Linfocitosis monoclonal de células B en familiares de pacientes colombianos con síndromes linfoproliferativos crónicos B / B-cell lymphocytosis in relatives of Colombian patients with chronic B-cell lymphoproliferative disorders

Introducción. La linfocitosis monoclonal de células B, generalmente, precede la leucemia linfocítica crónica y afecta alrededor del 12 % de la población adulta sana. Esta frecuencia se incrementa en familiares de pacientes con síndromes linfoproliferativos crónicos de células B. Objetivo. Determinar la frecuencia de linfocitosis monoclonal B en familiares de pacientes con síndromes linfoproliferativos crónicos B, sus características inmunofenotípicas y citogenéticas, posible relación con agentes infecciosos, y seguimiento a corto plazo de población colombiana. Materiales y métodos. Se estudiaron 50 adultos sanos con antecedentes familiares de síndromes linfoproliferativos crónicos de célula B, empleando citometría de flujo multiparamétrica, pruebas citogenéticas y serológicas, encuesta de hábitos de vida y seguimiento a dos años. Resultados. La frecuencia encontrada de linfocitosis monoclonal B fue del 8 %, con predominio del sexo femenino y edad avanzada, incrementándose al 12,5 % en individuos con antecedentes familiares de leucemia linfocítica crónica. Tres de cuatro individuos presentaron inmunofenotipo de tipo leucemia linfocítica crónica, todas con bajo recuento. A su vez, en estos individuos se observa de manera significativa un mayor número de células/µl en subpoblaciones linfocitarias T, junto con mayor predisposición a la enfermedad. Las poblaciones clonales descritas aumentan a lo largo del tiempo de manera no significativa. Conclusiones. La frecuencia y comportamiento de la linfocitosis monoclonal de célula B en pacientes con antecedentes familiares de síndromes linfoproliferativos crónicos B es similar a lo encontrado en estudios relacionados,lo que sugiere que no existe afectación degenes de mayor relevancia que puedan desencadenar una proliferación clonal descontrolada, pero que generan desregulación inmunológica que podría indicar un mayor riesgo de infección grave en estos individuos.

Introduction. Monoclonal B-cell lymphocytosis generally precedes chronic lymphocytic leukemia, affecting about 12% of the healthy adult population. This frequency increases in relatives of patients with chronic B-cell lymphoproliferative disorders. Objective. To determine the frequency of monoclonal B-cell lymphocytosis in relatives of patients with chronic B-cell lymphoproliferative disorders, their immunophenotypic/cytogenetic characteristics, a possible relationship with infectious agents, and short-term follow-up in the Colombian population. Materials and methods. Fifty healthy adults with a family history of chronic B-cell lymphoproliferative disorders were studied using multiparametric flow cytometry, cytogenetic/serological testing, lifestyle survey, and 2-year follow-up. Results. The frequency of monoclonal B-cell lymphocytosis found was 8%, with a predominance of female gender and advanced age, increasing to 12.5% for individuals with a family history of chronic lymphocytic leukemia. Three out of four individuals presented chronic lymphocytic leukemia-type immunophenotype, all with low counts. In turn, a significantly higher number of cells/µl is observed in these individuals in T lymphocyte subpopulations, together with a greater predisposition to the disease. The described clonal populations increase over time in a non-significant manner. Conclusions. The frequency and behavior of monoclonal B-cell lymphocytosis in patients with family history of chronic B-cell lymphoproliferative disorders are like those found in related studies, which suggests that there is no involvement of more relevant genes that can trigger uncontrolled clonal proliferation, but that generates immunological deregulation that could justify a greater risk of serious infection in these individuals.

Leucemia linfocítica crónica y deleción del gen TP53: reporte de un caso y revisión de la literatura / Chronic lymphocytic Leukemia and deletion of the TP53 gene: Case report and literature review

RESUMEN Las alteraciones genéticas en el gen TP53 están presentes entre el 5 al 8 % de los pacientes de leucemia linfocítica crónica (LLC) en el momento del diagnóstico. Estos casos se relacionan con un mal pronóstico debido a su resistencia al tratamiento estándar. Presentamos el caso de un paciente masculino de 52 años diagnosticado con LLC, expresión del marcador CD38 y una deleción en el gen TP53 (17p13.1). Tras la evaluación posterior del tratamiento, se observó enfermedad mínima residual lo que llevó a un trasplante haploidéntico de progenitores hematopoyéticos. Debido al alto riesgo de recaída, su edad y la ausencia de comorbilidades, era la única opción curativa hasta la fecha para la LLC. El objetivo de este trabajo es realizar una revisión de la literatura que sirva como base para analizar el caso clínico presentado, en el marco de las implicaciones clínicas, pronóstico y respuesta al tratamiento en los individuos con LLC que presentan alteraciones en el gen TP53.

SUMMARY Genetic alterations in the TP53 gene are present in 5 to 8% of chronic lymphocytic leukemia (CLL) cases at the time of diagnosis. These cases are typically associated with poor prognosis due to their resistance against standard CLL treatment. In our report a 52-yearold male patient was diagnosed with CLL, CD38 expression and a deletion in the TP53 gene (17p13.1). Upon evaluation post-treatment, minimal residual disease (MDR) was observed, and a haploidentical stem cell transplant was performed. Because of the high risk of relapse, his age, and the absence of comorbidities it was the only curative option to date for CLL. The purpose of this article is to complete a literature review that will give a basis to analyze the clinical case presented, within the framework of the clinical implications, prognosis, and response to treatment in patients with CLL who present with aberrations of the TP53 gene.

Potasio elevado, sin T picuda / High pot but no T

Introducción. La identificación y el tratamiento de pacientes con hiperpotasemia son necesarios para prevenir el desarrollo de arritmias. La pseudohiperpotasemia se debe más comúnmente a la hemólisis de la muestra y a menudo es reconocida por los laboratoristas que posteriormente informan los resultados de las pruebas con advertencias de precaución. Los autores presentan un caso de pseudohiperpotasemia en un paciente con leucemia linfocítica crónica. Reporte de caso: los factores técnicos y el método de transporte son una causa potencial de pseudohiperpotasemia. La pseudohiperpotasemia se ha asociado también con hiperleucoctosis, en poblaciones de pacientes con cáncer, más comúnmente en Leucemia linfocítica crónica en adultos, pero también con leucemia linfoblástica aguda en niños. Esto pone al paciente en riesgo de tratamientos innecesarios y potencialmente peligrosos. Conclusión: Los médicos deben considerar la pseudohiperpotasemia como la causa subyacente de los niveles elevados de potasio en pacientes con leucocitosis maligna que no presentan signos o síntomas de hiperpotasemia sistémica.

Introduction. The identification and treatment of patients with hyperkalemia is necessary to prevent the development of arrhythmias. Pseudohyperkalemia is most commonly due to specimen haemolysis and is often recognised by laboratory scientists who subsequently report test results with cautionary warnings. The authors present a case of pseudohyperkalemia in a patient with chronic lymphocytic leukaemia. Report case: the technical factors and method of transport are a potential cause of pseudohyperkalemia. Pseudohyperkalemia has been associated with hyperleukoctosis, in cancer patient populations, more commonly in CLL in adults, but also acute lymphoblastics leukemia in children. This places the patient at risk of unnecessary and potentially dangerous treatments. Conclusion: Physicians should consider pseudohyperkalemia as the underlying cause of elevated potassium levels in patients with malignant leucocytosis who do not have signs or symptom of systemic hyperkalemia.

Acquired reactive perforating collagenosis in association with prostate adenocarcinoma, chronic lymphocytic leukemia, and Graves disease

Abstract Acquired reactive perforating collagenosis is a rare skin disorder characterized by the presence of umbilicated pruritic papules and nodules. Transepidermal elimination of altered and perforating bundles of basophilic collagen from the epidermis is a characteristic histologic feature of acquired reactive perforating collagenosis. Along with its well-known association with systemic diseases such as diabetes mellitus, chronic renal failure, and dermatomyositis, there are reports of acquired reactive perforating collagenosis being associated with malignancies. Herein, we present a case of acquired reactive perforating collagenosis associated with chronic lymphocytic leukemia, prostate adenocarcinoma, and Graves's disease. Clinicians are required to be more vigilant in evaluating patients with acquired reactive perforating collagenosis due to its unique association with malignancies and other systemic diseases.

Acquired reactive perforating collagenosis in association with prostate adenocarcinoma, chronic lymphocytic leukemia, and Graves' disease.

Acquired reactive perforating collagenosis is a rare skin disorder characterized by the presence of umbilicated pruritic papules and nodules. Transepidermal elimination of altered and perforating bundles of basophilic collagen from the epidermis is a characteristic histologic feature of acquired reactive perforating collagenosis. Along with its well-known association with systemic diseases such as diabetes mellitus, chronic renal failure, and dermatomyositis, there are reports of acquired reactive perforating collagenosis being associated with malignancies. Herein, we present a case of acquired reactive perforating collagenosis associated with chronic lymphocytic leukemia, prostate adenocarcinoma, and Graves's disease. Clinicians are required to be more vigilant in evaluating patients with acquired reactive perforating collagenosis due to its unique association with malignancies and other systemic diseases.

High-grade B-Cell lymphoma with MYC and BCL6 rearrangements associated with Richter transformation of chronic lymphocytic leukemia

Richter transformation (RT), or Richter syndrome, is defined as the transformation of chronic lymphocytic leukemia (CLL) to an aggressive B-cell lymphoma. The vast majority, up to 99%, transform into diffuse large B-cell lymphoma (DLBCL), with a small subset (<1%) becoming classical Hodgkin lymphoma. Approximately half of RT cases progress through a pathway involving dysregulation of C-MYC. High-grade B-cell lymphoma (HGBL) is a recent diagnostic category of aggressive B-cell lymphomas set forth in the updated 2017 WHO Classification of Hematopoietic and Lymphoid Tissues. HGBL with MYC and BCL2 and/or BCL6 rearrangements, formerly "double-hit" and "triple-hit" lymphomas, comprise the majority of HGBL cases. Patients with HGBL have a worse prognosis than those with diffuse large B-cell lymphoma. We present a case of RT with rearrangements of MYC and BCL6. To our knowledge, there are no reported cases of RT with a "double-hit" lymphoma genotype.

High-grade B-Cell lymphoma with MYC and BCL6 rearrangements associated with Richter transformation of chronic lymphocytic leukemia.

Richter transformation (RT), or Richter syndrome, is defined as the transformation of chronic lymphocytic leukemia (CLL) to an aggressive B-cell lymphoma. The vast majority, up to 99%, transform into diffuse large B-cell lymphoma (DLBCL), with a small subset (<1%) becoming classical Hodgkin lymphoma. Approximately half of RT cases progress through a pathway involving dysregulation of C-MYC. High-grade B-cell lymphoma (HGBL) is a recent diagnostic category of aggressive B-cell lymphomas set forth in the updated 2017 WHO Classification of Hematopoietic and Lymphoid Tissues. HGBL with MYC and BCL2 and/or BCL6 rearrangements, formerly "double-hit" and "triple-hit" lymphomas, comprise the majority of HGBL cases. Patients with HGBL have a worse prognosis than those with diffuse large B-cell lymphoma. We present a case of RT with rearrangements of MYC and BCL6. To our knowledge, there are no reported cases of RT with a "double-hit" lymphoma genotype.

Histoplasmosis diseminada como manifestación inicial del linfoma linfocítico de células pequeñas / Disseminated histoplasmosis as a first clinical manifestation in a patient with small lymphocytic lymphoma: A case report

RESUMEN El linfoma linfocítico de células pequeñas es una neoplasia de células B maduras con un amplio espectro de presentaciones clínicas. Las infecciones por gérmenes oportunistas no asociadas con el tratamiento, incluso en estadios avanzados de la enfermedad, tienen baja incidencia. Se han reportado muy pocos casos de pacientes con linfoma linfocítico de células pequeñas asociado a histoplasmosis diseminada que no habían recibido quimioterapia en el momento del diagnóstico. Se presenta el caso de una paciente de 82 años que fue hospitalizada por presentar tos seca intermitente, astenia y adinamia de un mes de evolución. Se le practicaron múltiples estudios para detectar infecciones o compromiso inmunológico o reumático, y se diagnosticó un síndrome adenopático extenso con compromiso cervical, torácico y retroperitoneal. En la citometría de flujo y en la biopsia de ganglio linfático cervical, se reportaron los fenotipos CD19+, CD20dim, CD5+, CD45+, CD23+, CD43neg y CD10neg, con restricción de la cadena ligera kappa, lo cual confirmó un linfoma linfocítico de células pequeñas. En la histopatología del ganglio, se observaron granulomas epitelioides sin necrosis, pero las coloraciones especiales no mostraron la presencia de microorganismos, en tanto que el cultivo del ganglio fue positivo para Histoplasma capsulatum. Se inició el tratamiento antifúngico con anfotericina B e itraconazol, y la paciente tuvo una adecuada evolución. Dado que no se cumplían los criterios para el tratamiento oncológico, se continuó con su observación mediante controles periódicos. Las infecciones oportunistas pueden ser la manifestación clínica inicial en pacientes con síndromes linfoproliferativos de bajo grado. Este caso demuestra que pueden desarrollarse, incluso, en ausencia de quimioterapia.

ABSTRACT The small lymphocytic lymphoma is a mature B cell neoplasm with a broad spectrum of clinical presentations. Opportunistic infections that are not related to the treatment, even in advanced stages, have a low incidence rate. There are few case reports in the medical literature of patients who have not received immunosuppressive therapy and present with small lymphocytic lymphoma associated with disseminated histoplasmosis at diagnosis. A female 82-year-old patient was admitted due to an intermittent dry cough, asthenia, and adynamia that had persisted for one month. Multiple studies to detect infections and immuno-rheumatic conditions were performed and an extensive cervical, thoracic and peritoneal adenopathic syndrome was diagnosed. A flow cytometry and a cervical lymph node biopsy were performed reporting CD19+, CD20dim, CD5+, CD45+, CD23+, CD43neg, and CD10neg phenotypes with restriction in the light kappa chain compatible with a small lymphocytic lymphoma. Epithelioid granulomas without necrosis were observed in the lymph node histopathology and special colorations showed no microorganisms. The culture from the lymph node was positive for Histoplasma capsulatum. We initiated treatment with amphotericin B and itraconazole with an adequate response. In the absence of compliance with oncology treatment criteria, the patient was managed on a "watch and wait" basis. Opportunistic infections could be the initial clinical manifestation in patients with low-grade lymphoproliferative syndromes. This case report shows that they can develop even in the absence of chemotherapy.

Cutaneous leukemic infiltration following varicella - a case of Wolf's isotopic response

Abstract Wolf's isotopic response designates the appearance of two subsequent unrelated dermatoses in the same anatomic location. We report the case of a 51-year-old man with a medical history of chronic lymphocytic leukemia without known extra-hematopoietic involvement. The patient developed a disseminated papulo-vesiculous eruption, diagnosed as varicella. Few days after recovering, an erythematous and violaceous papular dermatosis with histopathological examination compatible with leukemic infiltration appeared on the scars of previous herpetic lesions. Complete remission was obtained under systemic corticotherapy, without cutaneous recurrence or blastic transformation. Wolf's isotopic response is attributed to a localized immunologic imbalance following a certain stimulus. In this patient, herpetic infection acted as a local spur for inaugural cutaneous leukemic infiltration, with no impact on the prognosis for the underlying disease.

Mannose-binding lectin 2 (MBL2) gene polymorphisms do not influence frequency of infections in chronic lymphocytic leukemia patients.

BACKGROUND: Infectious complications represent the main cause of morbidity and mortality in chronic lymphocytic leukemia. It has been reported that polymorphisms of the mannosebinding lectin 2 (MBL2) genes are correlated with MBL protein serum levels and, consequently, are associated with the development of infectious diseases. OBJECTIVE: The purpose of this study was to investigate the possible association between MBL2 gene polymorphisms and risk of infection in chronic lymphocytic leukemia patients. METHODS: Peripheral blood samples from 116 chronic lymphocytic leukemia patients were collected; after genomic DNA extraction, real time polymerase chain reaction was used to determine the polymorphisms of the promoter region and exon 1 of the MBL2 gene. RESULTS: A high frequency of Binet stage A (p-value = 0.005) and absence of splenomegaly (p-value = 0.002) were observed in patients with no infection; however, variant alleles/ genotypes and haplotypes of this gene had no impact on the risk of infection. CONCLUSION: To the authors' knowledge, this is the first study describing the association between MBL2 polymorphisms and infectious disease in chronic lymphocytic leukemia. Although it was not possible to demonstrate any influence of MBL2 polymorphisms as a genetic modulator of infection in chronic lymphocytic leukemia, the authors believe that the present data are clinically relevant and provide the basis for future studies.

Involvement of memory T-cells in the pathophysiology of chronic lymphocytic leukemia.

The role of T-cells in the pathogenesis of chronic lymphocytic leukemia has recently gained much attention due to the importance of the constant interaction between neoplastic B-cells with microenvironment substratum and T-cells. It is believed that these interactions modulate the clinical course of the disease, mainly through the regulation of the expansion, differentiation, and survival of chronic lymphocytic leukemia B-cells. Importantly, this crosstalk may also change the number, function, and memory phenotype of normal T-cells, thereby altering the amplitude and/or efficiency of adaptive immunity in chronic lymphocytic leukemia patients. The present study presents an overview on important aspects of this immunological crosstalk, particularly on the abnormalities of chronic lymphocytic leukemia B-cells and the alterations in normal T-cells, with focus on the CD4 memory T-cell compartment that could offer survival signals to chronic lymphocytic leukemia B-cell clone(s) and contribute to the establishment and progression of the disease. The authors believe that understanding the biological consequences of the interaction between normal T- and neoplastic B-cells in chronic lymphocytic leukemia may allow for improvements in the prognostic information and therapeutic approaches for this disease.

Mannose-binding lectin 2 (MBL2) gene polymorphisms do not influence frequency of infections in chronic lymphocytic leukemia patients

Background: Infectious complications represent the main cause of morbidity and mortality in chronic lymphocytic leukemia. It has been reported that polymorphisms of the mannosebinding lectin 2 (MBL2) genes are correlated with MBL protein serum levels and, consequently, are associated with the development of infectious diseases. Objective: The purpose of this study was to investigate the possible association between MBL2 gene polymorphisms and risk of infection in chronic lymphocytic leukemia patients. Methods: Peripheral blood samples from 116 chronic lymphocytic leukemia patients were collected; after genomic DNA extraction, real time polymerase chain reaction was used to determine the polymorphisms of the promoter region and exon 1 of the MBL2 gene. Results: A high frequency of Binet stage A (p-value = 0.005) and absence of splenomegaly (p-value = 0.002) were observed in patients with no infection; however, variant alleles/ genotypes and haplotypes of this gene had no impact on the risk of infection. Conclusion: To the authors' knowledge, this is the first study describing the association between MBL2 polymorphisms and infectious disease in chronic lymphocytic leukemia. Although it was not possible to demonstrate any influence of MBL2 polymorphisms as a genetic modulator of infection in chronic lymphocytic leukemia, the authors believe that the present data are clinically relevant and provide the basis for future studies. .

Involvement of memory T-cells in the pathophysiology of chronic lymphocytic leukemia

The role of T-cells in the pathogenesis of chronic lymphocytic leukemia has recently gained much attention due to the importance of the constant interaction between neoplastic B-cells with microenvironment substratum and T-cells. It is believed that these interactions modulate the clinical course of the disease, mainly through the regulation of the expansion, differentiation, and survival of chronic lymphocytic leukemia B-cells. Importantly, this crosstalk may also change the number, function, and memory phenotype of normal T-cells, thereby altering the amplitude and/or efficiency of adaptive immunity in chronic lymphocytic leukemia patients. The present study presents an overview on important aspects of this immunological crosstalk, particularly on the abnormalities of chronic lymphocytic leukemia B-cells and the alterations in normal T-cells, with focus on the CD4 memory T-cell compartment that could offer survival signals to chronic lymphocytic leukemia B-cell clone(s) and contribute to the establishment and progression of the disease. The authors believe that understanding the biological consequences of the interaction between normal T- and neoplastic B-cells in chronic lymphocytic leukemia may allow for improvements in the prognostic information and therapeutic approaches for this disease.

Vasculite associada à ANCA e leucemia linfocítica crônica: uma rara associação / ANCA associated vasculitis and chronic lymphocytic leukemia: a rare association

O presente trabalho tem por objetivo uma discussão acerca do relato de um doente que teve o diagnóstico simultâneo de duas doenças pouco frequentes, a vasculite relacionada ao anticorpo anticitoplasma de neutrófilos e a leucemia linfocítica crônica. Ambas são doenças que podem apresentar envolvimento multissistêmico e, assim, causar confusão diagnóstica. Neste caso, o doente apresentou comprometimento renal, pulmonar, hematológico e ocular, que poderiam ser secundários tanto à vasculite quanto à leucemia. Com auxílio de exames de imagem, estudos anátomopatológicos, imuno-histoquímica e imunofenotipagem concluímos tratar-se de uma associação das duas doenças. Há, na literatura, outros relatos desta associação, no entanto, com pANCA positivo; este é o primeiro relato de leucemia linfocítica crônica associada à vasculite com cANCA positivo.

The aim of the present work is to discuss the report of a patient who had simultaneous diagnosis of two rare diseases, vasculitis related to antineutrophil cytoplasmic antibodies and chronic lymphocytic leukemia. Both are diseases that may be multisystemic and thus cause diagnostic confusion. In this case, the patient had renal, pulmonary, hematological, and ocular symptoms, which could be secondary to vasculitis both as to leukemia. With the aid of imaging studies, pathological studies, immunohistochemistry and immunophenotyping, we conclude that it was a combination of the two diseases. There are other reports in literature of this association, however, with pANCA positive, this is the first report of chronic lymphocytic leukemia associated with cANCA positive vasculitis.

Laboratory diagnosis of chronic myelomonocytic leukemia and progression to acute leukemia in association with chronic lymphocytic leukemia: morphological features and immunophenotypic profile.

Chronic myelomonocytic leukemia is a clonal stem cell disorder that is characterized mainly by absolute peripheral monocytosis. This disease can present myeloproliferative and myelodysplastic characteristics. According to the classification established by the World Health Organization, chronic myelomonocytic leukemia is inserted in a group of myeloproliferative/myelodysplastic disorders; its diagnosis requires the presence of persistent monocytosis and dysplasia involving one or more myeloid cell lineages. Furthermore, there should be an absence of the Philadelphia chromosome and the BCR/ABL fusion gene and less than 20% blasts in the blood or bone marrow. Phenotypically, the cells in chronic myelomonocytic leukemia can present myelomonocytic antigens, such as CD33 and CD13, overexpressions of CD56 and CD2 and variable expressions of HLA-DR, CD36, CD14, CD15, CD68 and CD64. The increase in the CD34 expression may be associated with a transformation into acute leukemia. Cytogenetic alterations are frequent in chronic myelomonocytic leukemia, and molecular mutations such as NRAS have been identified. The present article reports on a case of chronic myelomonocytic leukemia, diagnosed by morphologic and phenotypical findings that, despite having been suggestive of acute monocytic leukemia, were differentiated through a detailed analysis of cell morphology. Furthermore, typical cells of chronic lymphocytic leukemia were found, making this a rare finding.

Laboratory diagnosis of chronic myelomonocytic leukemia and progression to acute leukemia in association with chronic lymphocytic leukemia: morphological features and immunophenotypic profile

Chronic myelomonocytic leukemia is a clonal stem cell disorder that is characterized mainly by absolute peripheral monocytosis. This disease can present myeloproliferative and myelodysplastic characteristics. According to the classification established by the World Health Organization, chronic myelomonocytic leukemia is inserted in a group of myeloproliferative/myelodysplastic disorders; its diagnosis requires the presence of persistent monocytosis and dysplasia involving one or more myeloid cell lineages. Furthermore, there should be an absence of the Philadelphia chromosome and the BCR/ABL fusion gene and less than 20% blasts in the blood or bone marrow. Phenotypically, the cells in chronic myelomonocytic leukemia can present myelomonocytic antigens, such as CD33 and CD13, overexpressions of CD56 and CD2 and variable expressions of HLA-DR, CD36, CD14, CD15, CD68 and CD64. The increase in the CD34 expression may be associated with a transformation into acute leukemia. Cytogenetic alterations are frequent in chronic myelomonocytic leukemia, and molecular mutations such as NRAS have been identified. The present article reports on a case of chronic myelomonocytic leukemia, diagnosed by morphologic and phenotypical findings that, despite having been suggestive of acute monocytic leukemia, were differentiated through a detailed analysis of cell morphology. Furthermore, typical cells of chronic lymphocytic leukemia were found, making this a rare finding.

Monoclonal B-cell lymphocytosis: a brief review for general clinicians / Linfocitose monoclonal de células B: uma breve revisão para clínicos gerais

Monoclonal B-cell lymphocytosis (MBL) is a recently described medical condition that displays biological similarities to the most common subtype of adult leukemia in the Western world, i.e. chronic lymphocytic leukemia (CLL). Diagnostic criteria have been published with the aim of differentiating between these two entities. The overall prevalence of MBL is at least 100 times higher than that of CLL, which indirectly suggests that MBL is not necessarily a pre-leukemic condition, although in some circumstances, CLL cases can really be preceded by MBL. In view of this high prevalence rate, general clinicians and even non-hematological specialists have a high chance of being faced with individuals with MBL in their routine clinical practice. MBL is classified as "clinical MBL", "population-screening MBL" and "atypical MBL" and the clinical management of affected individuals depends greatly on this differentiation. The present review provides a guide to diagnosing and following up MBL patients.

A linfocitose monoclonal de células B (LMB) é uma condição médica recentemente descrita que exibe similaridades biológicas com o mais comum subtipo de leucemia em adultos de países ocidentais, qual seja, a leucemia linfocítica crônica (LLC). Critérios diagnósticos foram publicados com o intuito de separar as duas entidades. A prevalência global da LMB é pelo menos 100 vezes maior do que a da LLC, o que, indiretamente, sugere que a LMB não é necessariamente uma condição pré-leucêmica, embora, em algumas circunstâncias, casos de LLC possam realmente ser precedidos pela LMB. Em virtude dessa alta taxa de prevalência, clínicos gerais e mesmo outros especialistas não hematologistas têm grande chance de deparar-se com casos de LMB em suas rotinas clínicas. A LMB é classificada como "LMB clínica", "LMB de screening populacional" e "LMB atípica", sendo que o manuseio clínico dos indivíduos afetados depende substancialmente dessa diferenciação. A presente revisão fornece um guia para o diagnóstico e acompanhamento dos pacientes com LMB.