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Diagnose This (July 6, 2020)

Joel Murphy, MD
By Joel Murphy, MD

Jul 07, 2020

light chain deposition disease, Diagnose This, Arkana Laboratories, renal pathology
AMT Camera System 6/2/2020 14:50 12000 7.0 60 Imaging KW1 KW2 20765.4 342754.1 0 XpixCal=175.195000 YpixCal=175.195000 Unit=um ##fv3 2048 2464 7.0.1.99 Blank1 Blank2 ##fv4

What is your diagnosis based on the EM image provided?

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The electron microscopy image provided is that of a proximal tubule and demonstrates confluent “powdery” or “pellet-like” deposits along the tubular basement membrane consistent with a diagnosis of light chain deposition disease (LCDD), the most common subtype of monoclonal immunoglobulin deposition disease (MIDD). By immunofluorescence, the case revealed diffuse, linear, 3+ staining for lambda light chain along tubular basement membranes as well as glomerular basement membranes while kappa light chain was completely negative. By light microscopy, glomeruli demonstrated a spectrum of mild to severe, early nodular, PAS-positive mesangial matrix expansion with a somewhat chunky appearance while tubules showed evidence of acute tubular injury.

As the name implies, MIDD is caused by the systemic deposition of monoclonal immunoglobulin along tubular and glomerular basement membranes and within the glomerular mesangium. The monoclonal immunoglobulin is typical of the light chain type but can also be due to the deposition of an abnormal heavy chain (HCDD) or even both, light and heavy chains (LHCDD). Of note, while most patients will demonstrate an abnormal SPEP/UPEP at the time of diagnosis, approximately 15-20% will have an undetectable paraprotein at that time. Regarding prognosis, renal survival is poor with a mean of around 5 years.

 

Quick note: This post is to be used for informational purposes only and does not constitute medical or health advice. Each person should consult their own doctor with respect to matters referenced. Arkana Laboratories assumes no liability for actions taken in reliance upon the information contained herein.