Use of cytological samples of metastatic melanoma for ancillary studies.

OBJECTIVE: Fine needle aspiration (FNA) is widely used in the diagnosis of metastatic melanoma, both at initial presentation and in the setting of recurrent disease. The purpose of this study was to evaluate the performance of confirmatory immunohistochemistry (IHC) and molecular analysis of the BRAF mutation in cytological preparations of metastatic melanoma. METHODS: A 2-year retrospective review of pathology reports was performed on cytological samples of metastatic melanoma at the University Health Network (Toronto, Canada) and the Santa Casa Medical School (Sao Paulo, Brazil). IHC was performed on cell block sections prepared from formalin-fixed, fresh samples or residuum of CytoLyt/PreservCyt post-fixed in formalin. BRAF V600E/K mutations were assessed by amplification refractory mutation system (ARMS) analysis. RESULTS: A total of 104 samples (94 FNAs and 10 fluids) from 83 patients (20 women, 63 men) were included. IHC was attempted in 43 cases (41.3%) and successful in 41 (95.3%). The panel number of antibodies ranged from 1 to 15 (median 3). The most frequently used melanoma markers included HMB-45, melanoma cocktail and S100 protein, used in 25 (58.1%), 23 (53.5%) and 18 samples (41.9%). Thirty cases (69.8%) used three or fewer markers. The BRAF V600E/K mutation was tested in eight samples, being successful in seven (87.5%) and positive in three (37.5%). CONCLUSIONS: Cytological samples are a reliable and sufficient source for IHC and subsequent molecular analysis, allowing a reduced diagnostic time and rapid, appropriate treatment options in patients with advanced melanoma.

Epstein-Barr virus encoded RNA detected by in situ hybridization using cytological preparations.

OBJECTIVE: Detection of Epstein-Barr virus (EBV) status might help in the diagnosis of EBV-related neoplasms. The rate of successful assays for the detection of EBV-infected cells in cytological preparations has not been fully explored. Our aims were to examine the rate of successful in situ hybridization (ISH) assays for EBV-encoded RNA (EBER) in cytological specimens and to explore reasons for failure. METHODS: An electronic search selected cases with ISH-EBER assays performed on cytological preparations during a 10-year period. Data regarding patient age, gender and immune status, sample type and site, type of preparation, ISH-EBER results, immunophenotyping and immunohistochemistry results, final diagnosis and correspondent histopathological samples were retrieved. RESULTS: Sixty specimens from 58 patients with diagnoses of lymphoproliferative disorder (n = 35), carcinoma (n = 24) and sarcoma (n = 1) were identified. ISH-EBER assays were performed on 50 cell block sections and on 10 cytospin preparations, with 22 positive and 32 negative results. Six tests (four cytospins and two cell block sections) failed owing to loss of material during the assay and background staining, with an overall failure rate of 10% and 4% if cytospins were excluded. Assays were performed on 13 cytology and surgical specimens from the same site, with only one discrepant result. CONCLUSIONS: Cell block sections had more successful ISH-EBER assays when compared with cytospins. Reasons for failure were loss of material on the slide and background staining. A high concordance rate with surgical specimens emphasizes the usefulness of cytological samples for determining EBV status in patients with exhausted or no histological material available.

Cytomorphological and clinicopathological spectrum of pulmonary marginal zone lymphoma: the utility of immunophenotyping, PCR and FISH studies.

OBJECTIVE: To review cytomorphological criteria and clinicopathological findings in combination with ancillary tests for the specific diagnosis of pulmonary marginal zone lymphoma (MZL) in fine needle aspiration (FNA) specimens. METHODS: Cases of pulmonary MZL diagnosed using cytological specimens from 2005 to 2012 were retrieved and reviewed by three cytopathologists. Results of immunophenotypic analysis, interphase fluorescence in situ hybridization (FISH) and molecular assays were collated, together with clinical information and imaging data. Concurrent surgical biopsies were also retrieved. RESULTS: Fifteen lung FNA specimens were identified. The smears consisted predominantly of small centrocyte-like cells. Marked plasma cell differentiation was evident in 11 cases. All cases with slides available showed tissue fragments with lymphoid tangles (TFLTs). Multinucleated giant cells were present in nine cases, two of which showed granulomas. Immunophenotyping confirmed B-cell clonality in all cases. B-cell clonality was detected by polymerase chain reaction (PCR) in two samples. FISH identified MALT1 translocation in four of 10 cases tested and trisomy 3 in three of four cases. Concurrent surgical biopsies were diagnosed independently as MZL in seven cases. CONCLUSIONS: Cytology smears from lung FNA samples consisting of small lymphoid cells with a relative abundance of plasma cells or plasmacytoid cells and large TFLTs should prompt immunophenotyping and other ancillary studies, even if multinucleated giant cells and poorly formed granulomas are also identified. Specific diagnosis of pulmonary MZL in FNA samples can be rendered on the basis of morphological features coupled with the demonstration of B-cell clonality by immunophenotyping or PCR and cytogenetic abnormalities by FISH.

CFTR biomarkers: time for promotion to surrogate end-point.

In patients with cystic fibrosis, cystic fibrosis transmembrane conductance regulator (CFTR) biomarkers, such as sweat chloride concentration and/or nasal potential difference, are used as end-points of efficacy in phase-III clinical trials with the disease modifying drugs ivacaftor (VX-770), VX809 and ataluren. The aim of this project was to review the literature on reliability, validity and responsiveness of nasal potential difference, sweat chloride and intestinal current measurement in patients with cystic fibrosis. Data on clinimetric properties were collected for each biomarker and reviewed by an international team of experts. Data on reliability, validity and responsiveness were tabulated. In addition, narrative answers to four key questions were discussed and agreed by the team of experts. The data collected demonstrated the reliability, validity and responsiveness of nasal potential difference. Fewer data were found on reliability of sweat chloride concentration; however, validity and responsiveness were demonstrated. Validity was demonstrated for intestinal current measurement, but further information is required on reliability and responsiveness. For all three end-points, normal values were collected and further research requirements were proposed. This body of work adds useful information to support the promotion of CFTR biomarkers to surrogate end-points and to guide further research in the area.

Worrisome histologic alterations following fine-needle aspiration of the parathyroid.

Fine-needle aspiration (FNA) is a procedure that is increasingly being performed. Artefacts occurring after FNA are reported to complicate the histological analysis of the tissue, mainly in the thyroid; WHAFFT (worrisome histologic alterations following FNA of thyroid) is well documented in the literature. The case of a male patient with hypercalcaemia who was subsequently found to have a nodule in the thyroid gland is reported here. He underwent FNA, followed by a total thyroidectomy and parathyroidectomy. The abnormality in the parathyroid gland showed worrisome histological changes that were suspicious of a malignant lesion, resembling the changes seen in the thyroid gland after FNA. Parathyroid cells were identified by a review of the previous FNA. The concept of WHAFFT, which can mimic the features of malignancy in the parathyroid gland, is therefore introduced.

[Doing voluntary extra work? Organizational citizenship behavior in the hospital--a comparison between physicians and nurses]. / Freiwillig mehr tun? Organizational Citizenship Behavior im Krankenhaus -- ein Vergleich zwischen Arzten und Pflegekräften.

AIM OF THE STUDY: The study compares physicians and the nursing staff of a hospital in terms of their extra-role behavior. Matters of interest include the extent of Organizational Citizenship Behavior (OCB) shown on the one hand and on the other hand which conditions stimulate the OCB of both physicians and nurses, respectively. METHOD: The comparison was conducted by applying a questionnaire on n = 70 physicians and n = 112 nurses in a nursing department of a municipal hospital. RESULTS: The results can be summarized as follows: (1) The extra-role behavior in terms of sportsmanship, individual initiative, and conscientiousness show equally high values with respect to physicians as well as nurses. In contrast, nurses rate their own helping behavior towards colleagues higher than the physicians do. Therefore, the extent of OCB does not seem to be job-specific in the narrower sense. (2) Differences between physicians and nurses exist indeed with respect to the conditions for the occurrence of OCB: Although the extent of OCB shown by physicians and nurses is independent from age, department tenure, and organizational tenure, job experience does play a role for the degree of conscientiousness (physicians) and individual initiative (nurses). Furthermore, gender affects the sub dimension sportsmanship (nurses). (3) While job characteristics (job control and stress) play a certain role for the degree of nurses' OCB, the physicians' extra-role behavior is independent from job control and strain. Vice versa, the analyzed person-related characteristics job insecurity and strain play a role for the extra-role behavior of physicians, while the behavior of nurses remains unaffected hereof. In other words: Nurses show the same OCB at high and low levels of strain and job insecurity, while physicians lower their OCB when strain and job insecurity rise. (4) For both physicians and nurses, job satisfaction is the most important predictor for extra-role behavior. CONCLUSION: When trying to enhance the extent of OCB within a hospital, it is -- according to our results -- primarily essential to increase the job satisfaction of physicians as well as nurses. Within the nursing department, it is additionally recommended to enhance the employees' scope of action, if possible. However, for the enhancement of OCB it must be kept in mind -- according to our results -- that with rising OCB the stress (e. g. time pressure and interruptions) rise at the same time. The latter might result in higher strain for employees. In the group of physicians, on the other hand, a person-related approach seems promising: it is essential to reduce the physicians' subjectively felt strains as well as the job insecurity.

Cutaneous manifestations of thyroid cancer: a report of four cases and review of the literature.

Cutaneous metastases from thyroid carcinoma are rare. This report describes four cases of thyroid carcinoma metastatic to the skin. Two cases were medullary carcinoma and two were papillary thyroid carcinoma. In two cases, skin metastases were the presenting feature of the underlying thyroid carcinoma. Examination of the skin lesions by conventional light microscopy suggested the possibility of metastatic carcinoma and immunohistochemical tests confirmed the diagnosis. Subsequent investigations identified primary thyroid lesions. In two cases, the skin metastasis was the first evidence of the recurrence of known thyroid carcinoma. These cases identify a novel presentation of thyroid carcinoma.

Effect of P-glycoprotein on flavopiridol sensitivity.

Flavopiridol is the first potent inhibitor of cyclin-dependent kinases (CDKs) to enter clinical trials. Little is known about mechanisms of resistance to this agent. In order to determine whether P-glycoprotein (Pgp) might play a role in flavopiridol resistance, we examined flavopiridol sensitivity in a pair of Chinese hamster ovary cell lines differing with respect to level of Pgp expression. The IC(50)s of flavopiridol in parental AuxB1 (lower Pgp) and colchicine-selected CH(R)C5 (higher Pgp) cells were 90.2 +/- 6.6 nM and 117 +/- 2.3 nM, respectively (P< 0.01), suggesting that Pgp might have a modest effect on flavopiridol action. Consistent with this hypothesis, pretreatment with either quinidine or verapamil (inhibitors of Pgp-mediated transport) sensitized CH(R)C5 cells to the antiproliferative effects of flavopiridol. Because of concern that colony forming assays might not accurately reflect cytotoxicity, we also examined flavopiridol-treated cells by trypan blue staining and flow cytometry. These assays confirmed that flavopiridol was less toxic to cells expressing higher levels of Pgp. Further experiments revealed that flavopiridol inhibited the binding of [3H]-azidopine to Pgp in isolated membrane vesicles, but only at high concentrations. Collectively, these results identify flavopiridol as a weak substrate for Pgp.

The HER tyrosine kinase inhibitor CI1033 enhances cytotoxicity of 7-ethyl-10-hydroxycamptothecin and topotecan by inhibiting breast cancer resistance protein-mediated drug efflux.

Because the activities of HER family members are elevated and/or aberrant in a variety of human neoplasms, these cell surface receptors are receiving increasing attention as potential therapeutic targets. In the present study, we examined the effect of combining the HER family tyrosine kinase inhibitor CI1033 (PD 183805) with the topoisomerase (topo) I poison 7-ethyl-10-hydroxycamptothecin (SN-38), the active metabolite of irinotecan, in a number of different cell lines. Colony-forming assays revealed that the antiproliferative effects of simultaneous treatment with CI1033 and SN-38 were synergistic in T98G glioblastoma cells and HCT8 colorectal carcinoma cells, whereas sequential treatments were additive at best. In additional studies examining the mechanistic basis for these findings in T98G cells, immunoblotting revealed that the inhibitory effects of CI1033 on epidermal growth factor receptor autophosphorylation were unaffected by SN-38. Likewise, CI1033 had no effect on topo I polypeptide levels, localization, or activity. Nonetheless, CI1033 markedly enhanced the number of covalent topo I-DNA complexes stabilized by SN-38 or the related agent topotecan (TPT). Analysis of intracellular SN-38 levels by high-performance liquid chromatography and intracellular TPT levels by flow microfluorometry revealed that CI1033 increased the steady-state accumulation of SN-38 and TPT by 9.4 +/- 1.9- and 1.8 +/- 0.2-fold, respectively. Further evaluation revealed that the initial rate of TPT uptake was unaffected by CI1033, whereas the rate of efflux was markedly diminished. Additional studies demonstrated that T98G and HCT8 cells express the breast cancer resistance protein (BCRP), a recently cloned ATP binding cassette transporter. Moreover, CI1033 enhanced the uptake and cytotoxicity of SN-38 and TPT in cells transfected with BCRP but not empty vector. Conversely, CI1033 accumulation was diminished in cells expressing BCRP, suggesting that CI1033 is a substrate for this efflux pump. These results indicate that CI1033 can modulate the accumulation and subsequent cytotoxicity of two widely used topo I poisons in cells that have no history of previous exposure to these agents.

Hyalinizing trabecular tumor of the thyroid: a variant of papillary carcinoma proved by molecular genetics.

Hyalinizing trabecular tumors of the thyroid are interesting but uncommon neoplasms. They have been classified as benign hyalinizing trabecular adenomas or malignant hyalinizing trabecular carcinomas. They share both epidemiologic and morphologic features with papillary carcinoma, and there has been much speculation about the relationship between these two entities. Because RET/PTC gene rearrangements are specific to papillary thyroid carcinoma, the authors examined the presence of RET/PTC-1, -2, and -3 in eight hyalinizing trabecular tumors using reverse transcription-polymerase chain reaction with Southern hybridization and immunohistochemistry. They detected the presence of a RET/PTC gene rearrangement in six of the eight hyalinizing trabecular tumors. This confirms the long-standing suspicion that hyalinizing trabecular tumors do indeed represent a morphologic variant of papillary carcinoma.

Effect of 6-aminonicotinamide and other protein synthesis inhibitors on formation of platinum-DNA adducts and cisplatin sensitivity.

The present study was undertaken to examine the mechanistic basis for the recent observation that the pyridine nucleotide derivative 6-aminonicotinamide (6AN, NSC 21206) enhances the accumulation and resulting cytotoxicity of cisplatin in a variety of tumor cell lines. When A549 lung cancer cells or K562 leukemia cells were treated with 62.5 microM 6AN for 21 h and then pulse-labeled with [(35)S]methionine for 1 h, increased labeling of five polypeptides, one of which corresponded to a M(r) approximately 78,000 glucose-regulated protein (GRP78), was observed. Two subsequent observations, however, suggested that up-regulation of these polypeptides was unlikely to explain the interaction between 6AN and cisplatin: 1) the concentration of 6AN required to induce GRP78 was 4-fold higher than the dose required to sensitize cells to cisplatin; and 2) simultaneous treatment of cells with 6AN and cycloheximide prevented the increase in GRP78 but not the sensitizing effect of 6AN. On the contrary, treatment with the protein synthesis inhibitors cycloheximide, anisomycin, or puromycin as well as prolonged exposure to the RNA synthesis inhibitor actinomycin D mimicked the biochemical modulating effects of 6AN on cisplatin action. Conversely, 6AN inhibited protein synthesis, whereas 18 6AN analogs that failed to enhance Pt-DNA adducts and cisplatin cytotoxicity failed to inhibit protein synthesis. These observations are consistent with a model in which 6AN and other inhibitors of protein synthesis act as modulating agents by increasing cisplatin accumulation, thereby enhancing the formation of Pt-DNA adducts and subsequent cisplatin-induced cell death.

Characterization of an ovarian carcinoma cell line resistant to cisplatin and flavopiridol.

Flavopiridol, the first inhibitor of cyclin-dependent kinases to enter clinical trials, has shown promising antineoplastic activity and is currently undergoing Phase II testing. Little is known about mechanisms of resistance to this agent. In the present study, we have characterized an ovarian carcinoma cell line [OV202 high passage (hp)] that spontaneously developed drug resistance upon prolonged passage in tissue culture. Standard cytogenetic analysis and spectral karyotyping revealed that OV202 hp and the parental low passage line OV202 shared several marker chromosomes, confirming the relatedness of these cell lines. Immunoblotting demonstrated that OV202 and OV202 hp contained similar levels of a variety of polypeptides involved in cell cycle regulation, including cyclin-dependent kinases 2 and 4; cyclins A, D1, and E; and proliferating cell nuclear antigen. Despite these similarities, OV202 hp was resistant to flavopiridol and cisplatin, with increases of 5- and 3-fold, respectively, in the mean drug concentrations required to inhibit colony formation by 90%. In contrast, OV202 hp and OV202 displayed indistinguishable sensitivities to oxaliplatin, paclitaxel, topotecan, 1,3-bis(2-chloroethyl)-1-nitrosourea, etoposide, doxorubicin, vincristine, and 5-fluorouracil, suggesting that the spontaneously acquired resistance was not attributable to altered P-glycoprotein levels or a general failure to engage the cell death machinery. After incubation with cisplatin, whole cell platinum and platinum-DNA adducts measured using mass spectrometry were lower in OV202 hp cells than OV202 cells. Similarly, after flavopiridol exposure, whole cell flavopiridol concentrations measured by a newly developed high performance liquid chromatography assay were lower in OV202 hp cells. These data are consistent with the hypothesis that acquisition of spontaneous resistance to flavopiridol and cisplatin in OV202 hp cells is due, at least in part, to reduced accumulation of the respective drugs. These observations not only provide the first characterization of a flavopiridol-resistant cell line but also raise the possibility that alterations in drug accumulation might be important in determining sensitivity to this agent.

Murine pharmacokinetics of 6-aminonicotinamide (NSC 21206), a novel biochemical modulating agent.

The pyridine nucleotide 6-aminonicotinamide (6AN) was shown recently to sensitize a number of human tumor cell lines to cisplatin in vitro. The present studies were undertaken to compare the drug concentrations and length of exposure required for this sensitization in vitro with the drug exposure that could be achieved in mice in vivo. Human K562 leukemia cells and A549 lung cancer cells were incubated with 6AN for various lengths of time, exposed to cisplatin for 1-2 hr, and assayed for Pt-DNA adducts as well as the ability to form colonies. K562 cells displayed progressive increases in Pt-DNA adducts and cisplatin sensitivity during the first 10 hr of 6AN exposure. An 18-hr 6AN exposure was likewise more effective than a 6-hr 6AN exposure in sensitizing A549 cells to cisplatin. HPLC analysis of 6AN and its metabolite, 6-amino-NAD+, permitted assessment of exposures achieved in vivo after i.v. administration of 10 mg/kg of 6AN to CD2F1 mice. 6AN reached peak serum concentrations of 80-90 microM and was cleared rapidly, with T1/2alpha and T1/2beta values of 7.4 and 31.3 min, respectively. Bioavailability was 80-100% with identical plasma pharmacokinetics after i.p. administration. At least 25% of the 6AN was excreted unchanged in the urine. The metabolite 6-amino-NAD+ was detected in perchloric acid extracts of brain, liver, kidney, and spleen, but not in serum. Efforts to prolong systemic 6AN exposure by administering multiple i.p. doses or using osmotic pumps resulted in lethal toxicity. These results demonstrated that 6AN exposures required to sensitize tumor cells to cisplatin in vitro are difficult to achieve in vivo.

Ultrasound-guided fine-needle aspiration (FNA) of nonpalpable breast lesions: a review of 1885 FNA cases using the National Cancer Institute-supported recommendations on the uniform approach to breast FNA.

BACKGROUND: A probabilistic approach to the classification of fine-needle aspirates (FNAs) of the breast recently was recommended and received endorsement from the National Cancer Institute (NCI). In this system, FNAs are classified as benign, indeterminate/atypical, suspicious/probably malignant, and malignant, but to the authors' knowledge the use of these diagnostic categories has not been evaluated on a large scale. Furthermore, this classification scheme has not been applied to FNAs of nonpalpable lesions of the breast obtained under imaging guidance. Thus, the current study focused on whether the diagnostic categories could be applied usefully to ultrasound-guided FNAs (US-FNAs) of nonpalpable breast lesions. METHODS: Between 1988-1996, 1885 US-FNAs were performed on 1639 patients. The original FNA diagnoses were reclassified into the NCI-supported recommendations for diagnostic categories of breast FNAs. The cytologic findings were correlated with the tissue specimens, which were available in 851 cases, or with clinical follow-up of a minimum of 2 years in 127 of the 274 patients with benign solid lesions. RESULTS: The 1885 cases were categorized as follows: 1057 (56.1%) as benign, 86 (4.6%) as atypical, 79 (4.2%) as probably malignant, 502 (26.6%) as malignant, and 161 (8.5%) as unsatisfactory (defined as < 6 epithelial cell groups on all slides). The benign US-FNAs included 480 (45.4%) cysts and 577 (54.6%) solid lesions. Combined clinical and surgical follow-up showed that the frequency of malignancy was 3.7% in US-FNAs classified as benign, 52.9% in those designated as atypical, 75.8% in those designated as suspicious, and 98.9% in those classified as malignant. Based on combined histologic and clinical follow-up, a sensitivity of 97.1% and specificity of 99.1% were found for US-FNAs when definitive benign and malignant diagnoses were considered. A false-negative rate of 3.7% was attributed to sampling error. A false-positive rate of 0.68% was secondary to interpretative error of proliferative lesions. CONCLUSIONS: Application of the NCI-supported diagnostic categories to US-FNA of nonpalpable breast lesions is useful in stratifying aspirates based on the likelihood of underlying malignancy. The subcategories of US-FNAs diagnosed as atypical have similar probabilities of malignancy; this justifies their being grouped as a single category wherein tissue biopsy would be required to exclude carcinoma. Benign and inadequate FNA diagnoses must be correlated with the clinical and imaging findings and in noncorrelative cases the patient should undergo biopsy. US-FNA is a sensitive and specific means with which to diagnose nonpalpable breast lesions.

A one-step method for protein estimation in biological samples: nitration of tyrosine in nitric acid.

A number of methods are commonly employed for the determination of protein in biological samples. Unfortunately, several compounds that are constituents of biological buffers interfere with these methods, limiting their application. Previous studies have demonstrated that tyrosine rapidly undergoes nitration in nitric acid to yield 3-nitrotyrosine, which has a lambdamax of 358 nm. Utilizing this reaction, we have developed a one-step method for the assessment of protein content in biological samples. Common interfering substances, including SDS, urea, glycerol, ammonium sulfate, and beta-mercaptoethanol, do not interfere with this method. Because of its simplicity, this reaction might be useful for estimating protein content in a variety of biological samples.

Specimen adequacy and false-negative diagnosis rate in fine-needle aspirates of palpable breast masses.

BACKGROUND: As fine-needle aspiration (FNA) has become a critical component of the investigation of palpable breast masses, false-negative diagnoses have become a major concern, prompting reevaluation of the definition of specimen adequacy. Although cytopathologists agree that a number of parameters relate to the adequacy of an FNA specimen, there is no unanimity on the role of epithelial cell quantitation in the determination of an adequate FNA. To better understand the significance of epithelial cellularity, false-negative FNA samples from palpable breast lesions were reviewed. METHODS: False-negative FNA smears of palpable breast masses that had been performed and assessed immediately by cytopathologists were retrieved from the files of The University of Texas M. D. Anderson Cancer Center, and the number of epithelial cell clusters (ECCs) was determined. Aspirates were classified as adequate if a total of six or more ECCs (each comprised of at least five to ten well preserved cells) were present on all slides, or as inadequate if fewer than six ECCs were present. RESULTS: From 4455 aspirates of palpable breast masses, 51 false-negative aspirates were identified, 41 of which were available for review. No interpretative errors were identified. Twenty-one FNAs (51.2%) were classified as adequate and 20 FNAs (48.8%) as inadequate. The adequate false-negative aspirates contained between 8 to 100 ECCs. A comparison of adequate and inadequate false-negative specimens showed no significant differences in the mean age of patients (56.4 years vs. 57.8 years), the mean number of FNA passes (3.7 passes vs. 3.0 passes), the mean palpation size of the lesions (2.8 cm vs. 2.9 cm), or the mean pathologic size of the lesions (2.1 cm vs. 2.2 cm). Cases of invasive lobular carcinoma were more common in the false-negative smears with fewer than six ECCs. CONCLUSIONS: Including the number of ECCs as a parameter of adequacy could reduce the rate of false-negative FNA diagnoses of palpable breast masses by approximately 50%. However, the presence or even abundance of ECCs does not eliminate the potential for a false-negative cytologic diagnosis. Cytologic diagnoses must be correlated with clinical and imaging findings (the triple test) to reduce the rate of false-negative cases, but benign triple test results do not entirely exclude the possibility of carcinoma, and such cases require periodic follow-up.

Giant pseudocyst formation associated with chronic corneal edema.

A 39-year-old man with a 3-week history of an enlarging mass protruding from his right cornea is presented. Clinical and pathologic findings were compatible with a large corneal pseudocyst. Causes of corneal cyst and pseudocyst formation, as well as a proposed mechanism for the giant pseudocyst formation presented here, are discussed.

Assessment of MYCN amplification in neuroblastoma biopsies by differential polymerase chain reaction.

Amplification of the oncogene MYCN is a genetic change frequently observed in neuroblastoma and is an indicator of poor prognosis. MYCN copy number is currently determined by Southern blot hybridization. This technique takes 2 to 3 weeks, is labor-intensive, is sensitive to DNA degradation, and requires large quantities of DNA. We have evaluated a new, semiquantitative method of estimating gene copy number that uses differential polymerase chain reaction (PCR). The procedure can be performed in 1 day, is highly reproducible, and requires only nanogram quantities of DNA. It employs a semiquantitative, nonisotopic PCR technique based on differential competition for PCR substrates. MYCN gene primers are amplified together with primers from a single-copy internal control gene. Following electrophoretic separation, the ratio of the two PCR products is determined visually and by densitometric analysis of ethidium bromide-stained agarose gels. This differential ratio is then compared to a series of ratios generated from standards of known MYCN gene copy number. We compared the results obtained by this differential PCR method with those obtained by conventional Southern blotting in 16 cases of primary neuroblastoma. All amplified tumors were detected by differential PCR, and no false positives were observed. We confirmed that differential PCR is a rapid and reliable alternative to Southern blotting for MYCN copy number assessment and is highly suited to the analysis of DNA derived from needle biopsies.