Multiple myeloma complicated with light chain cast nephropathy with focal amyloidosis: A case report

This case report describes a rare and interesting case of a patient with multiple myeloma complicated with light chain (LC) cast nephropathy and focal amyloidosis. The patient presented with acute kidney injury, anaemia and bone lesions. The diagnosis was confirmed by bone marrow biopsy, serum and urine electrophoresis and kidney biopsy. The patient was treated with isazomil, pomalidomide and dexamethasone combination chemotherapy, followed by autologous stem cell transplantation. The patient achieved clinical remission, stable renal function and improved serum lambda free LC levels. This case highlights the challenges and advances in the diagnosis and treatment of this condition.

Clinicopathological Profile of Paraprotein-Associated Kidney Disease in Monoclonal Gammopathies: An Observational Study

Background Renal involvement in monoclonal gammopathies presents with different clinico-morphological patterns and can manifest at the onset or the late phase of hematological disease, or after chemotherapy. The spectrum is ever-expanding with advancements in diagnostic methods. Renal biopsy is needed for accurate diagnosis, as each of these patterns carries therapeutic and prognostic implications. Methods A total of 41 cases of monoclonal gammopathies were included in the study. Clinical, biochemical, and hematological details were obtained, and pathological variables were observed. Patients were followed till the maximum possible period, and treatment history and follow-up creatinine details were collected. Results The spectrum of renal biopsy lesions observed included light chain cast nephropathy (LCCN) n=19, amyloidosis n=11, monoclonal immunoglobulin deposition disease (MIDD) n=6, and proliferative glomerulonephritis with monoclonal immunoglobulin deposition (PGNMID) n=5; 10 of these cases can be categorized as monoclonal gammopathy of renal significance (MGRS). Acute kidney injury (AKI) (41%) is the predominant clinical presentation in general whereas the majority of amyloidosis cases presented with nephrotic and sub-nephrotic proteinuria. LCCN cases had high serum creatinine and calcium, positivity for M-spike, as well as a high FLC ratio, compared to the other types. Around 100% of LCCN and MIDD patients had myeloma and 100% of PGNMID cases had normal marrow. Conclusion More than three-fourths of patients were diagnosed with monoclonal gammopathies with biochemical and hematological workups after an initial kidney biopsy. The clinicopathological profile of these patients had a broad spectrum but there were still some consistent findings within the different types. A subgroup of patients (MGRS) had undetectable serum paraproteins but had monoclonal immunoglobulin deposition in the kidney.

Clinic-pathological characteristics of rare tubulointerstitial diseases

OBJECTIVES

Tubulointerstitial diseases is one of the common causes of renal dysfunction. Some rare pathological types are easy to be misdiagnosed and missedly diagnosed because of their low prevalence and relatively insufficient understanding, which affects the treatment and prognosis of patients. This study aims to explore clinical manifestations and pathological characteristics of several rare tubulointerstitial diseases, and therefore to improve their diagnosis and treatment.

METHODS

A total of 9 363 patients diagnosed by renal biopsy in the Department of Nephrology, Second Xiangya Hospital, Central South University from November 2011 to September 2021 were selected. Six cases of light chain cast nephropathy (LCCN), 2 cases of light chain proximal tubulopathy (LCPT), 1 case of LCCN with LCPT, 4 cases of genetic tubulointerstitial disease, and 6 cases of non-genetic related tubulointerstitial lesion were screened out, and their clinical manifestations and renal biopsy pathological results were collected, compared, and analyzed.

RESULTS

Patients with LCCN presented with mild to moderate anemia, microscopic hematuria, and mild to moderate proteinuria. Compared with patients with LCPT, proteinuria and anemia were more prominent in patients with LCCN. Five patients with LCCN and 2 patients with LCPT had elevated serum free kappa light chain. Five patients with LCCN presented clinically with acute kidney injury (AKI). Two patients with LCPT and 1 patient with LCCN and LCPT showed CKD combined with AKI, and 1 LCPT patient presented with typical Fanconi syndrome (FS). Five patients with LCCN, 2 patients with LCPT, and 1 patient with LCCN and LCPT were diagnosed with multiple myeloma. Five patients with LCCN had kappa light chain restriction in tubules on immunofluorescence and a "fractured" protein casts with pale periodic acid-Schiff (PAS) staining on light microscopy. Immunohistochemical staining of 2 LCPT patients showed strongly positive kappa light chain staining in the proximal tubular epithelial cells. And monoclonal light chain crystals in crystalline LCPT and abnormal lysosomes and different morphological inclusion bodies in noncrystalline LCPT were observed under the electron microscope. Six patients with LCCN were mainly treated by chemotherapy. Renal function was deteriorated in 1 patient, was stable in 4 patients, and was improved in 1 patient. Two patients with LCPT improved their renal function after chemotherapy. Four patients with genetic tubulointerstitial disease were clinically presented as CKD, mostly mild proteinuria, with or without microscopic hematuria, and also presented with hyperuricemia, urine glucose under normal blood glucose, anemia, polycystic kidneys. Only 1 case had a clear family history, and the diagnosis was mainly based on renal pathological characteristics and genetic testing. Compared with patients with non-genetic related tubulointerstitial lesion, patients with genetic tubulointerstitial disease had an earlier age of onset, higher blood uric acid, lower Hb and estiated glomemlar fitration (eGFR), and less edema and hypertension. Renal pathology of genetic tubulointerstitial disease presented tubular atrophy and interstitial fibrosis, abnormal tubular dilation, glomerular capsuledilation, and glomerular capillary loop shrinkage. Glomerular dysplasia and varying degrees of glomerular sclerosis were observed. Genetic tubulointerstitial disease patients were mainly treated with enteral dialysis, hypouricemic and hypoglycemic treatment. Two genetic tubulointerstitial disease patients had significantly deteriorated renal function, and 2 patients had stable renal function.

CONCLUSIONS

Patients with AKI or FS, who present serum immunofixation electrophoresis and/or serum free kappa light chain abnormalities, should be alert to LCCN or LCPT. Renal biopsy is a critical detection for diagnosis of LCCN and LCPT. Chemotherapy and stem cell transplantation could delay progression of renal function in patients with LCCN and LCPT. If the non-atrophic area of the renal interstitium presents glomerular capsule dilatation, glomerular capillary loop shrinkage, and abnormal tubular dilatation under the light microscopy, genetic tubulointerstitial disease might be considered, which should be traced to family history and can be diagnosed by genetic testing.

The characteristics of patients with kidney light chain deposition disease concurrent with light chain amyloidosis

The type of monoclonal light chain nephropathy is thought to be largely a function of the structural and physiochemical properties of light chains; hence most affected patients have only one light chain kidney disease type. Here, we report the first series of kidney light chain deposition disease (LCDD) concomitant with light chain amyloidosis (LCDD+AL), with or without light chain cast nephropathy (LCCN). Our LCDD+AL cohort consisted of 37 patients (54% females, median age 70 years (range 40-86)). All cases showed Congo red-positive amyloid deposits staining for one light chain isotype on immunofluorescence (62% lambda), and LCDD with diffuse linear staining of glomerular and tubular basement membranes for one light chain isotype (97% same isotype as the amyloidogenic light chain) and ultrastructural non-fibrillar punctate deposits. Twelve of 37 cases (about 1/3 of patients) had concomitant LCCN of same light chain isotype. Proteomic analysis of amyloid and/or LCDD deposits in eight revealed a single light chain variable domain mutable subgroup in all cases (including three with separate microdissections of LCDD and amyloid light chain deposits). Clinical data on 21 patients showed proteinuria (100%), hematuria (75%), kidney insufficiency and nephrotic syndrome (55%). Extra-kidney involvement was present in 43% of the patients. Multiple myeloma occurred in 68% (about 2/3) of these patients; none had lymphoma. On follow up (median 16 months), 63% developed kidney failure and 56% died. The median kidney and patient survivals were 12 and 32 months, respectively. LCDD+AL mainly affected patients 60 years of age or older. Thus, LCDD+AL could be caused by two pathological light chains produced by subclones stemming from one immunoglobulin light chain lambda or kappa rearrangement, with a distinct mutated complementary determining region.

Light chain cast nephropathy caused by plasmablastic lymphoma of the bladder

Introduction: Plasmablastic lymphoma (PBL) is a rare form of B-cell lymphoma typically seen in patients with underlying immunosuppression such as HIV, autoimmune disease, and organ transplantation. PBL in HIV-positive patients usually originates from the gastrointestinal tract, with a predilection for the oral cavity. Bladder involvement by PBL is exceedingly rare, and cast nephropathy due to κ light chain-secreting PBL has not been reported previously. Case report: We report a patient who presented with acute kidney injury (AKI) in the setting of HIV, and was found to have a bladder tumor. Bladder pathology revealed a high-grade PBL with κ light chain restriction. Renal biopsy showed κ light chain cast nephropathy, presumably secondary to κ light chain-secreting PBL. Conclusion: Although the prognosis of PBL is poor, our patient recovered from AKI, achieved complete hematologic remission with chemotherapy, and underwent successful autologous stem cell transplant.

Monoclonal Gammopathy of Renal Significance Triggered by Viral E Hepatitis

Monoclonal gammopathy of undetermined significance does not have end organ damage, but a proportion of cases manifest with renal injury when it is called monoclonal gammopathy of renal significance (MGRS). Herein, we describe a case of acute hepatitis E infection, which precipitated the development of MGRS. The patient underwent kidney biopsy for elevated creatinine with clinical suspicion of drug-induced interstitial nephritis. On light microscopy, there were periodic acid–Schiff negative-fractured casts in tubules with giant cell reaction around them. The tubular epithelial cells showed intracytoplasmic bile pigment. On direct immunofluorescence, casts showed kappa restriction. A diagnosis of bilirubin proximal tubulopathy and light chain cast nephropathy was made, and possibility of myeloma was suggested. On further evaluation, κ:λ ratio was 27, β2 microglobulin was 8036 ng/ml, and bone marrow examination showed 5% plasma cells. There were no bony lesions, and serum calcium was 8.6 mg/dl. The present case is unique in two aspects. First, the patient developed MGRS triggered by acute hepatitis E in less than a month. Second, the MGRS lesion was manifested in the form of light chain cast nephropathy.