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Thomas J Sebo

Publications and source records attributed to Thomas J Sebo.

At least 19 recordsLinked to original sources

Prognostic value of p53 and MIB-1 in transitional cell carcinoma of the urinary bladder with regional lymph node involvement.

BACKGROUND: The effect of p53 protein expression and MIB-1 proliferative activity on survival and chemotherapeutic response in patients with lymph node (LN)-positive transitional cell carcinoma (TCC) of the urinary bladder remains unclear. The objective of this study was to assess the ability of these markers to predict disease-associated outcomes and response to chemotherapy in a cohort of patients with LN-positive TCC. METHODS: The authors examined the expression of p53 and MIB-1 in the LN metastases from 139 patients who underwent cystectomy for TCC at their institution. P53 and MIB-1 nuclear staining were quantified using an image-analysis system. Cox proportional hazards regression models were used to test associations of these markers with death from TCC, distant metastases, and local recurrence for all patients and in the subset of patients who were treated with adjuvant chemotherapy. RESULTS: The median p53 and MIB-1 indices were 45.2% and 30.3%, respectively. The median follow-up was 4.5 years (range, 0.1-10 years). There were no statistically significant associations noted between the p53 and MIB-1 indices and the outcomes studied. When the analysis was limited to patients who were treated with adjuvant chemotherapy (n = 37 patients), the p53 index was found to have no prognostic value; however, there was a significant association between MIB-1 and distant metastases (P = 0.049). When disease-specific survival rates were stratified according to p53 index and chemotherapy, patients exhibited a response to chemotherapy regardless of p53 index. CONCLUSIONS: p53 and MIB-1 were not found to be associated significantly with disease-related outcomes in patients with LN-positive TCC. Adjuvant chemotherapy appeared to be effective regardless of p53 status. MIB-1 may prove useful in predicting response to chemotherapy.

Biomarkers, Tumor↗

PPARgamma staining as a surrogate for PAX8/PPARgamma fusion oncogene expression in follicular neoplasms: clinicopathological correlation and histopathological diagnostic value.

The PAX8/PPARgamma (PPFP) fusion-oncogene is moderately specific for follicular thyroid carcinomas (FTC). It remains unknown whether this can be translated into improved diagnosis, classification, or outcome prediction. We studied a cohort of well-characterized follicular adenomas (FA), FTC, and Hurthle cell carcinomas (HCC) from patients with complete clinical follow-up, to determine whether PPARgamma immunohistochemistry (as a surrogate of PAX8/PPARgamma expression) helps to distinguish FA from FTC and to assess its diagnostic accuracy as an adjunct to frozen section. We also correlated PPARgamma staining with clinical outcomes to assess its role as a prognostic marker.PPARgamma staining was more common in FTC (31 of 54; 57%) than in HCC (one of 23; 4%) or FA (four of 31; 13%) (P < 0.000001). Adjunctive use of PPARgamma immunohistochemistry improved diagnostic sensitivity of intraoperative frozen section from 84% to 96% (P < 0.05) but reduced specificity from 100% to 90% (P < 0.05). PPARgamma staining was associated with favorable prognostic indicators (female gender, better tumor differentiation, and lesser risk of metastases).PPARgamma staining may be helpful in the differential diagnosis of FA, FTC, and HCC, particularly when diagnostic sensitivity of histomorphology is reduced (e.g. during intraoperative frozen section). PPARgamma staining also shows an association with favorable prognosis and may have a role in risk stratification.

Adenoma↗

Fine-needle aspiration cytology findings from a case of pancreatic heterotopia at the gastroesophageal junction.

Pancreatic heterotopia is a well-recognized entity occurring at a variety of sites in the gastrointestinal tract. However, only a handful of patients have been described with this abnormality at the gastroesophageal junction. Cytologic descriptions of pancreatic heterotopia in general are scant in the literature. We report the cytologic findings of ectopic pancreatic tissue at the gastroesophageal junction in a 41-year-old female, which was initially identified by endoscopic ultrasound and fine-needle aspiration. Cytologic examination of Papanicolaou-stained smears revealed clusters of benign-appearing ducts and small acini mixed with inflammatory cells. Hematoxylin and eosin staining of the Tru-Cut biopsy revealed benign pancreatic tissue. The patient underwent surgical resection due to symptoms related to inflammation of the heterotopic pancreatic tissue. The increasing use of endoscopic ultrasound and fine-needle aspiration for the diagnosis of gastrointestinal tumors makes the recognition of pseudoneoplastic lesions at unusual sites an important step in optimum patient management.

Adult↗

Histiocytes containing immunoglobulin crystals in the urine of a patient with IgA kappa plasmacytoma of the bladder.

Exfoliative cytology specimens from patients with plasma cell dyscrasias are rarely diagnostic, though there are reports of neoplastic plasma cells observed in pleural fluid and urine. Immunoglobulin concretions or crystals associated with neoplastic plasma cell populations have been well described. These crystals may be found within plasma cell nuclei or cytoplasm, extracellularly, or within cells of histiocytic lineage where they are presumably derived by phagocytosis. To the best of our knowledge, this is the first report of immunoglobulin crystals within histiocytes in the urine of a patient with plasmacytoma. A 61-year-old male underwent routine cystoscopy and urine collection to evaluate hematuria. The bladder biopsy demonstrated IgA kappa-producing plasmacytoma. Urine cytopsin preparations did not contain plasma cells, but there were histiocytic cells with degenerative nuclei and eccentrically located cytoplasmic spherical refractile hyaline crystals thought to be immunoglobulin crystals. This was supported by immunocytochemical staining.

Crystallization↗

A prospective comparison of digital image analysis and routine cytology for the identification of malignancy in biliary tract strictures.

BACKGROUND & AIMS: Digital image analysis (DIA) allows quantification of nuclear DNA content and may help distinguish benign and malignant strictures of the biliary tract. METHODS: One hundred ten consecutive patients undergoing endoscopic retrograde cholangiography for suspicious biliary tract strictures were enrolled in a prospective study comparing the accuracy of DIA and routine cytology (RC). Standard brush cytology sampling was performed twice by using 2 cytology brushes per patient. Both brushes were fixed in a single-specimen vial. Each specimen was formed into 1 pellet, and the sample was equally divided for evaluation by DIA and RC. DNA histograms were generated for ploidy analysis. The DIA criterion for malignancy was demonstration of aneuploidy. RESULTS: Two patients had inadequate samples obtained for DIA analysis, 7 benign patients were excluded because of inadequate follow-up of less than 75 days, and 1 patient was lost to follow-up to clarify malignant versus benign disease. Of the remaining 100 patients, 56 strictures were malignant and 44 were benign. The sensitivities of DIA and RC were 39.3% and 17.9%, respectively (P = 0.014). The specificities of DIA and RC were 77.3% and 97.7%, respectively (P = 0.003). The accuracy of DIA (56.0%) was equivalent to RC (53.0%). CONCLUSIONS: DIA is a valuable adjunct to RC for detecting malignant strictures of the biliary tract.

Adult↗

Hyalinizing trabecular adenoma of the thyroid gland: cytologic features in 29 cases.

Cytologic material (fine-needle aspiration biopsy smears, thin-layer preparations, cell block sections, and touch preparations) from 29 cases of hyalinizing trabecular adenoma was studied to 1) establish the cytologic profile of the neoplasm and 2) compare the profile with those of papillary and medullary carcinoma. Papanicolaou- and Diff-Quik-stained smears of the hyalinizing trabecular adenomas were uniformly bloody. The smears featured cells in cohesive aggregates radially oriented around hyaline material, less frequently, singly. Cytoplasm was abundant, and the nucleocytoplasmic ratio was low. Intranuclear cytoplasmic inclusions, nuclear grooves, and nuclear overlapping were very common and best seen with the Papanicolaou method. Diff-Quik-stained smears highlighted the hyaline material (metachromatic), perinucleolar clearing, and cytoplasmic bodies. The combination of a bloody background, radially oriented cohesive cells, cells with abundant cytoplasm, nuclei with very frequent cytoplasmic inclusions and grooves, and the presence of hyalin should suggest the presence of hyalinizing trabecular adenoma.

Adenoma↗

Observer variation in the diagnosis of follicular variant of papillary thyroid carcinoma.

The histopathologic diagnosis of follicular variant of papillary thyroid carcinoma (FVPCA) can be difficult. Recent reports have suggested that this neoplasm may be frequently overdiagnosed by pathologists. We examined the observer variation in the diagnosis of FVPCA in 87 tumors by 10 experienced thyroid pathologists. The criteria that the reviewers considered most helpful for making a diagnosis of FVPCA were also assessed. A concordant diagnosis of FVPCA was made by all 10 reviewers with a cumulative frequency of 39%. In this series, 24.1% of the patients had metastatic disease (n = 21). In the cases with metastatic disease, a diagnosis of FVPCA was made by all 10 reviewers with a cumulative frequency of 66.7%, and 7 of the reviewers made a diagnosis of FVPCA with a cumulative frequency of 100%. The most important criteria used to diagnose FVPCA included the presence of cytoplasmic invaginations into the nucleus (pseudo-inclusions), abundant nuclear grooves, and ground glass nuclei. These results suggest that although the diagnosis of FVPCA is variable even among experienced thyroid pathologists, most reviewers agreed on this diagnosis for patients with metastatic disease. The use of well-defined histopathologic features should improve the consistency in diagnosing FVPCA. Since most cases with metastatic disease had obvious invasion, caution should be used in making a diagnosis of FVPCA in the absence of the major histopathologic features or clear-cut invasive growth.

Carcinoma, Papillary, Follicular↗

A comparison of routine cytology and fluorescence in situ hybridization for the detection of malignant bile duct strictures.

BACKGROUND AND AIM: The aim of this study was to assess the relative sensitivities and specificities of fluorescence in situ hybridization (FISH) and routine cytology for the detection of malignancy in biliary tract strictures. METHODS: Bile duct brushing and aspirate specimens were collected from 131 patients being evaluated for possible malignant bile duct strictures. Both specimen types were assessed by FISH but only brushing specimens were assessed by cytology. The FISH assay used a mixture of fluorescently-labeled probes to the centromeres of chromosomes 3, 7, and 17 and chromosomal band 9p21 (Vysis UroVysion) to identify cells having chromosomal abnormalities. A case was considered positive for malignancy if five or more cells exhibited polysomy. RESULTS: Sixty-six of the 131 patients had surgical pathologic and/or clinical evidence of malignancy. Thirty-nine patients had cholangiocarcinoma, 19 had pancreatic carcinoma, and 8 had other types of malignancy. The sensitivity of cytology and FISH for the detection of malignancy in bile duct brushing specimens in these patients was 15% and 34% (p < 0.01), respectively. The sensitivity of FISH for the bile aspirate specimens was 23%, and the combined sensitivity of FISH for aspirate and brushing specimens was 35%. The specificity of FISH and cytology brushings were 91% and 98% (p= 0.06), respectively. CONCLUSIONS: FISH is significantly more sensitive than and nearly as specific as conventional cytology for the detection of malignant biliary strictures in biliary brushing specimens. FISH may improve the clinical management of patients who are being evaluated for malignancy in bile duct strictures.

Adolescent↗

Prospective, blinded assessment of factors influencing the accuracy of biliary cytology interpretation.

OBJECTIVES: There is little published data assessing factors that influence the accuracy of biliary cytology. The aim of this study was to (a) prospectively compare interobserver variability among two blinded pathologists interpreting biliary cytology specimens, (b) to describe the predictors of interpathologist agreement, and (c) to characterize the predictors of accurate cytology interpretation. METHODS: In total, 113 consecutive patients undergoing endoscopic retrograde cholangiopancreatography with brushing of suspicious biliary tract strictures were prospectively enrolled to assess routine cytology (RC) accuracy. The initial RC interpretation was performed by the pathologist on duty with the benefit of the patient's clinical information. Subsequent interpretation was performed by two independent pathologists blinded to the patients' clinical details. RESULTS: Of the 113 patients, 67 had malignant strictures and 46 had benign strictures. The sensitivity of RC varied from 9% to 24% (p= 0.02), while the specificity varied from 61% to 100% (p < 0.001). Accuracy varied from 43% to 51% (p= n.s.). The rate of equivocal readings was lowest for the initial interpretation (1.7%), p < 0.0001 versus pathologist 1, p= 0.002 versus pathologist 2. Overall correlation of the blinded pathologists' interpretations was moderate, k= 0.66. Neither cytology accuracy nor interpathologist agreement improved with increasing specimen cellularity. CONCLUSIONS: There is a high rate of interpathologist variation for the biliary cytology interpretation. The knowledge of the patient's clinical information appears to clarify cytology interpretation resulting in fewer equivocal results. We did not detect any reliable predictors of cytology accuracy.

Bile Duct Neoplasms↗

Hyalinizing trabecular adenoma of the thyroid gland identification through MIB-1 staining of fine-needle aspiration biopsy smears.

Smears of fine-needle aspiration (FNA) biopsy specimens of 24 histologically proven and MIB-1-positive hyalinizing trabecular adenomas stained with Papanicolaou or Diff-Quik were stripped from the original slides, transferred to charged slides, destained, and restained with MIB-1. Positive immunoreactivity with MIB-1 in a peripheral cytoplasmic pattern was present in 17 specimens, no immunoreactivity was seen in 4 specimens, and equivocal staining was seen in 3 specimens. Papanicolaou-stained smears of papillary thyroid carcinoma, medullary thyroid carcinoma, thyroid follicular neoplasm, and Hürthle cell adenoma (5 specimens each) were treated similarly. None of the control cases stained with MIB-1 had the peripheral cytoplasmic pattern. Hyalinizing trabecular adenoma can be distinguished reliably from other thyroid neoplasms by MIB-1 staining of destained cells from FNA biopsy specimens.

Adenoma↗

An analysis of the p63/alpha-methylacyl coenzyme A racemase immunohistochemical cocktail stain in prostate needle biopsy specimens and tissue microarrays.

We studied the usefulness of a p63/P504S immunostain "cocktail" in evaluation of prostate biopsy specimens containing atypical acini suspicious for adenocarcinoma (AASA), high-grade prostatic intraepithelial neoplasia (HPIN), and small foci of adenocarcinoma and tested the sensitivity and specificity of the immunostain with tissue microarrays (TMAs) constructed from prostatectomy and lymphadenectomy specimens. We selected 40 cases containing a focus of adenocarcinoma (14 cases), AASA (7 cases), AASA with HPIN (7 cases), HPIN (6 cases), and atypical favor benign (6 cases). After p63/P504S immunostaining, 13 cases (33%) were reclassified: AASA with HPIN to HPIN only in 5 cases (13%), atypical favor benign to benign in 4 cases (10%), AASA to adenocarcinoma in 2 cases (5%), and atypical favor benign to AASA and atypical favor benign to HPIN in 1 case (3%) each. The diagnosis of adenocarcinoma was supported by immunostain in 14 cases. In TMA studies, the p63/P504S immunostain for adenocarcinoma and HPIN had sensitivity values of 97.2% and 86.2%, respectively, and specificity values of 99.7% and 81.6%, respectively. P504S stained 64 (74%) of 87 cores of metastatic cancers, and no p63-positive cells were identified in the metastases. The p63/P504S immunohistochemical stain is a sensitive, specific marker for prostatic adenocarcinoma and HPIN and useful in the evaluation of AASA in biopsy specimens.

Adenocarcinoma↗

Microsatellite instability in hereditary and sporadic breast cancers.

Sporadic cancers and familial breast cancers are characterized by an increase in genetic instability. Little is known about whether mismatch repair defects accompany this genetic instability. We investigated invasive and/or in situ breast cancers from 30 women with deleterious BRCA1/2 mutations and unclassified variant BRCA1/2 alterations. Forty cases of sporadic breast cancers were also investigated, including 7 medullary carcinomas. Malignant and benign lesions were examined from all cases to better understand tumor progression. Automated immunohistochemistry, with antibodies directed against hMLH1 and hMSH2, was used to screen cases for possible mismatch repair defects. When loss of expression was noted, DNA ploidy was performed by cytomorphometry. DNA, after laser microdissection, was extracted from a majority of familial cases and their corresponding controls, and microsatellite instability analysis was performed. None of the familial or sporadic cases had loss of hMSH2 expression. All but one lesion, a DCIS arising in a deleterious BRCA2 mutation carrier, had loss of hMLH1 expression and a tetraploid profile by image cytomorphometry. There was no MSI in any explored lesions (n = 34), as determined by molecular analysis, including the DCIS with loss of hMLH1 expression. We conclude that DNA mismatch repair defects involving hMLH1 and hMSH2 underexpression are extremely rare events in sporadic and familial breast cancer. Mismatch repair gene mutations may be secondary random events in breast cancer progression.

Adaptor Proteins, Signal Transducing↗

p300 in prostate cancer proliferation and progression.

Although prostate cancer (PCa) is the most frequently diagnosed cancer in males, little is known about the mechanisms involved in its progression. Recent in vitro studies suggest that coactivators of the androgen receptor play an important role in PCa progression. We have shown previously that p300 is involved in androgen receptor transactivation. In the present work, we studied 95 patients with biopsy-proven PCa who underwent prostatectomy as treatment of their tumors between 1995 and 1998. We found that p300 correlated with in vivo proliferation (P = 0.009) as determined by MIB-I expression. Moreover, high levels of p300 in biopsies predicted larger tumor volumes (P < 0.001), extraprostatic extension (P = 0.003), and seminal vesicle involvement (P = 0.002) at prostatectomy, as well as PCa progression after surgery (P = 0.01). Furthermore, we found that the disruption of p300 transcripts through small interfering RNA inhibited PCa cell proliferation both at the basal level and on interleukin 6 stimulation. We conclude that p300 plays an important role in PCa cell proliferation, as well as PCa progression.

Acetyltransferases↗

Pathologic characteristics of breast parenchyma in patients with hereditary breast carcinoma, including BRCA1 and BRCA2 mutation carriers.

BACKGROUND: BRCA1 and BRCA2 alterations are associated with an increased risk of developing breast carcinoma. The authors hypothesized that the progression of breast neoplasia may differ between patients with hereditary disease and patients with nonhereditary disease and that this difference in progression may be visualized by studying the prevalence of precursor lesions and neoplastic lesions. METHODS: The authors developed two case cohorts of high-risk patients with a strong family history of breast carcinoma who underwent prophylactic mastectomy. The first cohort was comprised of women who underwent therapeutic mastectomy and contralateral prophylactic mastectomy, and the second cohort was comprised of women who underwent bilateral prophylactic mastectomy. Patients without a family history of breast carcinoma who underwent unilateral or bilateral prophylactic mastectomy were selected as a control group. DNA from peripheral blood leukocytes was screened for BRCA1 and BRCA2 mutations. The available pathologic materials were reviewed independently by two pathologists, and all neoplastic and precursor lesions were identified and classified. Proliferation activity was assessed using MIB-1 immunohistochemistry on all available lesions from the unilateral mastectomy cohort. RESULTS: The 28 women from the unilateral cohort with deleterious BRCA1/2 mutations had a lower prevalence of proliferative fibrocystic changes (PFC) (7%) compared with their matched control group (25%) (P = 0.075) and with patients who had a family history but no BRCA1/2 mutation (22-33%). None of the 11 deleterious mutation carriers from the bilateral cohort (0%) had PFC compared with 36% of women in the matched control group (P = 0.03). There was no major difference in the prevalence of other precursor lesions (including in situ carcinoma) in either cohort. Invasive carcinomas from the deleterious mutation carriers in the unilateral cohort were of higher grade compared with the control group (P = 0.003) and patients without a mutation (P < 0.0001) but were of similar grade compared with carriers of unclassified variant BRCA1/2 alterations (P = 0.20). Neoplastic lesions from the deleterious mutation carriers in the unilateral cohort had higher MIB-1 proliferation indices compared with other patients with and without a family history of breast carcinoma. CONCLUSIONS: The current data suggest that the progression rate of breast neoplasia is accelerated in women who carry BRCA1/2 deleterious mutations compared with other patients who have breast carcinoma with or without a family history. This increased progression rate should be taken into account when considering the surveillance of asymptomatic women.

Adenocarcinoma↗

Molecular and histopathologic predictors of distant failure in endometrial cancer.

A case-cohort study was designed to correlate various histopathologic and molecular variables with distant failure in endometrial cancer by analyzing phenotypic and molecular indices in hysterectomy specimens. From an overall population of 283 patients with endometrial cancer, we selected a cohort including all 49 patients who experienced any recurrence and 76 randomly chosen patients without recurrence. Expression of nuclear proliferating cell nuclear antigen (PCNA), MIB-1 (a marker of cell proliferation), and p53 was determined with digital image analysis, and cell membrane HER-2/neu and bcl-2 were quantitated visually. Ploidy and DNA indices were determined with flow cytometry. Overall, 6 immunohistochemical and 11 flow cytometric cases were eliminated because of technical inadequacies. Distant failures were defined as primary recurrences that developed outside the pelvis or vagina. Median follow-up was 91 months. Distant failures occurred in 13% of the patients. Cervical stromal invasion, positive adnexae, myometrial invasion >50%, positive lymph nodes, positive peritoneal cytology, lymphovascular invasion, grade 3 histology, nonendometrioid subtype, p53 >33%, strong HER-2/neu membranous staining, aneuploidy, S-phase fraction > or =9%, proliferative index > or =14%, and DNA index > or =1.5 significantly (P<0.05) predicted distant failures. However, a logistic regression model identified only p53 (OR=43.73; P<0.005), lymphovascular invasion (OR=11.59; P<0.001), and cervical stromal invasion (OR=11.29; P=0.001) as cogent predictors of distant failures. Only 3% of patients without any of these three predictors developed distant failures compared with 36% of those with at least one of the three (P<0.01). Thus, locoregional therapy may be insufficient when at least one of these predictors is present.

Adult↗

Prospective analysis of computerized tomography and needle biopsy with permanent sectioning to determine the nature of solid renal masses in adults.

PURPOSE: We prospectively determined the accuracy of computerized tomography (CT) and needle biopsy of solid renal masses. MATERIALS AND METHODS: A total of 100 patients with a solid renal mass who were scheduled for operation were prospectively evaluated. CT was performed before radical or partial nephrectomy. Biopsy of the surgical specimens was done twice through the tumor using an 18 gauge biopsy gun. Specimens were sent for permanent section and review by 2 pathologists blinded to each other and to the whole tissue specimens. Images were reviewed by 2 radiologists blinded to each other and to the results of pathological analysis. Results of CT and permanent biopsy were compared with the results of whole tissue specimen analysis. RESULTS: Specimens were obtained from 59 radical and 41 partial nephrectomies. Malignant neoplasms were present in 85 patients (85%). Overall accuracy was 77% and 72%, the nondiagnostic rate was 20% and 21%, sensitivity was 81% and 83%, and specificity was 60% and 33%. For the 2 radiologists overall accuracy was 60% and 66%, the nondiagnostic rate was 31% and 23%, sensitivity was 70% and 77%, and specificity was 20% and 20%, respectively. CONCLUSIONS: Overall permanent biopsy results were accurate in more than 72% of cases and CT was accurate in more than 60%. However, because the nondiagnostic rate for CT and needle biopsy was 20% and 31%, respectively, and specificity was low, we do not recommend routine preoperative CT and subsequent needle biopsy to guide treatment decision making. Rather, cases must be decided individually.

Adult↗

Nephron-sparing surgery for renal cell carcinoma: clinicopathologic features predictive of patient outcome.

OBJECTIVES: To determine the clinicopathologic features associated with outcome in patients with sporadic renal cell carcinoma (RCC) treated with nephron-sparing surgery. METHODS: We studied 344 patients treated with nephron-sparing surgery between 1970 and 2000. The pathologic features of the tumors were reviewed by two urologic pathologists who recorded the histologic subtype, 2003 TNM stage, tumor size, and grade. Cancer-specific survival (CSS) was estimated using the Kaplan-Meier method, and log-rank tests were used to compare the outcome by histologic subtype. Univariate Cox proportional hazards models were fit to assess the associations between the clinicopathologic features and death from RCC, distant metastases, and local recurrence. RESULTS: The CSS rate at 5 and 10 years for patients with clear cell RCC was 94.4% and 91.5%, respectively. In contrast, the CSS rate at 5 and 10 years for patients with papillary or chromophobe RCC was 99.0%, because only 1 patient died of papillary RCC and no patient died of chromophobe RCC (P = 0.029). Among the patients with localized clear cell RCC, tumor stage and grade were significantly associated with death from RCC and metastases. Grade was significantly associated with local recurrence for clear cell RCC, but not for papillary RCC. CONCLUSIONS: In our series of patients with RCC treated with nephron-sparing surgery, patients with clear cell RCC had a significantly worse CSS than did patients with papillary and chromophobe RCC. Tumor stage and grade were associated with outcome among patients with localized clear cell RCC. These findings are similar to the results for patients with localized clear cell RCC treated with radical nephrectomy.

Adult↗

Dedifferentiation in low-grade mucoepidermoid carcinoma of the parotid gland.

Mucoepidermoid carcinoma (MEC), a common malignant salivary gland neoplasm, is generally divided into low-, intermediate-, and high-grade types according to the histologic features. To our knowledge, the present report describes the first case of dedifferentiation occurring in a low-grade MEC. A 55-year-old man presented with a biphasic neoplasm of the right parotid gland composed of low-grade MEC and dedifferentiated high-grade anaplastic undifferentiated carcinoma. Immunohistochemically, carcinoembryonic antigen expression was restricted to the low-grade MEC portion. The Ki-67-labeling index was higher in the dedifferentiated component than in the low-grade component. On image cytometric analysis, the low-grade MEC was diploid, whereas the dedifferentiated carcinoma was aneuploid. Although the patient was alive 10 years after the initial diagnosis, the tumor has recurred twice, at 3 months and 7 months after the initial resection. It is important to recognize that dedifferentiation can occur in a low-grade MEC, similar to other low-grade salivary gland carcinomas.

Aneuploidy↗