RESUMO

Introduction: schwannomas are benign and common soft tissue tumors. They are usually asymptomatic and are discovered for other reasons. Materials: we present the case of an 82-year-old male patient with a recent diagnosis of moderately differentiated adenocarcinoma of the colon and a hypermetabolic periaortic nodule as an incidental finding. Results: percutaneous biopsy of the periaortic nodule confirmed the diagnosis of schwannoma. At one year of follow-up, growth of the schwannoma has been demonstrated. There are no signs of progression of his oncological disease. Conclusions: schwannomas are benign tumors, rarely found in the retroperitoneum and can be sources of false-positive positron emission tomography results.

Introducción: los schwannomas son tumores benignos y frecuentes de las partes blandas. Habitualmente son asintomáticos y son descubiertos por otros motivos. Materiales y métodos: presentamos el caso de un paciente masculino de 82 años con diagnóstico reciente de adenocarcinoma de colon moderadamente diferenciado y con un nódulo periaórtico hipermetabólico como hallazgo incidental. Resultados: la biopsia percutánea del nódulo periaórtico confirmó el diagnóstico de schwannoma. Al año de seguimiento, se ha demostrado crecimiento del schwannoma. No hay signos de progresión de su enfermedad oncológica. Conclusión: los schwannomas son tumores benignos, infrecuentes en el retroperitoneo y pueden ser fuentes de resultados falsos positivos en tomografía por emisión de positrones.

Assuntos

RESUMO

Resultados falsos positivos na mamografia de rastreamento são comuns a essa intervenção e trazem ônus para as mulheres e o sistema de saúde. O objetivo deste estudo foi estimar o risco de resultado falso positivo no rastreamento mamográfico brasileiro com base em dados de sistemas de informação do Sistema Único de Saúde (SUS). Foi realizado estudo de coorte histórica de mulheres de 40-69 anos, que realizaram mamografia de rastreamento e exame histopatológico de mama no SUS, nos anos de 2017 a 2019. A taxa de resultados falsos positivos foi estimada a partir da prevalência de resultados BI-RADS alterados na mamografia de rastreamento e da proporção de resultados benignos no exame histopatológico de mama. Das 10.671 mulheres com exame histopatológico no SUS, 46,2% apresentaram resultado benigno, sendo essa proporção significativamente maior em mulheres de 40-49 anos comparada à de mulheres de 50-69 anos. A estimativa de resultados falsos positivos foi de 8,18 casos por 100 mulheres na faixa etária de 40-49 anos, e de 6,06 por 100 mulheres na faixa de 50-69 anos. Essas informações são úteis aos gestores na avaliação de programas de rastreamento do câncer de mama, assim como aos profissionais de saúde, para que orientem a mulher sobre as implicações do rastreamento mamográfico.

False-positive results on mammography screening are common, putting a burden on both women and the health care system. This study aimed to estimate the risk of false-positive results in Brazilian mammography screening based on data from the Brazilian Unified National Health System (SUS) information systems. A retrospective cohort study was conducted with women aged 40-69 years, who underwent mammography screening and breast histopathological examination at SUS from 2017 to 2019. The rate of false-positive results was estimated based on the prevalence of altered BI-RADS results on mammography screening and the proportion of benign results on breast histopathological examination. Of the 10,671 women with histopathological examination at SUS, 46.2% had a benign result, and this proportion was significantly higher in women aged 40-49 years compared to women aged 50-69 years. The estimate of false-positive results was 8.18 cases per 100 women aged 40-49 years and 6.06 per 100 women aged 50-69 years. This information is useful for public managers in evaluating mammography screening programs, as well as for health care providers to guide women on the implications of mammography screening.

Los resultados falsos positivos en la mamografía de cribado son comunes en esta intervención y suponen prejuicios para las mujeres y el sistema de salud. El objetivo de este estudio fue estimar el riesgo de resultados falsos positivos en el cribado mamográfico brasileño a partir de los datos del sistema de información del Sistema Único de Salud (SUS). Se realizó un estudio de cohorte histórica de mujeres de 40-69 años, que se sometieron a mamografía de cribado y examen histopatológico de mama en el SUS, de 2017 a 2019. La tasa de resultados falsos positivos se estimó a partir de la prevalencia de resultados de BI-RADS alterados en la mamografía de cribado y la proporción de resultados benignos en el examen histopatológico de mama. De las 10.671 mujeres que se sometieron a examen histopatológico en el SUS, el 46,2% tuvo un resultado benigno, siendo esta proporción significativamente mayor en mujeres de 40-49 años en comparación con las mujeres de 50-69 años. La estimación de resultados falsos positivos fue de 8,18 casos por 100 mujeres en el grupo de edad de 40-49 años y 6,06 por 100 mujeres en el grupo de 50-69 años. Esta información es útil para los gestores en la evaluación de los programas de cribado de cáncer de mama, así como para los profesionales sanitarios en orientar a las mujeres sobre las implicaciones del cribado mamográfico.

RESUMO

RESUMEN El manejo de las infecciones virales respiratorias, tanto a nivel nacional como a nivel mundial, requiere resultados científicos de calidad. La reacción en cadena de la polimerasa de transcriptasa inversa (rRT-PCR, por su sigla en inglés) es considerada el "patrón de oro" para detectar el genoma del nuevo coronavirus 2 (SARS-CoV-2), agente causal de la enfermedad por el nuevo coronavirus (COVID-19) sobre todo en la fase aguda de la infección. Su uso es controvertido fuera de un contexto de exposición viral. El objetivo del presente trabajo es analizar escollos encontrados durante la detección del genoma del SARS-CoV-2 que pueden producir resultados falsos. Los falsos negativos de rRT-PCR pueden deberse al momento y la eficacia de la toma de la muestra, la congelación, el almacenamiento y la descongelación, y a la inactivación térmica de la virulencia. Además, las señales retardadas de los controles internos invalidan la negatividad. Por otra parte, las muestras con escaso material biológico llevan a conclusiones negativas falsas, por lo que determinar un umbral (número mínimo de células epiteliales) contribuirá a reducirlas. Sin embargo, la mayoría de los kits detectan ADN humano, pero no fueron calibrados para cuantificar carga celular. Los ácidos ribonucleicos nucleares (ARN) virales adheridos a guantes, tubos y gorros, -entre otros elementos-, son fuente de falsos positivos. Las farmacopeas sugieren que la contaminación externa se controle en series de 100 muestras con al menos una representatividad del 10%. Si se extrapola esta aproximación al laboratorio de análisis clínicos, en lugar de uno se deberían procesar al menos 10 controles negativos contiguos a 10 positivos cada 100 pruebas. Mejorar la detección por rRT-PCR implica un aumento de al menos 20% en el costo de los reactivos, por lo que se necesitan recursos adicionales.

ABSTRACT Emerging respiratory viral infections like the severe coronavirus disease (CoVID 19) caused by novel coronavirus 2 (SARS-CoV-2) require quality results for science-based responses. The reverse transcriptase polymerase chain reaction (rRT-PCR) is considered the gold standard for detecting SARS-CoV-2 (particularly in the acute phase of infection). The aim of the present work was to analyze pitfalls during the search of viral genomes. False negative conclusions are result of sampling timing, performances of swabbing, storage, and thawing and heat-infectivity inactivation. Samples with low biologic material also lead to false negatives. Qualitative controls to detect the presence of human DNA are available in several kits but they were not calibrated for quantification of human cell loads. Moreover, negativity cannot be reported for samples with delayed signals for the internal control (due to deficiency in extraction and/or retro transcription and/or or to the presence of rRT-PCR inhibitors). The viral RNA that may have stick on gloves, on tubes, caps, etc. may produce false positives. The International Pharmacopoeias recommend for external contamination to test at least 10% of the samples. Couples of 10 negative contiguous to 10 positive controls randomly distributed should be therefore included in each series of 100 rRT-PCR tests. These improvements increase the cost of each determination (at least by 20% only for the reactants) and require additional resources.

RESUMO

OBJECTIVES: To verify the incidence of facetary and low back pain after a controlled medial branch anesthetic block in a three-month follow-up and to verify the correlation between the positive results and the demographic variables. METHODS: Patients with chronic lumbar pain underwent a sham blockade (with a saline injection) and then a controlled medial branch block. Their symptoms were evaluated before and after the sham injection and after the real controlled medial branch block; the symptoms were reevaluated after one day and one week, as well as after one, two and three months using the visual analog scale. We searched for an association between the positive results and the demographic characteristics of the patients. RESULTS: A total of 104 controlled medial branch blocks were performed and 54 patients (52%) demonstrated >50% improvements in pain after the blockade. After three months, lumbar pain returned in only 18 individuals, with visual analogue scale scores >4. Therefore, these patients were diagnosed with chronic facet low back pain. The three-months of follow-up after the controlled medial branch block excluded 36 patients (67%) with false positive results. The results of the controlled medial branch block were not correlated to sex, age, pain duration or work disability but were correlated with patient age (p<0.05). CONCLUSION: Patient diagnosis with a controlled medial branch block proved to be effective but was not associated with any demographic variables. A three-month follow-up is required to avoid a high number of false positives. .

Assuntos

RESUMO

Bartonella henselae was detected in defibrinated sheep blood employed in supplementing a selective bacteria culture medium by nested PCR. We recommended that highly sensitive technical tests be run to ensure a sterile culture medium for Bartonella spp. isolation, since infected blood samples used in preparation could lead to false-positive results.

RESUMO

Bartonella henselae was detected in defibrinated sheep blood employed in supplementing a selective bacteria culture medium by nested PCR. We recommended that highly sensitive technical tests be run to ensure a sterile culture medium for Bartonella spp. isolation, since infected blood samples used in preparation could lead to false-positive results.

RESUMO

Bartonella henselae was detected in defibrinated sheep blood employed in supplementing a selective bacteria culture medium by nested PCR. We recommended that highly sensitive technical tests be run to ensure a sterile culture medium for Bartonella spp. isolation, since infected blood samples used in preparation could lead to false-positive results.

RESUMO

In Guadeloupe, a Caribbean island with a high prevalence of HTLV-I infected subjects, the percentage of false positive results for HIV IgG is high, requiring additional time and expense for confirmatory tests. This article describes a simple way of overcoming this problem. First, all IgG and IgG immune complexes are removed by protein G treatment, and then IgA enzyme-linked immunosorbent assay (ELISA) and the Western blot test are performed with minor modification of commercially available kits.

PIP: Researchers wanted to determine whether they could do a more specific ELISA HIV test directed at IgA rather than IgG antibodies. So they 1st used streptococcal protein G to remove IgG from serum samples of 10 follow up patients from Guadeloupe who previously tested positive via ELISA for HIV-1/2 IgG and HTLV-I IgG. They did this to test sera for IgA. The protein G treatment resulted in a 99.9% reduction in the IgG concentration (12.21.7 mg/ml to .007-.017 mg/ml). After IgG depletion, the researchers noted no ELISA positive samples for HIV-1/2 or HTLV-I IgG. In fact, all the values were well below the cutoff levels. This result indicated that streptococcal protein G treatment followed by IgA ELISA is more specific than testing for IgG. The sera of 8 patients tested negative for HIV-1/2 IgA, but all tested positive for HTLV-1 IgA. This result showed that IgA may be more useful than IgG for also confirming retroviral infections. The sera of 2 patients were 44% and 27% above the cutoff level indicating that these patients had HIV-1/2 IgA antibodies. The researchers observed that protein G treatment suppressed all HIV-1/2 and HTLV-I IgG Western blot reactivity which confirmed the effectiveness of protein G treatment. Further the HIV IgG bands in the 8 false positive sera did not materialize at all suggesting that the IgG reactivity observed was most likely nonspecific. These results indicated that nonspecific HIV-1/2 IgG caused the false positive HIV-1/2 IgG ELISA results. In conclusion, in Caribbean countries where HTLV-1 infection can be as high as 13%, the more specific HIV IgA ELISA test should be used since its use saves time and money. Further it can do generalized testing for HTLV antibodies.

Assuntos

RESUMO

Sera from 472 Brazilian subjects, confirmed to be either positive or negative for HIV antibodies and comprising the total clinical spectrum of HIV infection, were utilized in the evaluation of six commercially available enzyme-linked immunosorbent assays (ELISA), as well as of four alternative assays, namely indirect immunofluorescence (IIF), passive hemagglutination (PHA), dot blot and Karpas AIDS cell test. The sensitivities ranged from 100% (Abbott and Roche ELISA) to 84.2% (PHA) and the specificities ranged from 99.3% (IIF) to 80.2% (PHA). The sensitivity and specificity of the PHA and the sensitivity of the Karpas cell test were significantly lower than those of the other tests. Although the IFF and dot blot had good sensitivities and specificities, the six ELISA were more attractive than those tests when other parameters such as ease of reading and duration of assay were considered.

PIP: 6 commercially available ELISA kits and 4 new Brazilian made methods for detecting HIV were compared on 2 panels of sera, 292 from AIDS patients, HIV-positives and negatives, and 180 sera from asymptomatic blood donors, including 90 HIV-positives. The kits tested were 5 ELISAs: Roche Diagnostica (Basel), Hoechst Enzygnostic (Sao Paulo), Virgo Electronuclionics (Columbia MD), Organon Teknika (Boxtel, Netherlands), Salck Industria e Comercio de Produtos Biologicos (Sao Paulo), and a passive hemagglutination test, (Salck Ind), and indirect immunofluorescence IIF (Virgo electronucleonics, Columbia), a dot blot (Embrabio, Empressa Brasiliera de Biotecnologia Ltda, Sao Paolo) and Karpas AIDS cell test, Fujichemical Industries Ltd (Chokeiji, Takaoka, Japan). The sensitivities ranged from 84.2% to 100% with no significant differences in sera from panel A. In panel B, the sensitivity of the PHA test was significantly lower than that of the ELISA and the AIDS cell tests. The specificities of the PHA and the AIDS cell tests were also lower than that of the ELISA. The costs of all the tests were similar, but the equipment needs varied. The simplest tests to perform were the dot blot assay, PHA and Karpas AIDS cell test. The Hoechst ELISA is simpler because it does not require dilution of the serum. The dot takes too long for use in a blood bank, 16-18 hours. Immunofluorescence tests would be practical in countries already screening blood for malaria or Changes disease. Brazil is not doing so on a large scale due to lack of political will. In countries with high incidence of malaria, Chagas disease, leishmania, hepatitis and leprosy, HIV test need to be tested on local sera because of possible B cell activation.

Assuntos