A case of monoclonal immunoglobulin light- and heavy-chain deposition disease exhibiting atypical deposition with fibrillary structures, successfully treated with chemotherapy

Renal diseases with organized deposits: an algorithmic approach to classification and clinicopathologic diagnosis

CONTEXT

Most renal diseases with organized deposits are relatively uncommon conditions, and proper pathologic characterization determines the specific diagnosis. Different entities with specific clinical correlates have been recognized, and their correct diagnosis has an impact on patient management, treatment options, and determination of prognosis.

OBJECTIVE

The diagnosis of these conditions depends on careful evaluation of the findings by light microscopy together with immunofluorescence and electron microscopy. The objective of this manuscript is to delineate an algorithmic approach helpful in the pathologic assessment of these conditions at the light microscopic level. In some diseases, the immunomorphologic parameters short of electron microscopy provide solid information to suggest or make a definitive diagnosis. Nevertheless, electron microscopy plays a crucial role, because the criteria to separate these entities often are heavily influenced by the electron microscopic findings. Accepted diagnostic criteria for each of these conditions are discussed.

DESIGN

Information used for this manuscript is gathered from published data and the authors' experience.

RESULTS

The most common of these conditions is amyloidosis, which may account for as many as 5% to 8% of all renal biopsies in some renal pathology practices. Fibrillary, immunotactoid, and cryoglobulinemic glomerulopathies together represent, at most, 1% of all renal biopsies performed for medical renal diseases. Diabetic fibrillosis also is uncommon. Glomerulopathies associated with fibronectin deposits and collagenofibrotic glomerulopathy are extremely rare.

CONCLUSIONS

A systematic, algorithmic approach to the evaluation of the renal biopsies from patients with these disorders is very helpful to rule out certain conditions in the early stages of the evaluation of the biopsies. However, it is not uncommon for the final definitive diagnosis to be reached only after electron microscopic evaluation.

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.