Maladie de dépôts d’immunoglobulines monoclonales de type Randall : du diagnostic au traitement

Randall-Type Monoclonal Immunoglobulin Deposition Disease in Bone Scintigraphy

ABSTRACT

Bone scintigraphy is recognized as a noninvasive alternative to endomyocardial biopsy for the diagnostic of wild-type (wATTR) and hereditary ATTR amyloidosis (hATTR). Light chain amyloidosis (AL), Randall-type monoclonal immunoglobulin deposition disease , sarcoidosis, hemochromatosis, Fabry disease, and mucopolysaccharidoses are differential diagnosis of ATTR amyloidosis. Bone scintigraphy allows visualization of extracardiac involvements of AL amyloidosis: pleural, retroperitoneal, liver, spleen, and soft tissue. We report the case of a patient who underwent bone scintigraphy for suspected ATTR amyloidosis. Bone scan showed cardiac (Perugini score 2), hepatic, and renal hyperfixation. A cardiac biopsy demonstrated a Randall-type deposit, without amyloid deposit.

[Nephropathy associated with monoclonal immunoglobulins: From clonal expansion B to renal toxicity of pathological immunoglobulins]

Germinal center regulation pathways are often involved in lymphomagenesis and myelomagenesis. Most of the lymphomas (and multiple myeloma) derive from post-germinal center B-cells that have undergone somatic hypermutation and class switch recombination. Hence, B-cell clonal expansion can be responsible for the presence of a monoclonal component (immunoglobulin) of variable titer which, owing to physicochemical properties, can provoke pathologically defined entities of diseases. These diseases can affect any functional part of the kidney, by multiple mechanisms, either well known or not. The presence of renal deposition is influenced by germinal gene involved, immunoglobulin primary structure, post-translational modifications and microenvironmental interactions. The two ways immunoglobulin can cause kidney toxicity are (i) an excess of production (overcoming catabolism power by proximal tubule epithelial cells) with an excess of free light chains within the distal tubules and a subsequent risk of precipitation due to local physicochemical properties; (ii) by structural characteristics that predispose immunoglobulin to a renal disease (whatever their titer). The purpose of this manuscript is to review literature concerning the pathophysiology of renal toxicities of clonal immunoglobulin, from molecular B-cell expansion mechanisms to immunoglobulin renal toxicity.

Bortezomib-Based Chemotherapy with Autologous Stem Cell Transplantation for Monoclonal Gammopathy of Renal Significance: A Case Report and Literature Review

BACKGROUND/AIMS

The term monoclonal gammopathy of renal significance (MGRS) was introduced in 2012 to emphasize kidney lesions in monoclonal gammopathy patients. Bortezomib-based chemotherapy has become the first-line treatment for MGRS.

OBJECTIVES

The objective of this study was to investigate whether the strategy of combining chemotherapy with autologous stem cell transplantation (ASCT) could improve prognosis and decrease functional kidney impairment in patients with MGRS.

METHODS

We reported the case of a 44-year-old Asian patient who was diagnosed with MGRS and received 5 cycles of Velcade® (a trade name for bortezomib), thalidomide, and dexamethasone therapy (VTD therapy), and subsequently underwent ASCT. In addition, we performed a literature review and summarized the latest advances in the characterization, treatment, and prognosis of MGRS.

RESULTS

The patient was diagnosed with light chain deposition disease by renal biopsy. After 5 cycles of VTD therapy, the patient had a very good partial response characterized by the resolution of M-protein (20.2% before treatment vs. 2.5% after treatment), remission of the level of serum free lambda (FLAM; over 80% decline), and normalization of the serum free light chain (sFLC) ratio (κ to λ). He also had a renal response characterized by a decreased serum creatinine level (1.61 vs.1.34 mg/dL) and less severe proteinuria (6.77 g/24 h vs.1.264 g/24 h) after chemotherapy. Importantly, after ASCT, the patient achieved a complete response (CR) characterized by a negative serum immunofixation electrophoresis (IFE) result and a dramatic decrement in FLAM (over 90%). Furthermore, 6 months after ASCT, the patient still remained in stable condition with a negative IFE result, normal sFLC ratio, and low level of serum creatinine (1.31 mg/dL) and proteinuria (0.339 g/24 h). In our retrospective literature analysis, we found that MGRS patient survival time and renal outcome had been markedly improved by current therapies due to the popularization of bortezomib-based chemotherapy and ASCT.

CONCLUSIONS

The patient successfully achieved CR after VTD therapy followed by ASCT. However, this treatment is controversial, and a standard therapy recommendation for MGRS has not been established. Bortezomib-based chemotherapy combined with ASCT may have prospects for the treatment of MGRS, but the exact effects of ASCT remain unclear and should be thoroughly investigated.

Monoclonal gammopathy of renal significance: clinical manifestation, pathogenic characteristic and treatment

Monoclonal gammopathy of renal significance (MGRS) is a group of renal disorders caused by a monoclonal immunoglobulin (MIg) secreted by a dangerous plasmatic/B-cell clone hyperplasia through MIg deposition or dysfunction of complement pathway, with increasing risk of progress to end stage renal disease (ESRD) and the underlying hematologic malignancy. The combination of renal biopsy, complete laboratory examination and bone marrow biopsy is an indispensable diagnostic tool for MGRS to identify accurately and unequivocally the pathogenic monoclonal MIg and provide guidance to treatment. Treatment of MGRS is composed of conventional therapy, chemotherapy, and stem cell transplantation to target the underlying clone and eliminate the noxious MIg on the basis of clinical data of some retrospective studies and a small amount of prospective trial. In addition, it is worthwhile point out assessment of therapeutic effect is significantly relevant for renal and overall prognosis. Thus, by comprehensively analyzing the clinical manifestations and pathogenic characteristic of MGRS, early recognition and prompt treatment can improve the prognosis and prevent post-translation recurrence with multidisciplinary cooperation.

Paraprotein deposits in the skin

Cutaneous manifestations secondary to paraprotein deposits in the skin include a group of different disorders that although rare, may be the first clinical manifestation of the underlying hematologic dyscrasia. In this article we review the clinical manifestations and histopathologic findings of the processes that result from specific deposition of the paraprotein in different structures of the skin. Paraneoplastic processes frequently associated with hematologic malignancies will not be covered in this review. Some of the disorders included here result from deposition of the intact paraprotein in the skin, whereas in other cases the lesions are due to deposition of modified paraproteins in the form of amyloid substance, cryoglobulins, or crystalglobulins. Cutaneous amyloidoma refers to nodular dermal deposits of amyloid derived from immunoglobulin light chains produced by local plasma cells in the absence of systemic amyloidosis. Dermatologists and dermatopathologists should be aware of the clinical and histopathologic features of these rare disorders because sometimes the cutaneous lesions are the first sign of an underlying silent hematologic malignancy with paraproteinemia.

Long-term renal survival of γ3-heavy chain deposition disease: a case report

Background

Monoclonal immunoglobulin deposition disease (MIDD) is characterized by the non-amyloid deposition of monoclonal immunoglobulin fragments in the basement membranes. Heavy chain deposition disease (HCDD) is a type of MIDD. HCDD is an extremely rare disease, and only three cases have been reported in Japan up to the present. The prognosis of HCDD is very poor, and optimal treatment has not been established. Only a few cases of HCDD with favorable long-term renal prognosis have been reported to date.

Case presentation

The authors describe a 61-year-old woman who presented with massive proteinuria, progressive kidney impairment, and hypocomplementemia. Kidney biopsy was performed for a precise diagnosis. On light microscopy, glomerules were lobulated and presented with nodular sclerosing glomerulopathy with membranoproliferative glomerulonephritis-like features. Immunofluorescence studies were positive for IgG, C3, and C1q within the mesangial nodules and in a linear distribution along the capillary walls without associated deposition of light chains. Staining for IgG showed the presence of linear deposits along tubular basement membranes. The analysis of the IgG subclass stain demonstrated intense positivity for IgG3 only. Electron microscopy revealed non-organized electron-dense deposits in the expanded mesangial area and inner aspect of the glomerular basement membranes. In accordance with the histological findings, we diagnosed γ3-HCDD. There was no evidence of plasma cell dyscrasia as a result of bone marrow aspiration. Serum and urine monoclonal proteins were not detected by immunoelectrophoresis and immunofixation electrophoresis. The serum free light chain ratio was within normal range. At first, prednisolone was administrated at a dose of 40 mg/day. However, a therapeutic effect was not observed. Urinary protein was not decreased and renal function further deteriorated. Therefore, melphalan plus prednisolone (MP) therapy was initiated. After 4 courses of MP therapy, the clinical parameters, including proteinuria, serum creatinine, albumin, and complement level (C3 and C4) were ameliorated. To date, the patient has been followed for 28 months, and long-term renal survival has been observed.

Conclusions

In this case, hematologic disease such as multiple myeloma was not detected; however, MP therapy was effective. Recently, the novel concept of monoclonal gammopathy of renal significance (MGRS) has been reported. MIDD, which includes HCDD, is one category of MGRS. In MGRS, aggressive chemotherapy may induce favorable renal outcomes.

[Classification and therapeutic management of monoclonal gammopathies of renal significance]

Two categories of renal disorders associated with monoclonal gammopathies are to be distinguished, according to the characteristics of the underlying B-cell clone. The first group of renal diseases always occurs in the setting of high tumor mass with production of large amounts of monoclonal immunoglobulins. The main complication is the so-called myeloma cast nephropathy, which almost invariably complicates high tumor mass myeloma. The second group includes all renal disorders caused by a monoclonal immunoglobulin secreted by a nonmalignant B-cell clone, and currently referred as a "monoclonal gammopathy of renal significance (MGRS)". This term was introduced to distinguish monoclonal gammopathies that are responsible for the development of kidney damage from those that are truly benign. The spectrum of renal diseases in MGRS is wide and its classification relies on the localization of renal lesions, either glomerular or tubular, and on the pattern of ultrastructural organization of immunoglobulin deposits. Physicochemical characteristics of the pathogenic monoclonal immunoglobulin are probably involved in their propensity to deposit or precipitate in the kidney, as illustrated by the high rate of recurrence of each specific type after kidney transplantation. Early diagnosis and efficient chemotherapy targeting the causal B-cell clone are mandatory to improve renal prognosis and patient survival.