sixth to eight decade with a slight male preponderance. Varying risk factors for urothelial carcinomas of the upper tract are recognized including environmental and occupational hazards, chemotherapeutic exposure, and previous history of urinary bladder or ureteral carcinomas. Tumor multifocality is frequent and additional tumors may arise in the ureter, bladder, or on the contralateral side. The histopathologic nuances presented by urothelial carcinoma in this region are generally similar to those in the urinary bladder. Though the World Health Organization 2004/International Society of Urological Pathology system used in the bladder is customarily also employed for grading of urothelial tumors of this region, its prognostic significance at this site is not entirely clear as most tumors are treated with nephroureterectomy irrespective of the grade of the tumor. Histologic grade may be an independent prognostic factor in papillary pT1 tumors; however, most pT2 and higher stage tumors tend to be nonpapillary and of higher grade. Despite advances in treatment modalities with sophisticated endoscopic techniques, tumor stage remains the most important prognostic factor. There are several confounding issues related to staging such as the variable presence and thickness of subepithelial connective tissue and muscularis in the renal calyces, renal pelvis, and the ureter; intratubular pagetoid cancer spread (pTis vs. pT3); and assessing invasion in papillary neoplasms with endophytic or inverted growth. Careful gross examination with adequate sampling and understanding the microanatomy of the pelvicalyceal wall are crucial for accurate stage assignment. Poor fixation of large friable tumors and processing artifacts may compound difficulties in accurate staging. This review focuses on urothelial carcinoma of the upper tract highlighting issues related to its diagnosis, staging, and reporting.     

Urothelial carcinoma with rhabdoid features: report of 6 cases

Extrarenal rhabdoid tumors have been described in a variety of primary sites with only rare case reports of urothelial carcinomas with rhabdoid features in the literature. In this report, we describe the clinicopathologic characteristics, including clinical follow-up on 6 cases of urothelial carcinoma with prominent rhabdoid features. Four cases were retrieved from the consultation files of one of the authors and 2 were retrieved from the surgical pathology files at our institution. The patients were all men, with ages ranging from 53 to 86 years (mean, 66.5 years). Patients initially presented with hematuria or obstructive symptoms. The sites included bladder (n = 4) and renal pelvis (n = 2). All cases had a prominent rhabdoid component (mean, 60%), ranging from 40% to 80%. In addition to the rhabdoid component, multiple coexistent histological components were seen, including in situ urothelial carcinoma (carcinoma in situ) and high-grade papillary urothelial carcinoma (n = 2), poorly differentiated carcinoma with small-cell features (n = 1), sarcomatoid (n = 2), and a myxoid component (n = 2). All cases in this series had focal or diffuse positive staining with one or more cytokeratin markers (epithelial membrane antigen, CAM 5.2, AE1/AE3). Of the 6 patients, 4 were treated initially with surgery (radical cystoprostatectomy, n = 2; radical nephrectomy, n = 2). Of 6 patients, 2 died within 1 month, whereas a third patient died within 4 months. The remaining 3 patients were alive at 3, 3, and 9 months after diagnosis. The histological and immunohistochemical findings in this study serve to broaden the morphological spectrum of urothelial carcinomas with prominent rhabdoid features and add further evidence as to their poor prognosis.     

Multiple cytokeratin-negative malignant tumors composed only of rhabdoid cells in the renal pelvis: a sarcomatoid urothelial carcinoma?

The author presents a unique case of multiple cytokeratin-negative malignant tumors consisting only of rhabdoid cells in the renal pelvis. A 54-year-old man complained of hematuria. A transurethral endoscopic examination revealed multiple papillary tumors, and transurethral resection of the bladder tumors was performed. Pathologically, they were ordinary papillary urothelial transitional cell carcinomas. Imaging modalities revealed multiple tumors of the right renal pelvis, and nephrectomy was performed. Grossly, three polypoid tumors measuring 2-4 cm were present in the pelvis. Histologically, they were composed only of malignant cells with rhabdoid features. There were no elements of transitional cell carcinoma. Immunohistochemically, the pelvic tumors were positive for vimentin and Ki-67 antigen (labeling=40%). They were negative for pancytokeratins (AE1/3, CAM5.2, KL-1 and polyclonal wide), 34βE12, cytokeratin (CK) 5/6, CK7, CK8, CK14, CK18, CK19, CK20, melanosome, EMA, CEA, desmin, S100 protein, α-smooth muscle actin, myoglobin, myogenin, CD34, p53 protein, p63, CD3, CD20, CD30, CD45, CD45RO, chromograin, synaptophysin, CD56, CD68, and KIT. NSE and PDGFRA were focally present, but this appeared nonspecific. Namely, the pelvic tumors expressed only vimentin. The author speculates that the pelvic multiple malignant “rhabdoid” tumors are not sarcomas but urothelial “rhabdoid” carcinoma with complete loss of CKs.     

Papillary tumour of the vagina resembling transitional cell carcinoma

A case of a peculiar papillary neoplasia of the vagina resembling a urothelial tumour is presented. Four vaginal tumours were excised from a 76-year-old woman. Five years before this patient had undergone a uretero-nephrectomy for a non-invasive papillary transitional cell carcinoma of the renal pelvis. The four vaginal tumours demonstrated gross and microscopic similarities to low-grade papillary transitional cell carcinoma of the urinary tract. This observation indicates that multicentric, non-invasive, papillary tumours may affect the whole uro-genital area. The vaginal wall was not overlaid by a normal squamous epithelium, but by a peculiar "transitional-like" epithelium. Variegated endocrine cells were documented within this lining, using immunohistochemical and ultrastructural techniques. The eventuality of a histogenetic link between the tumour and the adjacent epithelial lining remains unresolved.     

Needle aspiration cytology of low-grade transitional cell carcinoma of the renal pelvis

Five cases of histologically confirmed grade 1 papillary transitional cell carcinoma of the renal pelvis investigated by needle aspiration biopsy cytology were reviewed. In all cases the needle aspirates were hypercellular. Abundant benign-appearing urothelial cells in thick clusters, in small aggregates, and singly were seen in two cases. Numerous single and loosely aggregated urothelial cells with cytoplasmic extensions and slightly pleomorphic nuclei were noted in one case. In two patients numerous urothelial fragments of variable sizes showing defined cytoplasm and mildly nuclear pleomorphism were the main cellular findings. Diagn. Cytopathol. 16:437–441, 1997. © 1997 Wiley-Liss, Inc.     

Rectal adenocarcinoma with choriocarcinomatous differentiation: clinical and genetic aspects

Nongestational choriocarcinomas are rare tumors. In the gastrointestinal tract, they are characterized by a biphasic tumor growth with separated areas of adenocarcinomatous and choriocarcinomatous differentiation. We here report a case of a combined adenocarcinoma-choriocarcinoma of the rectum. The tumor showed an aggressive clinical behavior with metastasis to the liver and lungs. A transient partial remission was achieved after 4 cycles of cisplatinum, etoposide, and ifosfamide chemotherapy, with normalization of serum β-human chorionic gonadotropin levels. At this time, viable residual choriocarcinoma cells were found in surgically resected lung metastasis. The patient succumbed 8 months after initial diagnosis to a rapid abdominal relapse. We used comparative genomic hybridization (CGH) and fluorescence in situ hybridization to elucidate the genetic relationship of adenocarcinoma and choriocarcinoma in this neoplasm. We found genetic changes characteristic for colorectal adenocarcinomas, a loss of chromosomal regions 8p21-pter as well as 18q21-pter, and a gain of 5p and 20q, in both tumor parts. This provides evidence for the common origin of both components. A differential pattern of additional genetic changes suggests a clonal evolution from a common ancestor cell. In contrast to findings from a comparative study on a choriocarcinoma of the renal pelvis, we did not find an amplification of the germ cell cancer-associated chromosomal region 12p11.2-p12.1 in the areas of choriocarcinoma but found instead a loss of Xp11.3-pter. To our knowledge, this is the first report of a CGH comparision of the adenocarcinomatous and choriocarcinomatous tumor parts in a nongestational choriocarcinoma of the gastrointestinal tract.     

Microcystic transitional cell carcinoma: a report of 2 cases arising in the renal pelvis

Microcystic transitional cell carcinoma is a rare variant of urothelial carcinoma; to date, it has been described only in the urinary bladder. We report 2 cases of microcystic transitional cell carcinoma arising in the renal pelvis. The first case occurred in a 73-year-old man with a history of superficially invasive transitional cell carcinoma who presented with macroscopic hematuria and anemia. The second case occurred in a 62-year-old woman who had no relevant medical history and presented with hematuria. Computed tomographic scan revealed a tumor of the renal pelvis. In both cases, microscopic examination showed invasive transitional cell carcinoma with prominent cystic features. The cysts were irregular in size and were deeply infiltrative. The cysts were lined by single or multiple layers of cuboidal or flattened cells with minimal cytological atypia. The first patient died of his disease 18 months after presentation. The second patient remained well at her 6-month follow-up examination. Microcystic transitional cell carcinoma is an unusual, deceptively bland variant of urothelial carcinoma, which can mimic benign lesions.     

Undifferentiated carcinoma of the renal pelvis with osteoclast‐like giant cells: a report of two cases

McCash SI, Unger P, Dillon R, Xiao G‐Q. Undifferentiated carcinoma of the renal pelvis with osteoclast‐like giant cells: a report of two cases. APMIS 2010; 118: 407–12. Undifferentiated carcinoma with osteoclast‐like giant cells arising in the urothelium of the bladder or upper urinary tract is an extremely rare entity. The majority of cases found in the renal pelvis and bladder are associated with either an in situ urothelial malignancy or a conventional high‐grade urothelial carcinoma. These malignancies tend to behave poorly with a grim prognosis and course. We report two additional cases of undifferentiated carcinoma with osteoclast‐like giant cells of the renal pelvis in two patients disease free 42 and 18 months after surgical treatment, respectively.