[Retrospective study of 48 cases of primary central nervous system lymphoma]. / Estudio retrospectivo de 48 casos de linfoma primario del sistema nervioso central.

Primary central nervous system lymphoma (PCNSL) is an infrequent form of non-Hodgkin lymphoma restricted to the CNS. More than 90% are type B and mainly affect patients aged 50-70 years. Immunodeficiency is the most important risk factor. The aim of our study was to evaluate the immune status, clinical presentation and findings in complementary studies of PCNSL patients. A retrospective analysis of 48 cases treated in our center between January 1992 and May 2015 was performed. Median age at diagnosis was 61 years (range 25-84); with male predominance (2.1:1). Forty one cases (85%) were immunocompetent patients. Brain MRI findings showed parenchymal involvement in 45 cases (94%), 43% with frontal lobe and 35% basal ganglia, 4% had meningeal involvement and 2% had ophthalmic involvement at diagnosis. Fifty-five percent had restricted signal on diffusion weighted imaging and contrast enhancement was found in 89%. Pyramidal syndrome was the main initial clinical manifestation (56%). There were abnormal findings in 62% of CSF samples, but in only 11.1% positive cytology results were detected. The most frequent type was diffuse large B-cell lymphoma (83%), being B-cell type the most common form between them (96%). In our series PCNSL was more frequent in immunocompetent elderly male subjects. At initial evaluation, clinical manifestations and MRI findings were variable. The initial suspicion of this entity would allow an early diagnosis, avoiding empirical treatments that may confuse or delay diagnosis.

Association Between Lung Immune Prognostic Index and Durvalumab Consolidation Outcomes in Patients With Locally Advanced Non-Small-Cell Lung Cancer.

INTRODUCTION: The LIPI, based on pretreatment derived neutrophils/[leukocytes-neutrophils] ratio (dNLR) and LDH, is associated with immune checkpoint inhibitors (ICI) outcomes in advanced non-small-cell lung cancer (NSCLC). We aimed to assess baseline LIPI correlation with durvalumab consolidation outcomes in the locally advanced setting. MATERIAL AND METHODS: Multicentre retrospective study (330 patients) with stage III unresectable NSCLC treated with durvalumab after chemo-radiotherapy between April 2015 and December 2020; 65 patients treated with chemo-radiotherapy only. Baseline LIPI characterized 3 groups: good (dNLR≤3+LDH≤ULN), intermediate (dNLR>3/LDH>ULN) and poor (dNLR>3+LDH>ULN). Primary endpoint was overall survival (OS). RESULTS: In the durvalumab cohort, median age was 67 years, 95% smokers, 98% with a performance status of 0-1; 60% had nonsquamous histology and 16% a PD-L1 expression <1%. Radiotherapy was delivered concurrently in 81%. LIPI was evaluable in 216 patients: 66% good, 31% intermediate, 3% poor. LIPI significantly correlated with median OS (median follow-up: 19 months): 18.1 months vs. 47.0 months vs. not reached in poor, intermediate and good LIPI groups, respectively (P = .03). A trend between objective response rate and LIPI groups was observed: 0% vs. 41% vs. 45%, respectively (P = .05). The pooled intermediate/poor LIPI group was associated with shorter OS (HR 1.97; P = .03) and higher risk of progressive disease (OR 2.68; P = .047). Survivals and response were not influenced in the control cohort. CONCLUSION: Baseline LIPI correlated with outcomes in patients with locally advanced NSCLC treated with durvalumab consolidation, but not in those who only received chemo-radiotherapy, providing further evidence of its prognostic and potential predictive role of ICI benefit in NSCLC.

Osimertinib and chemotherapy combination to treat brain metastasis flare and osimertinib resistance by EGFR C797S.

Chemotherapy or involvement in a clinical trial remain the standard treatment for patients with EGFR mutant non-small cell lung cancer who have disease progression while receiving Osimertinib. Rapid progression, also known as flare-phenomenon, has been described after discontinuation of tyrosine kinase inhibitors. In this case, we describe a young woman who has extracranial progressive disease due to EGFR C797S resistance mutation while being treated with osimertinib, with a rapid neurological deterioration after osimertinib withdrawal due to flare-phenomenon progression in the brain, and a prompt intracranial response with osimertinib reintroduction in addition to chemotherapy to achieve extracranial diseases control.

Tackling Osimertinib Resistance in EGFR-Mutant Non-Small Cell Lung Cancer.

The current landscape of targeted therapies directed against oncogenic driver alterations in non-small cell lung cancer (NSCLC) is expanding. Patients with EGFR-mutant NSCLC can derive significant benefit from EGFR tyrosine kinase inhibitor (TKI) therapy, including the third-generation EGFR TKI osimertinib. However, invariably, all patients will experience disease progression with this therapy mainly due to the adaptation of cancer cells through primary or secondary molecular mechanisms of resistance. The comprehension and access to tissue and cell-free DNA next-generation sequencing have fueled the development of innovative therapeutic strategies to prevent and overcome resistance to osimertinib in the clinical setting. Herein, we review the biological and clinical implications of molecular mechanisms of osimertinib resistance and the ongoing development of therapeutic strategies to overcome or prevent resistance.

Genomic Landscape of Primary Resistance to Osimertinib Among Hispanic Patients with EGFR-Mutant Non-Small Cell Lung Cancer (NSCLC): Results of an Observational Longitudinal Cohort Study.

BACKGROUND: Epidermal growth factor receptor (EGFR) mutations (EGFRm) represent one of the most common genomic alterations identified among patients with non-small cell lung cancer (NSCLC). Several targeted agents for patients with EGFRm have been proven safe and effective, including the third-generation tyrosine kinase inhibitor (TKI) osimertinib. Nonetheless, some patients will present with or develop EGFR-TKI resistance mechanisms. OBJECTIVE: We characterized the genomic landscape of primary resistance to osimertinib among Hispanic patients with EGFR-mutant NSCLC. METHODS: An observational longitudinal cohort study was conducted with two groups of patients, those with intrinsic resistance (cohort A) and those with long-term survival (cohort B). All patients were treated and followed between January 2018 and May 2022. All patients were assessed for Programmed Cell Death Ligand 1 (PD-L1) expression and Bcl-2-like protein 11 (BIM)/AXL mRNA expression before starting TKI. After 8 weeks of treatment, a liquid biopsy was performed to determine the presence of circulating free DNA (cfDNA), and next-generation sequencing (NGS) was used to identify mutations at the time of progression. In both cohorts, overall response rate (ORR), progression-free survival (PFS), and overall survival (OS) were evaluated. RESULTS: We found a homogeneous distribution of EGFR-sensitizing mutations in both cohorts. For cohort A, exon 21 mutations were more common than exon 19 deletions (ex19dels) for cohort B (P = 0.0001). The reported ORR for osimertinib was 6.3% and 100% for cohorts A and B, respectively (P = 0.0001). PFS was significantly higher in cohort B (27.4 months vs. 3.1 months; P = 0.0001) and ex19del patients versus L858R (24.5 months, 95% confidence interval [CI] 18.2-NR), vs. 7.6 months, 95% CI 4.8-21.1; P = 0.001). OS was considerably lower for cohort A (20.1 months vs. 36.0 months; P = 0.0001) and was better for patients with ex19del, no brain metastasis, and low tumor mutation burden. At the time of progression, more mutations were found in cohort A, identifying off-target alterations more frequently, including TP53, RAS, and RB1. CONCLUSION: EGFR-independent alterations are common among patients with primary resistance to osimertinib and significantly impact PFS and OS. Our results suggest that among Hispanic patients, other variables associated with intrinsic resistance include the number of commutations, high levels AXL mRNA, and low levels of BIM mRNA, T790M de novo, EGFR p.L858R presence, and a high tumoral mutational burden.

Non-small-cell lung cancer: how to manage MET exon 14 skipping mutant disease.

Several oncogenic mechanisms have been identified for MET, including MET amplification, fusions, mutations in the tyrosine kinase domain and exon 14 skipping alterations. MET exon 14 mutations are found in about 3-5% of non-small-cell lung cancers. Dysregulation of the MET receptor leads to cell proliferation and survival by activation of the PI3K-AKT-TOR and RAS-RAF-MET-ERK canonical pathways. Targeting the MET tyrosine kinase domain in the setting of MET exon 14 mutations using effective MET tyrosine kinase inhibitors is a current targeted therapy option for patients with metastatic lung cancer. In this Review, we focus on the management of patients with MET exon 14 skipping alterations by addressing the biology of the MET receptor and exon 14 skipping mutations, current treatment strategies, and sequential treatment options based on resistance mechanisms to MET inhibitors in patients with non-small-cell lung cancer.

Coronavirus Disease 2019 Outcomes, Patient Vaccination Status, and Cancer-Related Delays During the Omicron Wave: A Brief Report From the TERAVOLT Analysis.

Introduction: The Thoracic Centers International coronavirus disease 2019 (COVID-19) Collaboration (TERAVOLT) registry found approximately 30% mortality in patients with thoracic malignancies during the initial COVID-19 surges. Data from South Africa suggested a decrease in severity and mortality with the Omicron wave. Our objective was to assess mortality of patients with thoracic malignancies with the Omicron-predominant wave and evaluate efficacy of vaccination. Methods: A prospective, multicenter observational study was conducted. A total of 28 institutions contributed data from January 14, 2022, to February 4, 2022. Inclusion criteria were any thoracic cancer and a COVID-19 diagnosis on or after November 1, 2021. End points included mortality, hospitalization, symptomatic COVID-19 infection, asymptomatic COVID-19 infection, and delay in cancer therapy. Analysis was done through contingency tables and a multivariable logistic model. Results: We enrolled a total of 346 patients. Median age was 65 years, 52.3% were female, 74.2% were current or former smokers, 86% had NSCLC, 72% had stage IV at time of COVID-19 diagnosis, and 66% were receiving cancer therapy. Variant was unknown for 70%; for those known, Omicron represented 82%. Overall mortality was 3.2%. Using multivariate analysis, COVID-19 vaccination with booster compared with no vaccination had a protective effect on hospitalization or death (OR = 0.30, confidence interval: 0.15-0.57, p = 0.0003), whereas vaccination without booster did not (OR = 0.64, confidence interval: 0.33-1.24, p = 0.1864). Cancer care was delayed in 56.4% of the patients. Conclusions: TERAVOLT found reduced patient mortality with the most recent COVID-19 surge. COVID-19 vaccination with booster improved outcomes of hospitalization or death. Delays in cancer therapy remain an issue, which has the potential to worsen cancer-related mortality.

Mechanisms of Resistance to First-Line Osimertinib in Hispanic Patients With EGFR Mutant Non-Small Cell Lung Cancer (FRESTON-CLICaP).

INTRODUCTION: Osimertinib is a third generation EGFR-TKI inhibitor approved in the first-line setting for patients with advanced non-small cell lung cancer (NSCLC). Additionally, it represents the treatment of choice in patients who present with T790M mutations and evidence of relapse of the disease. Effectiveness and safety of this drug have been studied in multiple clinical trials and observational studies, however, information regarding outcomes among Hispanic patients treated with Osimertinib is scarce. The objective of this study was to examine real-world effectiveness and safety of first-line Osimertinib in a cohort of Hispanic patients with NSCLC, emphasizing post-progression outcomes. METHODS: This is a multicenter, multinational, retrospective cohort study of Hispanic patients treated with Osimertinib as first-line for EGFR-mutated NSCLC. Patients with a confirmed diagnosis of metastatic EGFR-mutated NSCLC who received Osimertinib (80mg/day until evidence of disease progression or presence of intolerable adverse effects) were identified and included. NGS was performed in tumor samples or liquid biopsies among patients who had disease progression. The primary outcome was progression-free survival, and the secondary outcome was post-progression survival. RESULTS: A total of 94 patients from Mexico, Argentina, Costa Rica, Colombia, Panama, Chile and the USA were included, with a median age of 59 years. Identified mutations included EGFR Exon 19 deletions and EGFR pL858R point mutations. Median progression-free survival (PFS) was 14.4 months (95%CI 12.4-18.2 months). Lung/pleura and lymph nodes were the most common sites of progression. Median post-progression survival was 7.73 months (95%CI 4.07 months-Not reached). Factors which negatively affected PFS included presence of liver metastases at diagnosis and a tumor mutational burden > 5 mut/Mb. CONCLUSION: Treatment with first line osimertinib represents an effective and safe option for Hispanic patients with metastatic NSCLC. Liver metastases and a higher tumor mutation burden were associated with a lower PFS. Despite effectiveness, different mechanisms of resistance were identified among the patients in this cohort, including mutations which can be targeted by other therapeutic options.

Durvalumab consolidation in patients with unresectable stage III non-small cell lung cancer with driver genomic alterations.

INTRODUCTION: Durvalumab is the standard-of-care as consolidation therapy after chemo-radiotherapy in stage III unresectable non-small cell lung cancer (NSCLC); however, its activity across patients with NSCLC harbouring driver genomic alterations (dGA) is poorly characterised. MATERIAL AND METHODS: Multicentre retrospective study including patients with stage III unresectable NSCLC treated with durvalumab after chemo-radiotherapy between April 2015 and October 2020 at 26 centres in Europe and America. Clinical and biological data were collected; dGA included: EGFR/BRAF/KRAS mutations (m) and ALK/ROS1 rearrangements (r). We evaluated progression-free survival (PFS) and overall survival (OS) based on dGA. RESULTS: Out of 323 patients included, 43 patients had one dGA: KRASm (n = 26; 8 G12C), EGFRm (n = 8; 6 del19/ex21), BRAFm (n = 5; 4 V600E) and ALKr (n = 4). The median age was 66 years [39-84], gender ratio 1:1, with 98% performance status (PS) 0-1 and 19% non-smokers; 88% had adenocarcinoma. PD-L1 was positive in 85% (n = 4 missing). In the whole cohort, the median PFS was 17.5 months (mo.) (95% CI, 13.2-24.9) and median OS 47 mo (95%CI, 47-not reached [NR]). No statistically significant differences in terms of the median PFS were observed between patients with dGA vs. non-dGA: 14.9 mo (95% CI, 8.1-NR) vs. 18 mo. (95% CI, 13.4-28.3) (P = 1.0); however, when analysed separately: the median PFS was NR (11.3-NR) in the KRASm G12C vs. 8.1 mo (5.8-NR) in the EGFRm del19/ex21 vs. 7.8 mo (7.7-NR) in the BRAFm V600E/ALKr (P = 0.02). CONCLUSIONS: We observed limited activity of durvalumab consolidation in patients with stage III unresectable NSCLC with EGFR/BRAFm and ALKr but not for those harbouring KRASm. Larger prospective studies are needed to confirm these findings.

A Definitive Prognostication System for Patients With Thoracic Malignancies Diagnosed With Coronavirus Disease 2019: An Update From the TERAVOLT Registry.

INTRODUCTION: Patients with thoracic malignancies are at increased risk for mortality from coronavirus disease 2019 (COVID-19), and a large number of intertwined prognostic variables have been identified so far. METHODS: Capitalizing data from the Thoracic Cancers International COVID-19 Collaboration (TERAVOLT) registry, a global study created with the aim of describing the impact of COVID-19 in patients with thoracic malignancies, we used a clustering approach, a fast-backward step-down selection procedure, and a tree-based model to screen and optimize a broad panel of demographics and clinical COVID-19 and cancer characteristics. RESULTS: As of April 15, 2021, a total of 1491 consecutive eligible patients from 18 countries were included in the analysis. With a mean observation period of 42 days, 361 events were reported with an all-cause case fatality rate of 24.2%. The clustering procedure screened 73 covariates in 13 clusters. A further multivariable logistic regression for the association between clusters and death was performed, resulting in five clusters significantly associated with the outcome. The fast-backward step-down selection procedure then identified the following seven major determinants of death: Eastern Cooperative Oncology Group-performance status (ECOG-PS) (OR = 2.47, 1.87-3.26), neutrophil count (OR = 2.46, 1.76-3.44), serum procalcitonin (OR = 2.37, 1.64-3.43), development of pneumonia (OR = 1.95, 1.48-2.58), C-reactive protein (OR = 1.90, 1.43-2.51), tumor stage at COVID-19 diagnosis (OR = 1.97, 1.46-2.66), and age (OR = 1.71, 1.29-2.26). The receiver operating characteristic analysis for death of the selected model confirmed its diagnostic ability (area under the receiver operating curve = 0.78, 95% confidence interval: 0.75-0.81). The nomogram was able to classify the COVID-19 mortality in an interval ranging from 8% to 90%, and the tree-based model recognized ECOG-PS, neutrophil count, and c-reactive protein as the major determinants of prognosis. CONCLUSIONS: From 73 variables analyzed, seven major determinants of death have been identified. Poor ECOG-PS was found to have the strongest association with poor outcome from COVID-19. With our analysis, we provide clinicians with a definitive prognostication system to help determine the risk of mortality for patients with thoracic malignancies and COVID-19.

STK11 and KEAP1 mutations in non-small cell lung cancer patients: Descriptive analysis and prognostic value among Hispanics (STRIKE registry-CLICaP).

BACKGROUND: Mutations in STK11 (STK11Mut) and, frequently co-occurring, KEAP1 mutations (KEAP1Mut) are associated with poor survival in metastatic Non-small Cell Lung Cancer (mNSCLC) patients treated with immunotherapy. However, there are limited data regarding the prognostic or predictive significance of these genomic alterations among Hispanics. METHODS: This retrospective study analyzed a cohort of Hispanic patients (N = 103) diagnosed with mNSCLC from the US and seven Latin American countries (LATAM) treated with immune checkpoint inhibitors (ICI) alone or in combination as first-line (Cohort A). All cases were treated in routine care between January 2016 and December 2021. The main objectives were to determine the association of mutations in STK11 or KEAP1 in these patients' tumors with overall (OS) and progression-free survival (PFS), presence of KRAS mutations, tumor mutational burden (TMB), and other relevant clinical variables. To compare outcomes with a STK11Wt/KEAP1Wt population, historical data from a cohort of Hispanic patients (N = 101) treated with first-line ICI was used, matching both groups by country of origin, gender, and Programed Death-ligand 1 (PD-L1) expression level (Cohort B). RESULTS: Most tumors had mutations only in STK11 or KEAP1 (45.6%) without KRAS co-mutation or any other genomic alteration. Besides, 35%, 8.7%, 6.8%, and 3.9% were KRASMut + STK11Mut, KRASMut + STK11Mut + KEAP1Mut, STK11Mut + KEAP1Mut, and KRASMut + KEAP1Mut, respectively. Based on KRAS status, STK11 alterations were associated with significantly lower PD-L1 expression among those with KRASWt (p = 0.023), whereas KEAP1 mutations were predominantly associated with lower PD-L1 expression among KRASMut cases (p = 0.047). Tumors with KRASMut + KEAP1Mut had significantly higher median TMB when compared to other tumors (p = 0.040). For Cohort A, median PFS was 4.9 months (95%CI 4.3-5.4), slightly longer in those with KEAP1mut 6.1 months versus STK11Mut 4.7 months (p = 0.38). In the same cohort, PD-L1 expression and TMB did not influence PFS. OS was significantly longer among patients with tumors with PD-L1 ≥ 50% (30.9 months), and different from those with PD-L1 1-49% (22.0 months), and PD-L1 < 1% (12.0 months) (p = 0.0001). When we compared the cohorts A and B, OS was significantly shorter for patients carrying STK1 [STK11Mut 14.2 months versus STK11Wt 27.0 months (p = 0.0001)] or KEAP1 [KEAP1Mut 12.0 months versus KEAP1Wt 24.4 months (p = 0.005)] mutations. PD-L1 expression significantly affected OS independently of the presence of mutations in STK11, KEAP1, or KRAS. TMB-H favored better OS. CONCLUSIONS: This is the first large Hispanic cohort to study the impact of STK11 and KEAP1 mutations in NSCLC patient treated with ICI. Our data suggest that mutations in the above-mentioned genes are associated with PD-L1 expression levels and poor OS.

Resistance to KRASG12C Inhibitors in Non-Small Cell Lung Cancer.

KRAS mutations are one of the most prevalent oncogenic alterations in cancer. Until recently, drug development targeting KRAS did not convey clinical benefits to patients. Specific KRASG12C inhibitors, such as sotorasib and adagrasib, have been designed to bind to the protein's mutant structure and block KRASG12C in its GDP-bound inactive state. Phase 1/2 trials have shown promising anti-tumor activity, especially in pretreated non-small cell lung cancer patients. As expected, both primary and secondary resistance to KRASG12C inhibitors invariably occurs, and molecular mechanisms have been characterized in pre-clinical models and patients. Several mechanisms such as tyrosine kinase receptors (RTKs) mediated feedback reactivation of ERK-dependent signaling can result in intrinsic resistance to KRAS target therapy. Acquired resistance to KRASG12C inhibitors include novel KRAS mutations such as Y96D/C and other RAS-MAPK effector protein mutations. This review focuses on the intrinsic and acquired mechanisms of resistance to KRASG12C inhibitors in KRASG12C mutant non-small cell lung cancer and the potential clinical strategies to overcome or prevent it.

Dyskeratosis congenita and a rare brain abscess.

Dyskeratosis congenita is a rare inheritable disease which causes peculiar dermatological features and bone marrow failure with an increased risk of severe infections and neoplasia. Actinomyces spp. is part of the oral cavity flora. Invasive infections are mostly seen in immunocompromised hosts. We report a case of a rare central nervous infection and an underling inheritable disease.

La disqueratosis congénita es una enfermedad hereditaria, caracterizada por alteraciones cutáneas y aplasia medular. La principal causa de muerte son las infecciones y el desarrollo de neoplasias. Actinomices spp. son patógenos comensales de la cavidad oral y el tracto urinario, que en raras ocasiones suelen causar infecciones invasivas en el ser humano. Suelen ser más frecuentes en pacientes inmunocomprometidos o con mala higiene dental. Presentamos el caso de una lesión ocupante de espacio a nivel del sistema nervioso central con una inmunodeficiencia heredable.

Dyskeratosis congenita and a rare brain abscess / Disqueratosis congénita y absceso del sistema nervioso central

Abstract Dyskeratosis congenita is a rare inheritable disease which causes peculiar dermatological features and bone marrow failure with an increased risk of severe infections and neoplasia. Actinomyces spp. is part of the oral cavity flora. Invasive infections are mostly seen in immunocompromised hosts. We report a case of a rare central nervous infection and an underling inheritable disease.

Resumen La disqueratosis congénita es una enfermedad hereditaria, caracterizada por alteraciones cutáneas y aplasia medular. La principal causa de muerte son las infecciones y el desarrollo de neoplasias. Actinomices spp. son patógenos comensales de la cavidad oral y el tracto urinario, que en raras ocasiones suelen causar infecciones invasivas en el ser humano. Suelen ser más frecuentes en pacientes inmunocomprometidos o con mala higiene dental. Presentamos el caso de una lesión ocupante de espacio a nivel del sistema nervioso central con una inmuno deficiencia heredable.

Estudio restrospectivo de 48 casos de linfoma primario del sistema nervioso central / Retrospective study of 48 cases of primary central nervous system lymphoma

Los linfomas primarios del sistema nervioso central (LPSNC) son neoplasias infrecuentes confinadas al SNC. Más del 90% son de tipo B y afectan principalmente a pacientes entre 50-70 años. La inmunodeficiencia es el factor de riesgo más importante. El objetivo de nuestro trabajo fue evaluar las características demográficas, estado inmunológico y los hallazgos en los estudios complementarios de pacientes con LPSNC. Se realizó el análisis retrospectivo de 48 casos estudiados en nuestro centro desde enero 1992 a mayo 2015. La edad mediana de presentación fue 61 años (25-84); la relación hombre:mujer 2.1:1. El 85% (41 casos) fueron inmunocompetentes al momento del diagnóstico. El 94% (45 casos) tuvo compromiso parenquimatoso, 4% (2 casos) meníngeo y 2% (1 caso) ocular. El lóbulo más afectado fue el frontal (43%) y 35% tuvieron compromiso ganglio basal. En RM, el 89% mostró realce con contraste y 55% restricción en difusión. El síndrome piramidal fue la manifestación inicial más frecuente (56%). El LCR fue inflamatorio en el 72%, aunque solo 11.1% presentó examen citológico positivo. El tipo más frecuente de LPSNC fue no-Hodgkin B (96%) y el subtipo difuso de células grandes el más habitual (83%). En nuestra serie la ausencia de inmunocompromiso fue una característica frecuente y la presentación clínico-radiológica fue muy pleomórfica. La sospecha inicial permitiría arribar a un diagnóstico temprano, evitando tratamientos empíricos que puedan confundir o retrasar el diagnóstico.

Primary central nervous system lymphoma (PCNSL) is an infrequent form of non-Hodgkin lymphoma restricted to the CNS. More than 90% are type B and mainly affect patients aged 50-70 years. Immunodeficiency is the most important risk factor. The aim of our study was to evaluate the immune status, clinical presentation and findings in complementary studies of PCNSL patients. A retrospective analysis of 48 cases treated in our center between January 1992 and May 2015 was performed. Median age at diagnosis was 61 years (range 25-84); with male predominance (2.1:1). Forty one cases (85%) were immunocompetent patients. Brain MRI findings showed parenchymal involvement in 45 cases (94%), 43% with frontal lobe and 35% basal ganglia, 4% had meningeal involvement and 2% had ophthalmic involvement at diagnosis. Fifty-five percent had restricted signal on diffusion weighted imaging and contrast enhancement was found in 89%. Pyramidal syndrome was the main initial clinical manifestation (56%). There were abnormal findings in 62% of CSF samples, but in only 11.1% positive cytology results were detected. The most frequent type was diffuse large B-cell lymphoma (83%), being B-cell type the most common form between them (96%). In our series PCNSL was more frequent in immunocompetent elderly male subjects. At initial evaluation, clinical manifestations and MRI findings were variable. The initial suspicion of this entity would allow an early diagnosis, avoiding empirical treatments that may confuse or delay diagnosis.