New developments in the diagnosis and characterization of Waldenström's macroglobulinemia.

INTRODUCTION: Waldenström's macroglobulinemia (WM) is defined as a lymphoplasmacytic lymphoma (LPL) with immunoglobulin M (IgM) monoclonal gammopathy and morphologic evidence of bone marrow infiltration by LPL. Immunophenotyping and genotyping provide a firm pathological basis for diagnosis and are particularly valuable in differential diagnosis between WM and related diseases. Emerging technologies in mutational analysis present new opportunities, but challenges remain around standardization of methodologies and reporting of mutational data across centers. AREAS COVERED: The review provides an overview of the diagnosis of WM, with a particular focus on the role of immunophenotyping and genotyping. EXPERT OPINION: Demonstration of LPL with a bone marrow biopsy is essential to reach a definitive diagnosis of WM. However, MYD88L265P and a typical WM immunophenotypic profile are valuable for the differential diagnosis of WM and related diseases, such as marginal zone lymphoma, multiple myeloma, and chronic lymphocytic leukemia. These methodologies must be utilized across centers and with appropriate standards followed in the evaluation and reporting of sensitivities and specificities. The diagnostic and/or prognostic value of mutations in genes such as CXCR4 and TP53 that are currently not routinely evaluated in the diagnosis of WM should be explored.

Acquired von willebrand syndrome secondary to monoclonal gammopathy of undetermined significance: long-term remission after treatment with bortezomib.

Monoclonal gammopathy of undetermined significance (MGUS) is a plasma cell disorder that can precede the diagnosis of multiple myeloma. MGUS is characterized by the presence of a monoclonal paraprotein without evidence of multiple myeloma or other lymphoplasmacytic malignancies. Even though MGUS is an asymptomatic condition that does not require management strategies other than periodic follow-up to prevent complications, secondary nonmalignant diseases may arise, requiring control of the plasma cell clone. Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder that occurs in patients with no prior personal or family history of bleeding. It is associated with several other disorders, such as neoplasia, mainly hematological (including MGUS and other lymphoproliferative disorders), autoimmune, infectious and cardiac diseases. At diagnosis, patients usually present with cutaneous and mucosal bleeding, including gastrointestinal bleeding. Here, we report a case of a patient with MGUS who developed AVWS after one year of follow-up. The patient was refractory to glucocorticoids and cyclophosphamide and achieved remission only after monoclonal paraprotein was eradicated following treatment with bortezomib and dexamethasone. Our report sdemonstrates that, for refractory cases, eradication of the monoclonal paraprotein may be necessary to treat bleeding complications due to MGUS-associated AVWS.

Biclonal Gammopathies in South Tunisia: Clinical and Biological Characteristics.

OBJECTIVE: Biclonal gammopathies (BGs) are rare situations characterized by the production of 2 monoclonal proteins. There are no available data on BGs in North Africa. We aimed to estimate the prevalence of BGs in our population and describe their clinical and laboratory features. METHODS: We conducted a 31-year retrospective study including patients with persistent double monoclonal bands based on the results of immunofixation/immunoelectrophoresis. RESULTS: A total of 35 patients with available clinical data (sex ratio, M/F = 1.53; mean age, 70 ±â€…10.87 years [range, 45-90 years]) were included. The main associated conditions were multiple myeloma (MM) (40%), BG of undetermined significance (BGUS) (34%), and lymphoproliferative diseases (23%). Only one-third of the patients had 2 monoclonal spikes on serum protein electrophoresis. The most common paraprotein combinations were immunoglobulin (Ig)G-IgG (25%) and IgG-IgA (23%) with different light chains in one-half of the cases. The mean follow-up was 25.6 months (median, 12 months). No BGUS evolved into a malignant disease. CONCLUSION: BGs are rare in clinical laboratory routine but must be accurately identified by the pathologist. Our cohort is characterized by a high prevalence of BGUS compared with MM.

Síndrome POEMS: desafios no diagnóstico de um caso atípico / POEMS syndrome: challenges in the diagnosis of an atypical case

Introdução: Síndrome POEMS trata de um raro evento paraneoplásico, sem relato atual na literatura sobre sua real prevalência. A maior parte dos casos ocorre em homens de meia idade. Relato do Caso:Paciente masculino, 65 anos, com queixa edema e parestesia em pernas que evoluiu para plegia, associada a hiporexia e fadiga. Investigação ambulatorial inicial evidenciou Polirradiculoneuropatia Inflamatória Desmielinizante Crônica (PIDC) de etiologia indefinida. Excluídos secundarismos, o paciente foi diagnosticado com hipotireoidismo primário, hipogonadismo severo, lesões hipercrômicas em pele, ascite, derrame pleural e trombocitose, além de gamopatia monoclonal IgA Lambda por imunofixação sérica. Sorologias virais negativas. Excluída a possibilidade de Mieloma Múltiplo e outras gamopatias, foi aventada a hipótese de Síndrome POEMS, sendo realizada dosagem de VEGF plasmática (425 pg/mL; VR = <96.2). Trata-se de um caso atípico na medida em que, lesões ósseas, presentes em até 97% dos casos, não foram evidenciadas no paciente em questão, tornando desafiador o diagnóstico. Conclusões: O diagnóstico de síndromes raras, embora desafiante, traz ao clínico um olhar mais amplo do paciente na medida em que incrementa o raciocínio clínico. [au]

Introduction: POEMS syndrome is a rare paraneoplastic event, with no current report in the literature about its real prevalence. Most cases occur in middle-aged men. Case Report: Male patient, 65 years old, complaining of edema and paresthesia in the legs that evolved to plegia, associated with hyporexia and fatigue. Initial outpatient investigation revealed Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) of undefined etiology. Excluding secondaries, the patient was diagnosed with primary hypothyroidism, severe hypogonadism, hyperchromic skin lesions, ascites, pleural effusion and thrombocytosis, in addition to monoclonal IgA Lambda gammopathy by serum immunofixation. Viral serologies was negative. Excluding the possibility of Multiple Myeloma and other gammopathies, the hypothesis of POEMS Syndrome was raised, and plasma VEGF measurement was performed (425 pg/mL; RV = <96.2). This is an atypical case in that bone lesions, present in up to 97% of cases, were not evidenced in the patient in question, making the diagnosis challenging. Conclusions: The diagnosis of rare syndromes, although challenging, brings the clinician a broader view of the patient as it increases clinical reasoning. [au]

Data on the clinical, analytical, and laboratory factors associated with negative anion gaps at an academic medical center.

The anion gap is a calculated parameter derived from the difference between the major plasma cations and anions in serum/plasma or whole blood, with a widely used simple equation utilizing concentrations of sodium, chloride, and bicarbonate. While there is extensive literature on the clinical significance and causes of elevated anion gaps, there is comparatively less data on low anion gaps. Occasionally, anion gap calculations result in a negative number (-1 or less). From the published literature, causes of these 'negative anion gaps' include laboratory error, specimen contamination or interference, hypoalbuminemia, extreme hyperkalemia, bromism, and paraproteins from multiple myeloma or similar pathologic processes. The data in this article present results from retrospective review of clinical chemistry and blood gas analysis testing at an academic medical center. The data include electrolyte concentrations and anion gap values derived from a total of 2,948,574 specimens (2,841,863 serum/plasma specimens analyzed on Roche Diagnostics clinical chemistry analyzers, 93,987 whole blood specimens analyzed on Radiometer blood gas analyzers, and 12,724 whole blood specimens on point-of-care chemistry devices) from 371,925 unique patients, clinical area where testing was ordered (for serum/plasma samples), sex, and age. For serum/plasma specimens with a negative anion gap, the data additionally include information from detailed chart review of possible factors and disease conditions contributing to the negative anion gap, pattern of electrolyte abnormalities, presence or absence of hypoalbuminemia, and corrected anion gap (if hypoalbuminemia is present).

POEMS (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal Protein, and Skin Changes): A Case Report of a Rare Paraneoplastic Syndrome.

POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes) syndrome is a multisystem disorder. Peripheral neuropathy and monoclonal plasma cell disorder are the most common manifestations of POEMS. Although osteosclerotic or mixed sclerotic-lytic lesions are typical, osteolytic lesions are rarely encountered. We present a case of a 39-year-old male with a history of multiple endocrine disorders who presented with paresthesia, edema, and hyperpigmentation and was eventually diagnosed with POEMS syndrome. Patients with unexplained neuropathy should be evaluated for POEMS syndrome, especially when it is associated with other findings like endocrinopathy, organomegaly, skin changes, or edema.

Morphometric Analysis of Lysosomes in the Renal Tubule in Monoclonal Gammopathy Using Transmission Electron Microscopy: "Mottled Appearance" and Beyond.

Lysosomal "mottled appearance", or uneven electron-dense content related to monoclonal gammopathy (MG), has been mainly described in light chain proximal tubulopathy (LCPT). We aimed to determine the ultrastructural characteristics of lysosomal mottled appearance in kidney biopsies and its association with LCPT and MG. Seventy-seven biopsies were grouped into LCPT (n = 5), MG conditions other than LCPT (n = 43), and non-MG conditions (n = 29). The mottled lysosomes in the renal tubules were evaluated using transmission electron microscopy and morphometric analysis. Mottled lysosomes were more prevalent (% of present cases) and frequent (no. of mottled lysosomes/20,000× ultramicroscopic field) in the LCPT group (100% and 8.20 ± 4.15/field) than in the MG (41.9% and 1.13 ± 2.05/field) and non-MG (37.9% and 0.80 ± 1.44/field) groups. In morphometric analysis of all mottled lysosomes (n = 520) detected from the 34 biopsies (5 LCPT, 18 MG, and 11 non-MG), we found that mottled lysosomes were larger, more irregular, and more electron-dense for the LCPT group than for the MG and non-MG groups. Therefore, mottled lysosomes can be present in disorders other than LCPT or even without MG. The morphological characteristics of mottled lysosomes could provide objective guidance for the diagnosis of LCPT.

Síndrome POEMS: desafios no diagnóstico de um caso atípico / POEMS syndrome: challenges in the diagnosis of an atypical case

Introdução: Síndrome POEMS trata de um raro evento paraneoplásico, sem relato atual na literatura sobre sua real prevalência. A maior parte dos casos ocorre em homens de meia idade; Relato do Caso: Relatamos o caso de um paciente masculino, 65 anos, admitido com queixa edema e parestesia em pernas que evoluiu para plegia, associada a hiporexia e fadiga. Investigação ambulatorial inicial evidenciou polirradiculoneuropatia inflamatória desmielinizante crônica (PIDC) de etiologia indefinida. Excluídos secundarismos para polirradiculoneuropatia inflamatória desmielinizante crônica, o paciente foi a seguir diagnosticado com hipotireoidismo primário, hipogonadismo severo, lesões hipercrômicas em pele, ascite, derrame pleural e trombocitose, além de gamopatia monoclonal IgA Lambda por imunofixação sérica. Sorologias para HIV, Sífilis e Hepatites todas negativas. Excluída a possibilidade de Mieloma Múltiplo e outras gamopatias, foi aventada a hipótese de Síndrome POEMS, sendo realizada dosagem de Fator de Crescimento Endotelial Vascular (VEGF) plasmática (425 pg/mL; VR = <96.2). O paciente passou então a preencher os critérios obrigatórios para diagnóstico, além de um maior (VEGF elevada) e vários outros menores. Trata-se de um caso atípico na medida em que, lesões ósseas, presentes em até 97% dos casos, não foram evidenciadas no paciente em questão, tornando desafiador o diagnóstico e sendo então necessário recorrer à dosagem de VEGF. O diagnóstico de síndromes raras, embora desafiante, traz ao clínico um olhar mais amplo do paciente na medida em que incrementa o raciocínio clínico. Difundir e explorar esse universo é cada vez mais necessário

Introduction: POEMS syndrome is a rare paraneoplastic event, with no current report in the literature about its real prevalence. Most cases occur in middle-aged men; Case Report: We report the case of a male patient, 65 years old, admitted with complaints of edema and paresthesia in the legs that progressed to plegia, associated with hyporexia and fatigue. Initial outpatient investigation revealed Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) of undefined etiology. Excluding secondaries for chronic inflammatory demyelinating polyradiculoneuropathy, the patient was subsequently diagnosed with primary hypothyroidism, severe hypogonadism, hyperchromic skin lesions, ascites, pleural effusion and thrombocytosis, in addition to monoclonal IgA Lambda gammopathy by serum immunofixation. All serologies for HIV, Hepatitis and syphilis were negative. Excluding the possibility of Multiple Myeloma and other gammopathies, the hypothesis of POEMS Syndrome was raised, and plasma Vascular Endotelial Growth Factor (VEGF) measurement was performed (425 pg/mL; RV = <96.2). The patient then started to fulfill the mandatory criteria for diagnosis, in addition to a major (elevated VEGF) and several other minors. This is an atypical case in that bone lesions, present in up to 97% of the cases, were not evidenced in the patient in question, making the diagnosis challenging and therefore requiring the use of VEGF dosage. The diagnosis of rare syndromes, although challenging, brings the clinician a broader view of the patient as it increases clinical reasoning. Spreading and exploring this universe is increasingly necessary

Macroglobulinemia de Waldenström: primer caso con confirmación molecular en Honduras / Waldenström Macroglobulinemia: first case with molecular confirmation in Honduras

Antecedentes: La Macroglobulinemia de Waldens- tröm (MW) es un desorden proliferativo en el cual está presente un Linfoma Linfoplasmocitoide (LLP) en la médula ósea y asociado a una gammapatía monoclonal IgM. Con una incidencia global de 3 casos por millón de personas-año, representa aproximadamente el 2% de todas las neoplasias hematológicas. Este es el primer caso documentado de MW en Honduras con confirmación molecular de la mutación MYD88 p.L265P. Descripción del caso: Paciente de 58 años de edad evaluado en 2017 con informe de biopsia que re - porta infiltración linfoplasmocitaria en glándula salival del labio infe- rior, refiriendo 3 meses de epistaxis y gingivorragia, anemia severa, leucopenia, episodios de lipotimia y pérdida de peso. Al examen físico presentó agrandamiento bilateral de glándula parótida y sub - mandibular, múltiples adenopatías cervicales, alteración en glándula tiroides, hepatomegalia leve y esplenomegalia masiva. Se encontra- ron valores elevados de TSH, microglobulina y LDH; eletroforesis y citometría de flujo de médula ósea sugestiva de desorden de IgM monoclonal. Se logró confirmación molecular mediante la detección de la mutación L265P en el gen MYD88. El paciente recibió esque- ma de primera línea con Ciclofosfamida, Adriamicina, Vincristina, Prednisona y Rituximab(CHOP-R), luego por recaída recibió mismo esquema por haber mostrado buena respuesta. Posteriormente, tras una nueva recaída recibió tratamiento con Chlorambucil pre - sentando nuevamente recaída. Se diagnosticó con MW refractaria y es candidato para recibir Ibrutinib; no disponible en nuestro me - dio. Conclusión: La escasa casuística de enfermedad de MW en Honduras dificulta el diagnóstico oportuno y tratamiento óptimo en nuestro medio...(AU)

Diagnostic challenges in systemic amyloidosis: a case report with clinical and laboratorial pitfalls.

Currently, there is growing evidence in the literature warning of misdiagnosis involving amyloidosis and chronic inflammatory demyelinating polyneuropathy (CIDP). Although inducing clinical manifestations outside the peripheral nervous system, light chain and transthyretin amyloidosis may initially present with peripheral neuropathy, which can be indistinguishable from CIDP, leading to a delay in the correct diagnosis. Besides, the precise identification of the amyloid subtype is often challenging. This case report exemplifies clinical and laboratory pitfalls in diagnosing amyloidosis and subtyping amyloid, exposing the patient to potentially harmful procedures.

A rare case of IgE kappa monoclonal gammopathy of undetermined significance identified in a Swedish female.

Monoclonal gammopathies involving immunoglobulin E (IgE) is a very rare phenomenon, with less than 70 cases being previously described in the literature. The IgE monoclonal gammopathies include malignant plasma cell disorders such as IgE multiple myeloma (MM), as well as the associated premalignant condition IgE monoclonal gammopathy of undetermined significance (MGUS). We report a case of a 41-year-old woman presenting with an IgE kappa monoclonal protein following routine laboratory testing. Serum protein electrophoresis (SPEP) initially showed a monoclonal protein in the beta-2 fraction, at an estimated concentration of <4 g/L. Subsequent serum immunofixation electrophoresis (SIFE) including antisera to Ig heavy chains delta and epsilon confirmed the presence of an IgE kappa monoclonal protein. Analysis of serum free light chains (FLCs) showed increased levels of kappa FLC, resulting in an abnormally elevated kappa/lambda FLC ratio. No Bence-Jones proteinuria was present. Bone marrow aspiration showed 6% plasma cells, and no sign of myeloma-associated end-organ damage was evident. Consequently, the patient was diagnosed with IgE kappa MGUS. In the present report, the clinical characteristics of the patient are compared to previous descriptions of IgE monoclonal gammopathy. The report further emphasizes the importance of considering the presence of monoclonal IgD or IgE when SIFE shows a clear band positive for a light chain but is negative for Ig heavy chains gamma, alpha and mu.

Patologías cutáneas asociadas a gammapatías monoclonales: ¿qué sabemos hasta ahora? / Dermatological manifestations of monoclonal gammopathies

Monoclonal gammopathies of uncertain significance (MGUS) correspond to pre-malignant hematological disorders characterized by the production of a monoclonal protein and infiltration of less than 10% of the bone marrow by plasma cells. Its importance lies in the risk of progression to malignant disorders and in the association with different renal, neurological and skin manifestations. There are pathophysiological mechanisms that support a causal relationship between monoclonal gammopathies (MGs) and different skin diseases, such as type I cryoglobulinemia (CG), primary systemic amyloidosis (PSA) or necrobiotic xanthogranuloma (NXG). However, there is a group of skin diseases associated with MGs whose pathogenesis has not been elucidated. In this context, the role of the dermatologist is crucial in the suspicion of different haematological disorders based on skin manifestations and in the multidisciplinary treatment of these patients. In this article, we carry out an exhaustive review of the literature published in this area and propose a screening algorithm for MGs in patients with specific skin diseases.

Diagnostic challenges in systemic amyloidosis: a case report with clinical and laboratorial pitfalls

Currently, there is growing evidence in the literature warning of misdiagnosis involving amyloidosis and chronic inflammatory demyelinating polyneuropathy (CIDP). Although inducing clinical manifestations outside the peripheral nervous system, light chain and transthyretin amyloidosis may initially present with peripheral neuropathy, which can be indistinguishable from CIDP, leading to a delay in the correct diagnosis. Besides, the precise identification of the amyloid subtype is often challenging. This case report exemplifies clinical and laboratory pitfalls in diagnosing amyloidosis and subtyping amyloid, exposing the patient to potentially harmful procedures.

Síndrome de hiperviscosidade em paciente com mieloma múltiplo / Hyperviscosity syndrome in multiple myeloma patients

O mieloma múltiplo é uma neoplasia progressiva e incurável de células B, caracterizado pela proliferação desregulada e clonal de plasmócitos na medula óssea. A síndrome de hiperviscosidade é uma das complicações relacionadas às gamopatias monoclonais, sendo considerada emergência oncológica. O objetivo deste estudo foi descrever o quadro clínico de um paciente diagnosticado com mieloma múltiplo que apresentou síndrome de hiperviscosidade, avaliando a prevalência de sinais e sintomas, bem como características fisiopatológicas dessa entidade clínica. Foi revisado o prontuário de um paciente internado na enfermaria da Clínica Médica do Hospital Regional do Cariri (CE) no período de junho a julho de 2018. Além disso, foi realizada revisão de literatura em base de dados (PubMed®) direcionada ao tema proposto. O diagnóstico de mieloma múltiplo foi comprovado por mielograma, sendo prontamente iniciada a corticoterapia e avaliada a resposta clínica após essa terapêutica. Apesar de incomum e menos frequentemente relacionada ao mieloma múltiplo, a síndrome de hiperviscosidade está relacionada a uma grande taxa de mortalidade quando apresenta diagnóstico tardio. A terapia de primeira linha indicada para a síndrome de hiperviscosidade foi a plasmaferese, no entanto, as condições clínicas (instabilidade hemodinâmica) impossibilitaram sua realização. O desfecho deste caso foi o óbito do paciente. Concluiu-se que o diagnóstico precoce e a intervenção terapêutica estão diretamente relacionados à ocorrência de menor incidência de complicações relacionadas ao mieloma múltiplo e à síndrome de hiperviscosidade.

Multiple myeloma is a progressive and incurable B-cell neoplasm characterized by unregulated and clonal proliferation of plasmocytes in the bone marrow. Hyperviscosity syndrome is one of the complications related to monoclonal gammopathies and is considered an oncological emergency. The aim of this study was to describe the clinical condition of a patient diagnosed with multiple myeloma who presented hyperviscosity syndrome, evaluating the prevalence of symptoms and signs, as well as the pathophysiological characteristics of this clinical entity. The medical records of a patient admitted to the Internal Medicine ward of the Hospital Regional do Cariri (CE) from June to July of 2018 were reviewed. In addition, we conducted a literature review in a database (PubMed®) directed to the theme proposed. The diagnosis of multiple myeloma was confirmed by myelogram, and corticosteroid therapy was promptly initiated and the clinical response was evaluated after this therapy. Although uncommon and less frequently related to multiple myeoloma, hyperviscosity syndrome is related to a high mortality rate when diagnosed late. The first line therapy indicated to hyperviscosity syndrome was plasmapheresis; however, the clinical conditions (hemodynamic instability) precluded its performance. The outcome of this case was the patient's death. Thus, it was concluded that early diagnosis and therapeutic intervention are directly related to the occurrence of lower incidence of complications related to multiple myeloma and hyperviscosity syndrome.

Nefropatías secundarias a paraproteína: perfil clínico a partir de hallazgos histológicos

Background: One of the devastating consequences of monoclonal gammopathies is the development of end-stage kidney disease, which can be prevented with an early diagnosis. Renal involvement can be secondary to saturation of paraproteins with intratubular precipitation or the glomerular deposition of paraproteins with secondary inflammation and destruction. These conditions can also be associated with monoclonal gammopathies that do not meet hematological treatment criteria, called monoclonal gammopathies of renal significance (MGRS). Aim: To report a retrospective analysis of patients who underwent a renal biopsy and whose final diagnosis was a form of monoclonal gammopathy. Material and Methods: We reviewed the clinical and laboratory features and response to treatment of 22 patients aged 63 ± 12 years (55% women) with a pathological diagnosis of a nephropathy associated with paraproteinemia. Results: The most common hematological diagnosis was amyloidosis in 50% of patients, followed by cast nephropathy. The predominant clinical presentations were proteinuria (without nephrotic syndrome) and nephritic syndrome. Classic criteria such as erythrocyte sedimentation rate > 100 mm/h and protein-albumin gap were unusual. Serum light chain quantification was the test with the best yield to detect paraproteins. Conclusions: In this group of patients, light chains tend to affect the kidney more commonly than heavy chains. The prognosis of multiple myeloma is much worse than MGRS.

Necrobiotic Xanthogranuloma Coexists with Diffuse Normolipidemic Plane Xanthoma and Multiple Myeloma.

Necrobiotic xanthogranuloma (NXG), is a rare multisystem disease that manifests as cutaneous inflammatory lesions, and is commonly associated with lymphoproliferative disease. Diffuse normolipemic plane xanthoma (NX), is also a rare, acquired disease that is often associated with systemic diseases such as lymphoproliferative disease. Both of these diseases have been reported to be associated with monoclonal gammopathy (MG). However, there are few cases in which these diseases co-exist. A 78-year-old female, who had a known case of NX on the neck and axillary area, presented with an asymptomatic erythematous plaque on her left supraclavicular area. Histopathological examination showed lymphoid aggregates, necrobiotic areas, and granulomatous inflammation in the dermis. Numerous foreignbody and Touton type giant cells were noticed. Serum protein immunoelectrophoresis showed an IgG kappa type MG. Lipid profile of the patient was normal. Bone marrow examination showed plasma cell myeloma. Based on these histologic and laboratory results, we diagnosed this lesion as NXG coexisting with NX and multiple myeloma. She was started on treatment with bortezomib and melphalan for multiple myeloma, and high-dose systemic corticosteroid and triamcinolone intralesional injection for the skin lesion. After 3 months of treatment, the NXG skin lesion and MG improved.

Necrobiotic Xanthogranuloma Coexists with Diffuse Normolipidemic Plane Xanthoma and Multiple Myeloma

Fibrillary Glomerulonephritis: Clinicopathologic Features and Atypical Cases from a Multi-Institutional Cohort.

BACKGROUND AND OBJECTIVES: Fibrillary GN has been defined as an immune complex-mediated GN with amyloid-like fibrils larger than amyloid which are IgG positive and Congo red negative. With discovery of DNAJB9 as a highly sensitive and specific marker for fibrillary GN, the specificity of the morphologic criteria for establishing the diagnosis of fibrillary GN has come into question. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We sought to (1) determine anatomic characteristics that best define fibrillary GN and (2) identify clinical and pathologic features that predict outcomes. RESULTS: We retrospectively reviewed kidney biopsies from patients diagnosed with fibrillary GN or suspected fibrillary GN between 1997 and 2017 (n=266, 65% female, median age 61). Approximately 11% of kidney biopsies had one or more unusual feature including monotypic deposits, Congo red positivity, or unusual fibril diameter. Fibrillary GN as a possible monoclonal gammopathy of renal significance represented <1% of cases. Immunostaining for DNAJB9 confirmed fibrillary GN in 100% of cases diagnosed as fibrillary GN and 79% of atypical cases diagnosed as possible fibrillary GN. At a median time of 24 months (interquartile range, 8-46 months) after biopsy (n=100), 53% of patients reached the combined primary outcome of ESKD or death, 18% had CKD, and 18% had partial remission. On multivariable analysis, male sex (adjusted hazard ratio [aHR], 3.82; 95% confidence interval [95% CI], 1.97 to 7.37) and eGFR were the most significant predictors of primary outcome (aHR of 8.02 if eGFR <30 ml/min per 1.73 m2 [95% CI, 1.85 to 34.75]; aHR of 6.44 if eGFR 30 to <45 ml/min per 1.73 m2 [95% CI, 1.38 to 29.99]). Immunosuppressive therapy with rituximab was significantly associated with stabilization of disease progression. CONCLUSIONS: Detection of DNAJB9 is a useful diagnostic tool for diagnosing atypical forms of fibrillary GN. The outcomes for fibrillary GN are poor and progression to ESKD is influenced predominantly by the degree of kidney insufficiency at the time of diagnosis and male sex. Rituximab may help preserve kidney function for select patients with fibrillary GN. PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_11_04_CJN03870319.mp3.