Spectrum of Kidney Biopsy Findings Associated With Methamphetamine Use.

Introduction: Methamphetamine (METH) is one of the most used drugs of abuse worldwide. However, there are few reports and series examining the toxic kidney effects of METH, and associated histopathological changes are not well-described. Methods: We retrospectively identified 112 patients with a history significant for METH abuse, of whom 62 were using METH-only and 60 were using METH plus other drugs of abuse. Results: In the METH-only cohort, the mean age was 41 years (interquartile range [IQR]: 33-49) and most (76%) were male. Almost all cases (97%) showed evidence of kidney dysfunction at the time of biopsy. Of the cases, 65% had proteinuria, of which 53% were nephrotic range and 10% had nephrotic syndrome. The most common biopsy diagnosis was acute tubular necrosis (ATN) (66%), of which 19% had myoglobin casts; followed by focal segmental glomerulosclerosis (FSGS) in 53% (not otherwise specified [NOS] in 76% and collapsing FSGS [cFSGS] in 18%). Biopsy findings also include tubulointerstitial nephritis (TIN) (37%), thrombotic microangiopathy (TMA) (24%), and diabetic glomerulosclerosis (DG) (31%). Glomerulonephritis (GN) was identified in one-third of cases, the most common of which were infection-related GN (IRGN) (15%) and IgA nephropathy (IgAN) (11%). Of those with GN, 64% had underlying infection. Of interest, there was increased association for myoglobinuric ATN in those with concurrent ethanol-abuse (P = 0.002). Moreover, the METH-only patients were more likely to have DG compared to those with multiple substance-use (P = 0.01). More than half of the patients demonstrated at least moderate to severe tubulointerstitial scarring and marked hypertensive vascular disease. Conclusion: Most patients with METH-use present with acute kidney injury (AKI) and often have proteinuria associated with a wide spectrum of renal pathology.

An Unusual Case of Multiple Myeloma with Light-Chain Cast Nephropathy Secondary to a Very Large Plasmacytoma without Bone Marrow Involvement.

Here, we report a case of a patient who presented to Strong Memorial Hospital with new-onset renal failure and anemia and was found to have multiple myeloma with lambda light-chain cast nephropathy secondary to a very large (14 cm × 14 cm × 12 cm) plasmacytoma without bone marrow involvement. This case is notable as solitary plasmacytomas are almost never seen with concomitant myeloma-defining CRAB criteria or significantly elevated serum free light-chain ratios. Although solitary plasmacytomas are typically definitively treated with radiation, this case highlights that systemic treatment may be helpful in certain clinical scenarios.