Cyto-histo correlations of plasmacytoid and micropapillary variants of high-grade urothelial carcinoma: do they fit well in The Paris System for reporting urinary cytology?

INTRODUCTION: Plasmacytoid and micropapillary variants of high-grade urothelial carcinoma (HGUC) exhibit unique histologic morphology and very aggressive clinical behavior. However, the morphology of these 2 variants in urinary cytology is not well studied and evaluated using The Paris System for reporting urinary cytology. MATERIALS AND METHODS: A database search was performed in all patients with the diagnosis of plasmacytoid or micropapillary HGUC. A total of 5 patients with positive urinary cytology cases were identified. The cytomorphology of every urinary cytology case was correlated with the histologic features in the surgical specimens from the same patient. RESULTS: One urine and 4 bladder washings were evaluated. Cytologically, plasmacytoid HGUCs are characterized by single, large tumor cells with hyperchromasia, irregular nuclear membranes, and vacuolated cytoplasm. The nuclear-to-cytoplasmic (N:C) ratio was less than 0.5 in many of the malignant cells due to the abundant cytoplasm. The cytology features of micropapillary HGUC include the presence of micropapillae of tumor cells with no fibrovascular core. Individual high-grade urothelial cells were also identified in all 4 cases, but 1 (25%) of these had only rare cells meeting The Paris System criteria for HGUC due to abundant cytoplasm and lack of hyperchromasia in most malignant cells. CONCLUSIONS: Plasmacytoid and micropapillary variants of HGUC have unique cytomorphologic features in urinary cytology specimens, which are reflective of the corresponding histological findings. These 2 clinically aggressive variants of HGUC may not be as readily interpreted as malignant using The Paris System for reporting urinary cytology, creating potential diagnostic pitfalls.

iTRAQ analysis of urinary proteins: Potential use of gelsolin and osteopontin to distinguish benign thyroid goiter from papillary thyroid carcinoma.

BACKGROUND: Benign thyroid goiter (BTG) and papillary thyroid carcinoma (PTC) are often interchangeably misdiagnosed. METHODS: Pooled urine samples of patients with BTG (n=10), patients with PTC (n=9) and healthy controls (n=10) were subjected to iTRAQ analysis and immunoblotting. RESULTS: The ITRAQ analysis of the urine samples detected 646 proteins, 18 of which showed significant altered levels (p<0.01; fold-change>1.5) between patients and controls. Whilst four urinary proteins were commonly altered in both BTG and PTC patients, 14 were unique to either BTG or PTC. Amongst these, four proteins were further chosen for validation using immunoblotting, and the enhanced levels of osteopontin in BTG patients and increased levels of a truncated gelsolin fragment in PTC patients, relative to controls, appeared to corroborate the findings of the iTRAQ analysis. CONCLUSION: The data of the present study is suggestive of the potential application of urinary osteopontin and gelsolin to discriminate patients with BTG from those with PTC non-invasively. However, this needs to be further validated in studies of individual urine samples.

High Urinary Iodine, Thyroid Autoantibodies, and Thyroid-Stimulating Hormone for Papillary Thyroid Cancer Risk.

Thyroid nodules have become a common clinical problem, and the clinical importance of thyroid nodules lies in the determination of thyroid cancer. This study aims to evaluate the risk factors for papillary thyroid cancer (PTC) with regard to urinary iodine concentration (UIC), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TGAb) in comparison to thyroid nodular goiter (NG). Among the 2041 patients, 43.8% of which showed more than adequate (UIC 200-299 µg/L) and excessive iodine (UIC ≥ 300.0 µg/L) status. Compared with adequate iodine intake, iodine deficiency (UIC < 100 µg/L) was inversely associated with multifocality (OR 0.59, P = 0.040), while more than adequate iodine intake was independently associated with an increased risk of larger tumor size (OR 1.33, P = 0.002) in female PTC patients but not in males. No significant difference in UIC was observed between patients with PTC and NG, suggesting that high iodine intake may be related with the growth of PTC, but not with its oncogenesis. Besides, positive for TPOAb and TGAb were individually associated with papillary thyroid microcarcinoma (PTMC) risk (OR 2.05 and 1.71, respectively, both P < 0.05) in female patients with tumor foci < 1 cm but not in males. Furthermore, younger age (< 46 years), TGAb positivity and small thyroid nodules in both sexes, higher TSH, TPOAb positivity, and multifocality in females could all predict PTC risk (all P < 0.05). These results might have clinical significance for managing patients with thyroid nodules and those with thyroidectomy.

Higher urinary bisphenol A concentration and excessive iodine intake are associated with nodular goiter and papillary thyroid carcinoma.

In the present study, we investigated whether bisphenol A (BPA) levels and excessive iodine intake were associated with papillary thyroid carcinoma (PTC) and nodular goiter (NG). We determined total BPA concentrations (TBC) in paired serum and urine samples, and urinary iodine concentrations (UIC) in urine samples collected from PTC patients, NG patients, and healthy individuals, then compared BPA concentrations and UIC within and between each patient group. The results showed that there were no gender-specific differences in serum TBC and UIC in each group, and no differences across all patient groups. Urinary BPA concentrations (UBC) were higher in the NG and PTC groups compared with the control group. UBC showed gender-specific differences in the NG and PTC group. Furthermore, UIC were higher in the NG and PTC groups compared with the control group. Higher UBC and excessive iodine intake were risk factors for NG and PTC according to multivariate logistic regression analysis. There was a significant correlation between UBC and UIC in each group. These data suggested that higher UBC and excessive iodine intake are associated with NG and PTC. The metabolic and functional pathways between BPA and iodine are potentially linked to the pathogenesis and progression of NG and PTC.

Diagnostic value of neutrophil gelatinase-associated lipocalin/matrix metalloproteinase-9 pathway in transitional cell carcinoma of the bladder.

Neutrophil gelatinase-associated lipocalin (NGAL), matrix metalloproteinase (MMP)-9, and NGAL/MMP-9 complex have been evaluated as diagnostic markers of several cancers, but results for bladder cancer are scanty. We evaluated these proteins in urine and serum of 89 patients with histologically confirmed bladder cancer and 119 cancer-free controls from a case-control study. Urinary concentrations were standardized on creatinine level. The performance of these proteins as cancer biomarkers was evaluated through the receiver operating characteristic (ROC) analysis. Urinary level of NGAL, MMP-9, and NGAL/MMP-9 complex was higher in current smokers, whereas no impact of dietary habits was observed. After adjusting for tobacco smoking, urinary concentration of MMP-9 was independently associated with cancer invasiveness, grading, and histological subtype, with elevated concentrations among T2-T4 and non-papillary bladder cancers. Conversely, NGAL and NGAL/MMP-9 complex were significantly higher in non-papillary than in papillary subtype. The pattern was less clear in serum, but correlation between urinary and serum concentration was poor, especially for Ta/is-T1 tumors. The ROC analysis confirmed that MMP-9 was the best marker (area under the ROC curve (AUC) = 0.68). Performances were much greater for muscle-invasive bladder cancers (AUC = 0.90), with elevated negative predictive values (97 %). The present study suggests that NGAL/MMP-9 pathway is associated with an aggressive phenotype of bladder cancer. The elevated negative predictive value of MMP-9 and NGAL/MMP-9 complex makes them candidate markers of exclusion test for bladder cancer. These proteins may be integrated in the surveillance of bladder cancer, thus diminishing patients' discomfort and improving compliance.

Cytomorphological characteristics of low-grade papillary urothelial carcinoma for differential diagnosis from benign papillary urothelial lesions: logistic regression analysis in SurePath(™) liquid-based voided urine cytology.

OBJECTIVE: The diagnosis of low-grade papillary urothelial carcinoma (LGPUC) in urine cytology specimens is challenging because of its subtle, minimally atypical findings. Furthermore, as SurePath(™) liquid-based cytology (LBC) is becoming a widely used method in urine cytology, the inevitable cytomorphological alterations resulting from this technique call for new morphological diagnostic criteria in LGPUC. METHODS: Logistic regression analysis was carried out on SurePath slides from surgically proven voided urine specimens. The study was designed to include a test set (n = 141) and a validation set (n = 61), and evaluated significant discriminative parameters between LGPUC and benign papillary urothelial neoplasm (BPUN). RESULTS: Of the seven cytological findings that were found to have statistical significance in univariate analysis, five were found to be independent variables: loss of polarity of papillaroid clusters, irregular contours, absence of columnar cells, hobnail features and hyperchromasia. These independent variables had an area under the curve (AUC) of 0.781. CONCLUSIONS: The distinctive cytological criteria identified above may prove to be helpful in cases in which other conventional criteria for LGPUC are insufficient for diagnosis.

Benign-appearing urothelial tissue fragments in noninstrumented voided urine specimens are associated with low rates of urothelial neoplasia.

BACKGROUND: The presence of urothelial tissue fragments (UTF) in voided urine (VU) is often considered an abnormal finding that may be associated with the presence of urothelial papillary neoplasms. In the current study, the authors reviewed VU specimens containing benign-appearing UTF (BUTF) to determine the associated rate of urothelial neoplasia at the study institution. METHODS: A retrospective search of the electronic pathology database system over a 5-year period (2009-2013) revealed 1131 VU specimens containing UTF. Of these, 459 cases (40.6%) did not have a recent history of instrumentation. Fifteen cases were excluded because the slides were not available for review. In the remaining 444 cases, 274 cases (61.7%) had BUTF. A total of 170 cases (38.3%) had UTF with atypical cytologic features and were therefore excluded. RESULTS: Of the 274 cases, 29 (10.6%) had follow-up surgical pathology specimens available. The overall rate of urothelial neoplasia on follow-up was 3.6% for low-grade urothelial neoplasia (10 cases) and 0.7% for high-grade urothelial carcinoma (2 cases). Forty-five cases (16.4%) were determined to have urinary tract stones on follow-up. CONCLUSIONS: The presence of BUTF in VU specimens requires careful examination of the medical history because their presence may be explained by recent instrumentation. If recent instrumentation is not identified, the etiology of BUTF is not usually determined; in the current study, BUTF were found to be associated with urinary tract stones in 16.4% of cases. They also present a low risk of low-grade urothelial neoplasia (3.6%) and high-grade urothelial carcinoma (0.7%) when compared with the overall benign category at the study institution (2.3% [P =.15] and 0.7%, respectively).

Discrepant serum and urine ß-hCG results due to production of ß-hCG by a cribriform-morular variant of thyroid papillary carcinoma.

BACKGROUND: Although patients with medullary thyroid cancer are known to present with paraneoplastic hormone production, this is much less common with papillary thyroid cancer. METHODS: We present a patient with the cribriform morular variant of papillary thyroid cancer in association with familial adenomatous polyposis who developed a positive pregnancy test in the absence of known pregnancy. The patient had developed vaginal bleeding, and her laboratory testing was characterized by elevated serum human chorionic gonadotropin (ß-hCG) concentrations, but negative qualitative urine results. After a thorough gynecological evaluation to exclude unexpected normal, ectopic, or molar pregnancy, we pursued an evaluation for other sources of ß-hCG production. RESULTS: We showed that the elevated serum ß-hCG concentrations were not the result of heterophile antibody interferences, and ultimately we proved that her recurrent tumor produced the ectopic ß-hCG. This is the first report of ß-hCG production by papillary thyroid cancer. Thus, the possibility of ectopic production of ß-hCG by papillary thyroid cancer needs to be included in the differential diagnosis of elevated hCG concentration in the absence of pregnancy. CONCLUSIONS: This study of an unusual paraneoplastic syndrome highlights the importance of investigating discrepancies in the clinical laboratory.

Strong association of high urinary iodine with thyroid nodule and papillary thyroid cancer.

This study demonstrates a strong association of high urinary iodine with thyroid nodules and papillary thyroid cancer as well as aggressive cancer features, suggesting that high urinary iodine is a risk factor for thyroid cancer. The risk of high iodine intake for thyroid cancer has been suggested but not established. The objective of the study was to evaluate the relationship between urine iodine levels and thyroid nodule and thyroid cancer. We preoperatively tested fasting urine iodine in 154 thyroid nodule patients and correlated the results with pathological diagnoses and compared with 306 subjects as normal control. The median urine iodine (MUI) was 331.33 µg/L in patients with benign thyroid nodules versus 466.23 µg/L in patients with papillary thyroid cancer (PTC) (P=0.003), both of which were in the excessive iodine state and higher than the MUI of 174.30 µg/L in the control group (P < 0.001), which was in the sufficient iodine state. Excessive iodine state (MUI>300 µg/L) was seen in 62.75% of patients with benign thyroid nodules and 66.99% of patients with PTC, both of which were significantly higher than the iodine excessive rate of 19.93% in the control group (P<0.001). Moreover, MUI in patients with PTC with lymph node metastasis was significantly higher than that of PTC patients without lymph node metastasis (P<0.001). Urine iodine of thyroid cancer patients with stage III and IV disease was significantly higher than that of patients with stage I and II diseases (P<0.001). Multivariable analyses showed that, like sand calcification of thyroid nodule and TSH, urine iodine was an independent risk factor for PTC. These data demonstrate a significant association between high urinary iodine and benign and malignant thyroid nodules and PTC aggressiveness, supporting high urinary iodine as a risk factor for thyroid malignancy. Further studies are warranted to confirm these findings.

Association between excessive urinary iodine excretion and failure of radioactive iodine thyroid ablation in patients with papillary thyroid cancer.

BACKGROUND: A low-iodine diet (LID) is usually recommended for a week or two before radioactive iodine (RAI) ablation therapy in papillary thyroid cancer (PTC) patients after total thyroidectomy. However, it is still controversial whether an LID affects ablation outcomes. We therefore evaluated the association between urinary iodine excretion and the rate of successful ablation and investigated the determinants of successful RAI ablation outcomes. METHODS: We retrospectively reviewed the records of 295 consecutive patients with PTC who received 1110 MBq RAI remnant ablation therapy with thyroid hormone withdrawal after total thyroidectomy. Successful ablation was defined as either no visible or faint uptake on a follow-up scan (definition 1), or no visible or faint uptake on a follow-up scan and a stimulated thyroglobulin level <2 ng/mL (definition 2). RESULTS: The proportion of patients with appropriate LID status (defined as a urinary iodine concentration [UIC] <66.2 µg iodine/g creatinine [µg/gCr]) was significantly higher in the successfully ablated group (81% vs. 67%, p=0.03). Based on definition 1, 80.3% (237/295) of patients were successfully ablated. The ablation rate was significantly lower in patients who had a UIC >250 µg/gCr at the time of RAI ablation (p<0.05). In multivariate analysis, a UIC >250 µg/gCr was the only significant variable associated with ablation failure (p=0.002, odds ratio [OR] 4.74 [95% confidence interval (CI) 1.78-12.63]). Based on definition 2, 74.9% (221/295) of patients were successfully ablated. A UIC >250 µg/gCr at RAI administration showed a significant association with ablation failure (p<0.05). The OR of a UIC >250 µg/gCr for ablation failure was 3.88 [CI 1.42-10.57] (p=0.008). CONCLUSION: Excessive iodine intake (UIC >250 µg/gCr) was associated with poor RAI ablation outcomes. Because this amount of iodine is very high, we propose that the level of strictness of the LID protocol should be modified according to the region that the patient is from and the food that the patient is accustomed to eating. Even in those areas where iodine intake is high, overly strict compliance with an LID protocol is not necessary and simple recommendations to avoid iodine-rich foods would be appropriate.

Metabolic alteration of urinary steroids in pre- and post-menopausal women, and men with papillary thyroid carcinoma.

BACKGROUND: To evaluate the metabolic changes in urinary steroids in pre- and post-menopausal women and men with papillary thyroid carcinoma (PTC). METHODS: Quantitative steroid profiling combined with gas chromatography-mass spectrometry was used to measure the urinary concentrations of 84 steroids in both pre- (n = 21, age: 36.95 ± 7.19 yr) and post-menopausal female (n = 19, age: 52.79 ± 7.66 yr), and male (n = 16, age: 41.88 ± 8.48 yr) patients with PTC. After comparing the quantitative data of the patients with their corresponding controls (pre-menopause women: n = 24, age: 33.21 ± 10.48 yr, post-menopause women: n = 16, age: 49.67 ± 8.94 yr, male: n = 20, age: 42.75 ± 4.22 yr), the levels of steroids in the patients were normalized to the mean concentration of the controls to exclude gender and menopausal variations. RESULTS: Many urinary steroids were up-regulated in all PTC patients compared to the controls. Among them, the levels of three active androgens, androstenedione, androstenediol and 16α-hydroxy DHEA, were significantly higher in the pre-menopausal women and men with PTC. The corticoid levels were increased slightly in the PTC men, while progestins were not altered in the post-menopausal PTC women. Estrogens were up-regulated in all PTC patients but 2-hydroxyestrone and 2-hydroxy-17ß-estradiol were remarkably changed in both pre-menopausal women and men with PTC. For both menopausal and gender differences, the 2-hydroxylation, 4-hydroxylation, 2-methoxylation, and 4-methoxylation of estrogens and 16α-hydroxylation of DHEA were differentiated between pre- and post-menopausal PTC women (P < 0.001). In particular, the metabolic ratio of 2-hydroxyestrone to 2-hydroxy-17ß-estradiol, which could reveal the enzyme activity of 17ß-hydroxysteroid dehydrogenase, showed gender differences in PTC patients (P < 1 × 10-7). CONCLUSIONS: These results are expected be helpful for better understanding the pathogenic differences in PTC according to gender and menopausal conditions.

Urinary biomarkers for the early diagnosis of kidney cancer.

OBJECTIVE: To test the hypothesis that increased tumor expression of proteins such as aquaporin-1 (AQP1) and adipophilin (ADFP) in patients with renal cancer would result in increased urine AQP1 and ADFP excretion. PATIENTS AND METHODS: Prenephrectomy and postnephrectomy (pseudocontrol) urine samples were collected from 42 patients with an incidental radiographically discovered renal mass and presurgical presumptive diagnosis of kidney cancer from July 8, 2008, through March 10, 2009. Also enrolled were 15 control patients who underwent nonrenal surgery and 19 healthy volunteers. Urine AQP1 and ADFP concentrations normalized to urine creatinine were determined by sensitive and specific Western blot assays. RESULTS: Mean +/- SD preexcision urine AQP1 and ADFP concentrations (76+/-29 and 117+/-74 arbitrary units, respectively) in patients with a pathologic diagnosis of clear cell (n=22) or papillary (n=10) cancer were significantly greater than in patients with renal cancer of nonproximal tubule origin, control surgical patients, and healthy volunteers (combined values of 0.1+/-0.1 and 1.0+/-1.6 arbitrary units, respectively; n=44; P<.001). The AQP1 and ADFP concentrations decreased 88% to 97% in the 25 patients with clear cell or papillary cancer who provided postnephrectomy follow-up urine samples. In patients with clear cell and papillary carcinoma, a linear correlation (Spearman) was found between tumor size and preexcision urine AQP1 or ADFP concentration (r=0.82 and 0.76, respectively; P<.001 for each). CONCLUSION: Urine AQP1 and ADFP concentrations appear to be sensitive and specific biomarkers of kidney cancers of proximal tubule origin. These biomarkers may be useful to diagnose an imaged renal mass and screen for kidney cancer at an early stage. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00851994.

A hormonal association between estrogen metabolism and proliferative thyroid disease.

OBJECTIVE: To illustrate a relationship between proliferative thyroid disease and estrogen metabolism through the analysis of urinary estrogen metabolites. STUDY DESIGN AND SETTING: Case-control study of 49 subjects with proliferative thyroid disorders and matching them to 49 controls. Urinary estrogen metabolite ratios were obtained, measuring 2-hydroxyestrone, an anti-proliferative metabolite, to 16alpha-hydroxyestrone, a proliferative metabolite. The patients were stratified into low (0 to 1.00), medium (1.01 to 2.00), or high (>2.00) groups according to their estrogen metabolite ratio. RESULTS: Fifty-one percent (25 of 49) of the cases had a low 2/16 ratio compared to 31% (15 of 49) in the control group while 20% (10 of 49) of the control group had a high 2/16 ratio as compared to 8% (4 of 49) in the case group (P value < 0.05). CONCLUSIONS: Increased 16alpha-hydroxyestrone activity compared to 2-hydroxyestrone activity appears to be associated with proliferative thyroid disease. SIGNIFICANCE: Further study of estrogen metabolites in relation to proliferative thyroid disease is warranted and may lead to implications for new treatment modalities for proliferative thyroid disease. EBM RATING: B-3b.

Unusual cytologic findings in low grade papillary transitional cell carcinoma.

OBJECTIVE: To describe cases of low grade papillary transitional cell carcinoma (LG-pTCC) with a low nuclear cytoplasmic (N/C) ratio and unusual cytologic patterns with many isolated, single neoplastic cells. STUDY DESIGN: We defined the following unusual cytologic findings as "isolated, single cell pattern": (1) numerous single cells sometimes with a few flat cell clusters; (2) very low N/C ratio; (3) angulation of cytoplasmic contour; (4) pale, homogeneous cytoplasm; (5) hyperchromatic nuclei with an uneven contour; (6) monotonous cytologic appearance; and (7) clear background. We studied 2,956 cytologic specimens of voided urine from 114 LG-pTCC patients at our university hospital during a 10-year period. RESULTS: Thirty-six specimens had the isolated, single cell pattern. The isolated, single cell pattern showed less celllular atypia than does the typical pattern of LG-pTCC. On histology the cases with the isolated, single cell pattern showed a papillary structure with an erosive surface and were composed of mildly atypical neoplastic cells with very low N/C ratios. CONCLUSION: Some LG-pTCCs show many single, atypical transitional cells.

Cytologic diagnosis of low-grade papillary urothelial neoplasms (low malignant potential and low-grade carcinoma) in the context of the 1998 WHO/ISUP classification.

The 1998 World Health Organization/International Society of Urological Pathology (WHO/ISUP) classification of urothelial neoplasms introduced a category called papillary neoplasm of low malignant potential (LMP) and separated it from low-grade papillary urothelial carcinoma (LGPUC), which was thought to yield abnormal cells in cytology specimens. The objective of our study was to evaluate the effectiveness of urine cytology in diagnosing these lesions. Eighty-six paired transurethral surgical biopsy and corresponding urine cytology specimens representing the spectrum of urothelial papillary lesions were examined. Consensus diagnosis on each biopsy was made, and the distribution was as follows: 16 benign urothelium, 27 LMP, 28 LGPUC, and 15 high-grade papillary urothelial carcinoma (HGPUC). This was followed by a blinded independent review of the urine cytology specimens by three observers. Each cytology case was marked as negative, atypical, suspicious, or positive for malignant cells by using previously published cytologic criteria. When the negative and atypical diagnoses were grouped together as "benign" and the suspicious and malignant diagnoses as "malignant," the detection rate of "malignancy" of the lesions was as follows: LMP, 37%; LGPUC, 25%; and HGPUC, 53%. The false positive rate was 6%, and the positive predictive value (PPV) was 94%. Detection rates of cells that were at least "atypical" were as follows: LMP, 74%; LGPUC, 79%; and HGPUC, 100%. While most of the LMP and LGPUC cases yielded cells that were at least "atypical," there was no significant difference in the distribution of cytologic diagnoses for LMP and LGPUC cases (P > 0.05). Urine cytology in the context of the 1998 WHO/ISUP classification appears to be useful as a screening tool but does not appear to discriminate LMP effectively from LGPUC.

Voided urine cytology of papillary renal cell carcinoma and renal calculus: report of a case with emphasis on the importance of cytologic screening in high-risk individuals.

BACKGROUND: Preoperative diagnosis of cases of renal calculus complicated with papillary renal cell carcinoma (RCC) by image analysis is usually difficult. CASE: A 50-year-old man who had a past history of renal calculus suffered from macrohematuria and abdominal pain for one month was admitted to our hospital. Ultrasonographic examination revealed a 4-cm tumor shadow in the right kidney; it was hypovascular in arteriography. Papillary cell clusters with abundant cytoplasm were found by the cytologic examination of voided urine. Their nuclei were oval and situated eccentrically in the cytoplasm. The nuclear/cytoplasmic ratio was increased. Fine, granular chromatin was distributed evenly, and the nuclear membrane was thin and nearly smooth. Several small nucleoli were evident. All these findings were indicative of a diagnosis of papillary RCC. Histology of nephrectomy specimens confirmed the diagnosis. CONCLUSION: Voided urine cytology can be useful for screening and follow-up of patients with papillary RCC.

Micropapillary variant of transitional cell carcinoma of the urinary bladder: a report of three cases with cytologic diagnosis in urine specimens.

BACKGROUND: Micropapillary transitional cell carcinoma is a recently described, aggressive variant of bladder cancer. Its cytologic features in urine have not been previously characterized. CASES: Three cases illustrate the urinary cytologic features of this high grade urothelial carcinoma and its concurrent biopsy findings. This tumor is similar to low. grade urothelial lesions of the bladder, tends to present as micropapillary clusters in urine and yet has high grade nuclear features within these clusters that help with the differential diagnosis of a flat, high grade urothelial carcinoma. CONCLUSION: The micropapillary type of transitional cell carcinoma is a distinct morphologic entity with an aggressive clinical course. Recognizing its presence in urinary cytology, albeit a rare occurrence, is important in distinguishing this lesion from the more indolent, low grade papillary lesions and high grade urothelial carcinomas, which continuously shed single malignant urothelial cells.