Immunotactoid glomerulopathy with massive bone marrow deposits in a patient with IgM kappa monoclonal gammopathy and hypocomplementemia

A Rare Case of Recurrent Immunotactoid Glomerulonephritis

Immunotactoid glomerulopathy is an uncommon cause of glomerular disease that results from deposits derived from immunoglobulins. This rare disease can occur in native kidneys and in transplant patients. They are present only in 0.5% to 1.4% of native kidney biopsies. Treatment of this disease is directed at the underlying monoclonal gammopathy, infection, and B-cell lymphoproliferative disorders. Prognosis is very guarded with 50% of people developing ESRD within five years of diagnosis. We present an interesting, rare case of recurrent immunotactoid glomerulonephritis which responded appropriately to rituximab therapy.

Long-term clinical course of immunotactoid glomerulopathy complicated with diffuse large B-cell lymphoma

We report a case of immunotactoid glomerulopathy (ITG) complicated with diffuse large B-cell lymphoma (DLBCL). A 68-year-old woman presented with leg edema and was diagnosed with nephrotic syndrome (NS). Renal biopsy revealed ITG. We treated the patient with prednisolone (20 mg/day) and she achieved complete remission of NS. Steroids were gradually reduced. After 1 year, the patient presented with a breast mass determined on biopsy to be DLBCL. She underwent six cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) therapy. Follow-up revealed complete remission of both DLBCL and ITG. NS recurred after 5 years and she was simultaneously diagnosed with recurrence of DLBCL in bone marrow. She underwent four cycles of R-EPOCH (rituximab, etoposide, prednisolone, vincristine, cyclophosphamide, doxorubicin) therapy and entered remission for DLBCL. NS improved, but the treatment did not lead to remission. After 2 additional years, NS and DLBCL recurred again. She was administered rituximab and NS improved, although proteinuria tended to increase thereafter. One year later, we started prednisolone (10 mg/day), and proteinuria tended to decrease. She is currently undergoing outpatient follow-up. This case suggests that ITG with MGUS should be treated with the possibility of developing malignant hematological disease during the course.

The Continuing Need for Electron Microscopy in Examination of Medical Renal Biopsies: Examples in Practice

Background

For the better part of the past 6 decades, transmission electron microscopy (EM), together with routine light microscopy and immunofluorescence and/or immunohistochemistry (IHC), has been an essential component of the diagnostic workup of medical renal biopsies, particularly native renal biopsies, with increasing frequency in renal allograft biopsies as well. Studies performed prior to the year 2000 have indeed shown that a substantial fraction of renal biopsies cannot be accurately diagnosed without EM. Still, EM remains costly and labor-intensive, and with increasing pressure to reduce healthcare costs, some centers are de-emphasizing diagnostic EM. This trend has been coupled with advances in IHC and other methods in renal biopsy diagnosis over the past 2-3 decades.

Summary

Nonetheless, it has been our experience that the diagnostic value of EM in the comprehensive evaluation of renal biopsies remains similar to what it was 20-30 years ago. In this review, we provide several key examples from our practice where EM was essential in making the correct renal biopsy diagnosis, ranging from relatively common glomerular lesions to rare diseases.

Key Messages

EM remains an important component of the diagnostic evaluation of medical renal biopsies. Failure to perform EM in certain cases will result in an incorrect diagnosis, with possible clinical consequences. We strongly recommend that tissue for EM be taken and stored in an appropriate fixative and ultrastructural studies be performed for all native renal biopsies, as well as appropriate renal allograft biopsies as recommended by the Banff consortium.

Thrombotic microangiopathy with intraglomerular IgM pseudothrombi in Waldenström macroglobulinemia and IgM monoclonal gammopathy

IgM secreting myelomas or lymphomas, including Waldenström macroglobulinemia, are associated with a varied spectrum of renal pathology, including intracapillary hyaline deposits, cryoglobulin, membranoproliferative glomerulonephritis, amyloid, monoclonal immunoglobulin deposition disease, cast nephropathy, and lymphoma infiltration. We report our single institution experience, and describe five cases with distinctive glomerular pathology: intracapillary IgM pseudothrombi and thrombotic microangiopathic change, with glomerular intracellular crystals in two biopsies. Two patients were hypocomplementemic at presentation. This series adds to the recent literature on paraprotein associated thrombotic microangiopathy.

Monoclonal light chain deposits within the stomach manifesting as immunotactoid gastropathy

Immunotactoid deposits are defined by their ultrastructural appearance and are characterized by microtubular or cylindrical structures typically measuring greater than 30 nm in diameter. Although a rare entity, immunotactoid deposition most often manifests as immunotactoid glomerulopathy and is associated with underlying lymphoplasmacytic disorders. Corneal immunotactoid deposition known as immunotactoid keratopathy has also been reported in patients with paraproteinemia. Here, we describe the first reported case of immunotactoid deposition in the stomach. The deposits were composed solely of kappa immunoglobulin light chains without significant lambda light chain or immunoglobulin heavy chain components. The patient displayed no renal signs or symptoms, and additional thorough clinical examination failed to detect any evidence of a paraproteinemia or plasma cell dyscrasia. Thus, the gastric immunotactoid deposits in this case appear to be an isolated finding of light chain deposition, of which the significance and etiology are unclear.

Proliferative glomerulonephritis with monoclonal IgM-κ deposits in chronic lymphocytic leukemia/small lymphocytic leukemia: case report and review of the literature

A 48-year-old man with chronic lymphocytic leukemia presented with nephrotic syndrome, hematuria, and mild deterioration of renal function. Further analysis using serum immunofixation electrophoresis detected monoclonal immunoglobulin (Ig) M-κ and IgG-κ M-protein. Testing for cryoglobulin in serum was negative. Light microscopy of a renal biopsy specimen showed membranoproliferative glomerulonephritis features with marked mononuclear cell infiltration in the interstitium. On immunofluorescence study, the deposition of IgM heavy chain was predominantly observed with the same distribution of κ light chain, whereas no λ light chain was found. Electron microscopy revealed fine granular deposits in the mesangial, subendothelial, and subepithelial areas, mimicking those observed in the immune complex-mediated glomerulonephritis. These pathological findings were consistent with recently described cases of proliferative glomerulonephritis with monoclonal IgG deposits. Thus, monoclonal IgM deposition can also cause proliferative glomerulonephritis.

A case of immunotactoid glomerulopathy exhibiting nephrotic syndrome successfully treated with corticosteroids and antihypertensive therapy

We report a case of immunotactoid glomerulopathy (ITG) with cerebral hemorrhage and hypocomplementemia, with successful therapeutic outcome following the corticosteroids and antihypertensive treatment. A 70-year-old man presented with facial edema in October 2006. One day prior to his referral, he experienced speech disturbance, headache, and vomiting, and on the next day he was referred to our hospital. The laboratory examination revealed massive proteinuria (11.3 g/day) and hematuria. The total serum hemolytic complement (CH50) was decreased to 23 U/ml and C4 component was decreased to 7.5 mg/dl, whereas C3 component remained within normal limits (82 mg/dl). Brain computed tomography scan showed high-density lesions in the left parieto-occipital area suggesting subcortical cerebral hemorrhage. Renal biopsy revealed diffuse subendothelial PAS-positive depositions. Immunofluorescence studies revealed intensive deposition of IgG, IgA, C3, C1q, Fibrinogen, and kappa light chain with granular pattern in the capillary and mesangial area. Electron microscopic examination revealed regularly arranged microtubular deposits, appearing as 21-33 nm in diameter. Based on these findings, this patient was diagnosed as ITG complicated with cerebral hemorrhage and hypocomplementemia. He received oral prednisolone (30 mg/day), resulting in reduction of proteinuria, improvement of hypocomplementemia, and prevention of renal functional deterioration. This case demonstrates that accurate diagnosis of ITG may result in successful therapeutic outcome.

Renal lesions associated with IgM-secreting monoclonal proliferations: revisiting the disease spectrum

BACKGROUND AND OBJECTIVES

Since the first description of pathology of the kidney in Waldenström disease in 1970, there have been few reports on kidney complications of IgM-secreting monoclonal proliferations. Here, we aimed to revisit the spectrum of renal lesions occurring in patients with a serum monoclonal IgM.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Fourteen patients with a circulating monoclonal IgM and a kidney disease related to B cell proliferation were identified retrospectively. Demographic, clinical, and laboratory data were assessed for each patient at the time of kidney biopsy.

RESULTS

Seven patients had a nephrotic syndrome. Patients without nephrotic syndrome all had impaired renal function. Mean serum creatinine was 238 micromol/L. For five patients, the diagnosis of monoclonal IgM preceded the kidney disease by 28.8 mo (range 12 to 60). Seven patients had Waldenström disease, two had a small B cell non-Hodgkin lymphoma, one had an IgM-excreting multiple myeloma, one had a marginal zone B cell lymphoma, and three had an IgM-related disorder. Renal lesions included (1) intracapillary monoclonal deposits disease with granular, electron-dense IgM thrombi occluding capillary lumens (5); (2) atypical membranoproliferative glomerulonephritis (3); (3) lambda light chain amyloidosis (2) associated with mu deposits in one patient; (4) acute tubular necrosis (1); and (5) CD20(+) lymphomatous infiltration (3). Remission of the nephrotic syndrome was attained in three of seven patients, and renal function improved after chemotherapy.

CONCLUSIONS

Although renal complications of IgM proliferations are rare, a wide spectrum of kidney lesions is observed, without correlation with the type of hematologic disorder.

A case of fibrillary glomerulonephritis with unusual IgM deposits and hypocomplementemia

Fibrillary glomerulonephritis (FGN) is rare immune-mediated GN with predominant immunoglobulin (Ig) G deposits, normal serum complement levels, and poor prognosis. The incidence of FGN is less than 1% in the adult population, and only six pediatric cases have been reported in the English literature. A 12-year-old girl presented with acute nephrotic-nephritic syndrome mimicking atypical clinical features of acute poststreptococcal GN (APSGN). Clinical features had completely resolved in 2 weeks, but the serum complement levels remained low. Renal biopsy was done 6 months later, and she was diagnosed as having FGN with unusual IgM deposits. Despite persistently low serum complement levels during the subsequent 3 years, clinical relapse did not develop. This case was an atypical form of FGN characterized by unusual IgM deposits, persistent hypocomplementemia, and good prognosis, which suggests that childhood FGN is not necessarily a disease with poor prognosis.

Pathology of glomerular deposition diseases

In routine diagnosis on renal biopsy, one of the confusing fields for pathological diagnoses is the glomerulopathies with fibrillary structure. The primary glomerulopathies with a deposit of ultrastructural fibrillary structure, which are negative for Congo-red stain but positive for immunoglobulins, include fibrillary glomerulonephritis and immunotactoid glomerulopathy. Several paraproteinemias including cryoglobulinemia, monoclonal gammopathy, and light chain deposition disease as well as hematopoietic disorders including plasmacytoma, plasma cell dyscrasia, and B cell lymphoproliferative disorders involve glomerulopathy with an ultrastructural fibrillary structure. A rare glomerulopathy with fibrillary structure that stains negative for Congo-red as well as for immunoglobulins has been also reported. The pathological diagnoses of these glomerulopathies can include either glomerular diseases, or paraproteinemic diseases, or hematopoietic diseases. The terminology is still confusing when glomerular diseases can be combined with paraproteinemic diseases and/or hematopoietic diseases. Therefore, the generic term, 'glomerular deposition disease' (GDD), has been proposed by pathologists with a requirement for clinicians to detect autoantibodies, paraproteins as well as to carry out a bone marrow check. An attempt has been made to rearrange the diseases with related disorders of fibrillary deposits, based on detailed clinical and pathological finding and to elucidate the correlation between GDD, paraproteinemia, and hematopoietic disorder.

Unusual IgM fibrillar deposits in glomerulonephritis: ultrastructural and diffraction studies in a case report

Morphological examination of 2 renal biopsy specimens obtained from a 69-year-old woman with a nephrotic syndrome, high blood pressure, and a reduced glomerular filtration rate revealed, in ultrastructural study, a type of a glomerulonephritis with fibrillar deposits in a subendothelial position which were unusual in their immunoglobulin components (mainly IgM). The fibrillar components were of irregular size, 13 to 18 nm in diameter and presented a very particular "barbed wire" morphological aspect, not hitherto described. Diffraction studies and image analysis, revealed spiraled fibrils with regular alternating elements that we suggest may correspond to IgM molecules. The clinical (isolated renal symptoms) and laboratory (traces of 3 monoclonal components in the serum and 2 normal bone marrow biopsy specimens) data provided no evidence of hematopoietic malignancy, viral hepatitis or cryoglobulinemia.