Unusual manifestation of crystalline light chain tubulopathy in patient with multiple myeloma: case report and review of the literature

Abstract

Multiple myeloma (MM) is the second most common hematological malignancy, with an annual incidence in Europe and the USA of about 4-6 cases per 100,000. Several forms of renal disease are found in the course of MM, including: cast nephropathy, light chain (LC) deposition disease and primary amyloidosis. Less frequent forms include: acute and chronic tubulopathies, neoplastic plasma cell infiltration and interstitial nephritis. In this paper, we discuss a case of 53-year-old male patient with MM who presented with massive proteinuria (24 g/24 h), mild renal insufficiency (eGFR 43 mL/min), and Fanconi-like syndrome (as reflected by normoglycemic glycosuria). In kidney biopsy glomeruli were normal, whereas abundant AFOG-positive deposits were found in the cytoplasm of proximal tubular epithelial cells. These deposits were strongly positive for kappa light chains on immunofluorescence. Electron microscopy revealed electron-dense, intracytoplasmic crystalloid deposits of variable shape (needle-shaped, round and rectangular), and size in the proximal tubular cells. This unusual variant of microscopic renal lesions in the course of MM coupled with coincidence of Fanconi-like and nephrotic syndrome as a clinical manifestation has not been reported to date.

Crystalloid podocytopathy with focal segmental glomerulosclerosis in PCM: a case report

“…Light chains secreted by monoclonal plasma cells are reabsorbed by proximal tubular epithelial cells, and on rare occasions, intracellular crystals are formed during this process. These crystals impair tubular function and disrupt overall reabsorption capabilities causing various aggressive symptoms such as glycosuria, aminoaciduria, hyperuricosuria, hyperphosphaturia, and hypercalciuria [ 13 ]. In most of these patients, kappa light-chains are typically involved as components of their monoclonal proteins [ 14 , 15 ].…”

“…This characteristic of Vk1 is due to germline mutations of O2/O12 or O8/O18 [ 14 ]. Among these genes, a major mutation of O2/O12 induces a nonpolar or hydrophobic residue at position 30, which represents complementarity-determining region L1 of light chains and forms a portion of the Ig antigen-binding site [ 13 , 14 ].…”

Renal Light Chain Deposition Associated with the Formation of Intracellular Crystalline Inclusion Bodies in Podocytes: A Rare Case Report

“…Deposition in the form of crystalloids is not common and deposition in podocytes represents the rarest form of crystal deposition. Among the types of renal damage caused by monoclonal light chains, 70% of these are renal tubular damage and approximately 30% are glomerular injury (1). Additionally, there may also be more than one type of damage.…”

Multiple myeloma with secondary amyloidosis: Dysphagia as the first symptom: A case report

“…[8] Accumulation of amyloid deposits in multiple organs predicts a poorer prognosis and different treatment compared to amyloid deposits in a single organ. [9,10] Despite impressive advances in the treatment of MM, MM-related AL is also considered an independent high-risk prognostic factor in patients with MM, even when there are no symptoms at the time of diagnosis. The heart is the most commonly affected organ, with cardiomyopathy occurring in 70% of AL patients.…”