Light chain proximal tubulopathy without crystals in a case of Burkitt lymphoma presenting with acute kidney injury

Coincidental light chain induced proximal tubulopathy with lupus nephritis: a case report and review of the literature

Background

We report a case of light chain proximal tubulopathy associated with lupus nephritis in a patient known to have systemic lupus erythematosus. The kidney can be injured in several ways in any of these disorders. Light chain proximal tubulopathy is a rare form of renal tubular injury that may occur in and complicate plasma cell dyscrasia, characterized by cytoplasmic inclusions of the monoclonal light chain within proximal tubular cells. Lupus nephritis is a common form of renal injury as it occurs in about 25–50% of adult patients with systemic lupus erythematosus.

Case presentation

We present a 57-year-old African patient known to have systemic lupus erythematosus and hypertension presented with a new complaint of microscopic hematuria. A renal biopsy was performed and revealed lupus nephritis class II concurrently associated with light chain induced proximal tubulopathy. A subsequent bone marrow biopsy was performed, which revealed multiple myeloma.

Conclusions

We report a case of coincidental lupus nephritis and proximal tubulopathy featuring a combined constellation of rare histopathological features that might add to the relationship between systemic lupus and paraproteinemia.

Tubular Injury and Dendritic Cell Activation Are Integral Components of Light Chain-Associated Acute Tubulointerstitial Nephritis

CONTEXT.—

Light chain-associated acute tubulointerstitial nephritis (LC-ATIN) is a variant of light chain proximal tubulopathy (LCPT). It is characterized by interstitial inflammation with tubulitis and deposition of monoclonal light chains in the tubulointerstitium. LC-ATIN is a rather poorly recognized pattern of LCPT and not much is known about this entity.

OBJECTIVE.—

To determine the clinicopathologic features of patients with LC-ATIN and investigate the proximal tubular injury and mechanism of interstitial inflammation in LC-ATIN.

DESIGN.—

A total of 38 cases of LC-ATIN were identified from the archives of 5043 renal biopsy specimens. In all cases, routine light microscopic examination, immunofluorescence, and electron microscopic examination were performed. In selected cases, immunofluorescent staining of dendritic cells and immunohistochemical staining for 4 tubular injury markers-KIM-1, p53, bcl-2, and Ki-67-were performed.

RESULTS.—

A characteristic finding in LC-ATIN cases was immunofluorescence staining of monoclonal light chains along tubular basement membranes in linear fashion and inside proximal tubular cells with a granular pattern. No monoclonal light chains were present in glomerular or vascular compartments confirmed with immunofluorescence, electron microscopy, and ultrastructural gold labeling. Ten of 15 LC-ATIN cases (67%) were concurrently positive for the 4 tubular injury markers. Dendritic cells were identified within the tubulointerstitium in the renal biopsy specimens, interacting with surrounding tubules with light-chain deposits and inflammatory cells.

CONCLUSIONS.—

Significant proximal tubular injury occurs associated with LC-ATIN, and the monoclonal light chains accumulated in proximal tubular cells contribute to the injury. Dendritic cells are involved in the pathogenesis of interstitial inflammation in LC-ATIN.

Light chain proximal tubulopathy with cast nephropathy in a case of multiple myeloma

The renal diseases most frequently associated with myeloma include cast nephropathy (CN), amyloidosis and monoclonal immunoglobulin deposition disease. Light chain proximal tubulopathy (LCPT) is reported less frequently. Majority of the cases with κ-restriction present with Fanconi syndrome (FS) and show crystals in proximal tubular epithelial cytoplasm. In contrast, those with λ-restriction are infrequently associated with FS and show cytoplasmic vacuolations in proximal tubular epithelial cytoplasm. Combination of morphologies in kidney affected by plasma cell dyscrasias is rare and co-existence of LCPT and CN is one of the rarest. We report a case of multiple myeloma having this rare combination of morphologies.

Acute kidney injury in lymphoma: a single centre experience

Background. Acute kidney injury (AKI) is a common but least studied complication of lymphoma. Objective. To determine the frequency and predictors of AKI in lymphoma and to study the impact of AKI on hospital stay and mortality. Methods. Retrospective review of medical records of hospitalized lymphoma patients aged ≥14 years between January 2008 and December 2011 was done. Results. Out of 365 patients, AKI was present in 31.8% (116/365). Multivariate logistic regression analysis showed that independent predictors for AKI included sepsis (odds ratio (OR) 3.76; 95% CI 1.83-7.72), aminoglycosides (OR 4.75; 95% CI 1.15-19.52), diuretics (OR 2.96; 95% CI 1.31-6.69), tumor lysis syndrome (OR 3.85; 95% CI 1.54-9.59), and R-CVP regimen (OR 4.70; 95% CI 1.20-18.36). AKI stages 2 and 3 was associated with increased hospital stay (OR 2.01; 95% CI 1.19-3.40). Conclusion. AKI was significantly associated with sepsis, aminoglycoside, diuretics, presence of tumor lysis syndrome, and use of R-CVP regimen. Presence of AKIN (Acute Kidney Injury Network) stages 2 and 3 AKI had increased hospital stay. AKI was also associated with increased mortality.

Acute kidney injury as first presentation of lymphoma: the role of renal biopsy

A 65-year-old man with an insidious history of being generally unwell with weight loss, a poor appetite and night sweats was transferred to a tertiary nephrology unit after being found to be in acute kidney injury (AKI). A renal biopsy was performed on the same day which revealed lymphomatous infiltration of the renal parenchyma. He required temporary haemodialysis as he was oliguric and was started on chemotherapy. His renal function improved to baseline 3 weeks after treatment. This case illustrates the uncommon presentation of direct lymphomatous infiltration as a cause of AKI and the integral role of renal biopsy in ascertaining the diagnosis.