MEDICINA

La miastenia gravis (MG) es una enfermedad autoinmune de la placa neuromuscular, que se caracteriza por debilidad y fatiga progresivas debido a la existencia de niveles elevados de anticuerpos contra los receptores de acetilcolina o anticuerpos anti-músculo estriado. Ocurre con mayor frecuencia entre la segunda y tercera década de la vida en el sexo femenino, y entre la sexta y séptima en el sexo masculino.

Background: Compare the differences between proteins, glucose, and morphological cellular counts from ventricular cerebrospinal fluid obtained by neuroendoscopy and lumbar puncture. Methods: This was a retrospective, transversal study. From January 2003 until June 2006, 30 neuroendoscopies were performed on patients with hydrocephalus secondary to NCC. Samples of CSF were extracted by lumbar puncture and ventricular neuroendoscopy, and their levels of glucose, proteins, number of leukocytes, and morphological differences (PMN including eosinophiles, monocytes, and lymphocytes) were subsequently measured and studied. Traumatic CSF results were excluded. Twenty-five patients with histopathologic confirmation of the NCC diagnosis were analyzed. The average age of the patients was 42 years (SD, 19.8 years) and female-male ratio was 10:15. Results: The differences in glucose values, between lumbar and ventricular CSF, were not statistically significant-lumbar, 45.28 mg/dL and ventricular, 53.92 mg/dL (P = .129). The differences in the protein values and leukocyte counts were statistically significant (P b .05) with the highest values found in lumbar CSF. The presence of monocytes was higher than that of PMNs in both fluids (P b .05). We did not find eosinophiles in any CSF. Conclusions: We did not find differences in the glucose values as described by previous studies, but our findings showed differences in the values of proteins, PMN leukocytes, and monocytes. The presence of more monocytes could be explained by their incremented activation by the parasite antigen and chronicity of the disease. Translational trials with uniform criteria are needed to determinate the immune process in the several presentations of the disease in humans.

Background: An early virological response to interferona treatment is a strong predictor of sustained response, but it has never been exploited to stratify patients in clinical trials. Aim: To evaluate the efficacy of amantadine plus interferon-a compared with interferon-a alone in naive patients with chronic hepatitis C who were randomized on the basis of the early virological response to interferon-a. Methods: One hundred and eighty-one patients received recombinant interferon-a2a (3 MU three times weekly) for 2 months and 164 were evaluated for early (i.e. month 2) virological response. Hepatitis C virus (HCV) RNA-negative patients (n ¼ 66) were randomized to receive 3 MU of interferon-a three times weekly, with or without amantadine (200 mg/day); HCV RNA-positive patients (n ¼ 98) were randomized to receive 6 MU of interferon-a three times weekly, with or without amantadine (200 mg/day). HCV RNA-positive patients at 6 months discontinued treatment, and all others completed 12 months. Results: At month 6, HCV RNA-negative patients made up 54.2% of the interferon + amantadine group and 42.0% of the monotherapy group (P ¼ 0.07). At month 12, HCV RNA-negative patients made up 38.5% of the interferon + amantadine group and 28.4% of the monotherapy group (N.S.). The sustained virological response rates were 21.6% and 20.9%, respectively (N.S.). Conclusion: The addition of amantadine does not enhance the sustained virological response to interferon-a in naive patients with chronic hepatitis C; however, an additive effect of amantadine occurs in the first 6 months, mainly in patients without an early response to monotherapy. Early response to interferona is a strong predictor of sustained virological response.

Early virological response to antiviral treatment is a strong predictor of sustained response, yet it is not used to stratify patients in clinical trials. Aim of this study was to compare efficacy and safety of mono-versus combination therapy in patients who achieved early viral clearance (EVC) on peginterferon alpha-2a 40kD (PEG-IFN) monotherapy. Two-hundred-eight naive patients (159 males; median age, 42 years) with chronic hepatitis C (genotype 1,4: 62%) completed 12 weeks of PEG-IFN treatment, 180 mg qw. One-hundred-twenty-one (58%) achieved EVC, defined as undetectable HCV RNA (<50 IU/ml) by qualitative PCR (Amplicor, Roche) and were randomized to continue PEG-IFN monotherapy or to add ribavirin (RBV) 800 mg/day, for 12 additional weeks: 64 patients received PEG-IFN monotherapy, while 57 patients received combination therapy (PEG-IFN + RBV). Qualitative HCV RNA at 24 weeks is available in 83 patients (44 and 39, respectively): 39 (88.6%) in the monotherapy group vs 37 (94.8%) in the combination therapy group remained HCV RNA negative (ns). Between weeks 12 and 24 there were 2 drop-outs in the monotherapy and 5 in the combination group and a similar number of dose reductions. HCV RNA negative patients at week 24 are continuing treatment for a total of 48 weeks. Conclusion: In patients who achieve early viral clearance, continuing PEG-IFN monotherapy results in similar rates of viral clearance at 24 weeks compared to PEG-IFN plus ribavirin. These preliminary data suggest that, in this subgroup of easy-to-treat naïve patients, monotherapy may be as effective as combination therapy.

Background: Adjuvant chemotherapy is not indicated in lymph node-negative colorectal adenocarcinoma (CRC), even though some cases will present recurrent disease. It is important to identify a subgroup of patients with the highest risk of relapse because of the potential benefit of adjuvant chemotherapy. The objective of this study is to define the prognostic factors and describe a method for the selection of this subgroup. Methods: A retrospective cohort of 124 patients with lymph node-negative CRC with complete surgical resection was studied. Cox's proportional hazards model was used to define the prognostic factors associated with CRC-related survival and to develop a method for prediction of recurrence probability. Results: The cohort included 62 women and 62 men with mean age 55.8 years. The mean follow-up period was 11.7 years. T classification of the primary tumor, differentiation grade, carcinoembryonic antigen level, gender and the presence of neural invasion were significant prognostic factors according to the multivariate analysis (final model P = 0.00001). Using risk ratios for these prognostic factors, we defined a high-risk group of 78 patients and a low-risk group of 46 patients with 24 and 5 recurrences, respectively (recurrence rates of 30.8% and 10.9% respectively, P = 0.011). Conclusions: Using these factors, a prognostic scale was developed to predict high risk of recurrence in cases of completely resected CRC and to identify them as a subgroup of patients with potential benefit of adjuvant chemotherapy.

Melasma is an acquired hypermelanosis on sun-exposed areas. Its pathogenesis has not been clearly elucidated. Using histochemistry (Giemsa, Verhoeff–van Gieson and Fontana–Masson staining), we evaluated melasma lesions and compared them with nonlesional skin. Skin samples were obtained from lesional and nonlesional facial skin of 27 patients with melasma, and biopsies were also taken from normal control subjects. Mast cells and solar elastosis areas were evaluated using a computer-assisted image-analysis program. Lesional skin had abundant elastotic material compared with nonaffected skin (13.3 ± 2.8% vs. 10.2 ± 2.9%, P < 0.001). Mast cells were more prominent in the elastotic areas of melasma skin (173 ± 57% vs. 145 ± 57%, P = 0.04). Melasma could be a result of a cumulative sun exposure, in a microenvironment of cutaneous photoageing in which inflammatory cells, particularly mast cells, play a key role.

background:Cutaneous malignant melanoma is a common and frequently lethal neoplasm with increasing worldwide incidence. It metastasizes thorough dermal blood and lymphatic vessels. The induction of angiogenesis by the tumor provides another possible explanation
for tumor extension.
Objectives:To determine the density of lymphatic vessels in samples of cutaneous melanoma and make a correlation with positive lymph
node metastasis.
Material and methods: A retrospective, descriptive study was made using the last 10 cases of melanoma cutaneous biopsies searching
for Clark and Breslow level, inflammation, mitosis and lymphatic vessels and regional lymph node invasion.
Results:The lymphatic vessel density was higher in positive lymph node in comparison with negative lymph node.
Conclusion:The lymphangiogenesis is a novel prognostic indicator for the risk of lymph node metastasis in cutaneous melanoma.
Key words:cutaneous melanoma, lymphatic vessel density, lymphangiogenesis.

Schwannoma is a benign neurogenic tumor of slow growing. Fourty-five percent of cases occur in head and neck region; its origin on
nasal cavity and paranasal sinuses is not common, about 4%. We
report the case of a nasal septum schwannoma in a male 68 year-old
patient, with a tumor of eight years of evolution with clinical signs of
nasal obstruction and rhinorrhea. Extirpation by lateral rhynotomy
was done successfully. After three years of follow-up patient does
not have recurrence.

Background:Axillary hyperpigmentation is a frequent cause of cosmetic consultations in
dark-skinned women from tropical areas, including Latin America. Currently, there is no widely
accepted treatment for the disorder, but it is usually treated with bleaching agents because it
is considered a variant of inflammatory hyperpigmentation. The purpose of this study was to
assess the efficacy of niacinamide 4% and desonide 0.05% emulsions compared with placebo
in the treatment of axillary hyperpigmentation.
Methods:Twenty-four women aged 19–27 years with hyperpigmented axillae (phototype III–V)
were randomly assigned to receive the study treatments in the axillary region. Improvement was
assessed at baseline, then clinically and by colorimetry 9 weeks later. Quantitative evaluation
including melanin, inflammatory infiltrates, NKI/Beteb, CD1a, CD68, and collagen type IV
content was performed by histochemistry and immunohistochemistry, assisted by computerized
morphometric analysis.
Results:Both niacinamide and desonide induced significant colorimetric improvement compared
with placebo; however, desonide showed a better depigmenting effect than niacinamide. A good to
excellent response was achieved in 24% of cases for niacinamide, 30% for desonide, and 6% for
placebo. We observed a marked disruption of the basal membrane in axillary  hyperpigmentation
and  an  inflammatory  infiltrate  that  improved  after  treatment.  Decreased  pigmentation  in  the
desonide-treated axillae was associated with recovery of disruption at the basal membrane.
Conclusion: Niacinamide  and  desonide  showed  depigmenting  properties  in  women  with
axillary hyperpigmentation. These findings may be explained by their antimelanogenic and
anti-inflammatory properties, respectively.
Keywords:post-inflammatory hyperpigmentation, niacinamide, desonide

Summary
The twenty-fourth case of primary renal angiosarcoma is
described, according to the available internacional literature,
this present in a 71-year-old male, a mechanic by trade, without
carcinogenic antecedents. Hematuria, pain in flank, and leftside tumoral mass of approximately 20 cm in diameter located
in kidney by computerized axial tomography (CT) constituted
manifestations. A left nefrectomy was performed. No metastasis
was found.
The tumor replaced 4/5 of the organ and weighed 1145 g. It
showed angiomatous structure with atypical proliferation of
endothelial cells in a sinusoldal trauma and anastomosatic
vascular channels that invaded neighboring parenchymal and
capsule. Tymorous cells were positive for CD31 and CD34 and
negative for cytokeratins, S100 and HMB 45 proteins.
The patient was subjected to treatment with chemotherapy
and radiotherapy (lineal accelerator), but 12 months after
surgery he presented retroperitonal tumoral relapse and
hepatic metastasis.
Diagnostic differentiation with benign vascular tumors is
pointed out, as well as carcinomas and sarcomas that showed
an outstanding angiomatous component, both primary and/or
secondary.
Primary renal angiosarcoma exposes the multiplicity of
localizations that it is capable of with a tumor of this type, as
well as renal parenquimatous capacity to be the seat of a
great variety of neoplasias.
Key words:Angiosarcoma, kidney.

Resumen El schwannoma es un tumor neurogénico benigno de crecimiento lento. El 45% de los casos ocurren en la región de la cabeza y el cuello; su origen en la cavidad nasal y los senos paranasales es poco común: aproximadamente 4%. Se comunica el caso de un schwan-noma del tabique nasal en un paciente de 68 años de edad, con una tumoración de ocho años de evolución que clínicamente mostraba sólo obstrucción nasal y rinorrea. Se realizó extirpación por abordaje de rinotomía lateral, con éxito. Luego de tres años de seguimiento no muestra recurrencia. Abstract Schwannoma is a benign neurogenic tumor of slow growing. Four-ty-five percent of cases occur in head and neck region; its origin on nasal cavity and paranasal sinuses is not common, about 4%. We report the case of a nasal septum schwannoma in a male 68 year-old patient, with a tumor of eight years of evolution with clinical signs of nasal obstruction and rhinorrhea. Extirpation by lateral rhynotomy was done successfully. After three years of follow-up patient does not have recurrence.

Hypercalcemia in children with malignancy is an uncommon condition. It has been described in leukemia patients with impaired renal excretion of calcium or osteolytic lesions. Metastatic calcinosis cutis (MCC) may develop if hypercalcemia persists. We report the case of a 5-year-old girl with an atypical dermatosis and unspecific gastrointestinal symptoms. Considered clinical diagnoses were xanthomas, histiocytosis, molluscum contagiosum, and nongenital warts. Cutaneous histological analysis showed amorphous basophilic deposits in the dermis suggestive of calcium deposits. Laboratory tests confirmed serum hypercalcemia. Extensive investigations such as bone marrow biopsy established the diagnosis of an acute pre-B cell lymphoblastic leukemia. Hypercalcemia in hematopoietic malignancies is unusual, especially as initial manifestation of the disease. Careful review of the literature fails to reveal previous reports of these peculiar cutaneous lesions of MCC in children with leukemia.

Purpose: To improve the quality of cervical screening done by nursing interns. Methods: A quasi-experimental, longitudinal, prospective study. A non-probability sampling was applied for convenience. 23 interns participated in a public institution from San Luis Potosi, México, in the period from February to June 2015. The training was divided into three phases: I).-baseline measurement, II).–Training and III).-Final measurement with a total of 48 hours. A test of knowledge and two checklists was applied; one for assessing practical skills in taking cervical smears and another to measure the quality of the samples before and after training. For data analysis Student's t test, analysis of variance with repeated measures and analysis Binomial was used. Results: A statistically significant difference in average knowledge (t =-12,804 p = .000) and practical skills (t =-8862 p = .000) was obtained after training. The percentage of adequate specimens increased from 30.43% to 82.60% finding a statistically significant difference (p=.000). Conclusions: The training is effective in improving the knowledge and practical skills as well as the quality of the samples for interpretation.