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Presented by Mark Haas, M.D. and prepared by Carol Allan, M.D.
Case 5: A 59 year old African-American man presented to the emergency room in August, 2000 with a three day history of fatigue, nausea, and headaches.
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Week 74: Case 5
A 59 year old African-American man presented to the emergency room in August, 2000 with a three day history of fatigue, nausea, and headaches. His symptoms started the day after doing extensive and strenuous work in his yard. He has also noted a decrease in his urine output. In the ER, he was found to have a serum creatinine of 14.5 mg/dL. Urinalysis showed only trace protein (by dipstick) with rare RBCs. Medical history is remarkable for a five year history of hypertension, well controlled with medication. He also occasionally takes Advil for “arthritis”. He was admitted to the hospital and underwent a renal biopsy./images/Mh5.1.jpg
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Answer: Light chain cast nephropathy (“myeloma kidney”)
Histology: There are numerous tubular casts present, many of which show a “fractured” appearance and some of which have an associated intratubular cellular reaction, although multinucleated giant cells are not noted in this particular case. The surrounding interstitium is edematous but with only very mild interstitial inflammation. The glomeruli are relatively unremarkable. Immunohistochemical stains show the casts to stain strongly for kappa light chains but only very weakly for lambda light chains. There is no tubular basement membrane staining for kappa or lambda.
Discussion: Light chain cast nephropathy (LCCN) is the most common of the three major renal complications of monoclonal gammopathy; the other two are AL (primary) amyloidosis and light chain deposition disease. LCCN is often referred to as “myeloma kidney”, but not all patients who develop LCCN have multiple myeloma. In some patients, acute renal failure due to LCCN will be the first clinical sign of a monoclonal gammopathy or even of multiple myeloma. The diagnosis in this case came as a complete surprise to the patient’s nephrologist, who suspected acute tubular necrosis due to dehydration or rhabdomyolysis (the patient having done strenuous yard work on a hot August day) or interstitial nephritis due to his use of ibuprofen. LCCN must be considered in the differential diagnosis of acute renal failure of unknown etiology, especially in patients over the age of 50. In this case, dehydration most likely helped precipitate (no pun intended) the onset of the cast nephropathy. As an aside, it should be noted that urinary light chains are typically not picked up on dipstick; as such the patient was found to have only trace proteinuria despite considerable excretion of monoclonal kappa light chains.
Incorrect
Answer: Light chain cast nephropathy (“myeloma kidney”)
Histology: There are numerous tubular casts present, many of which show a “fractured” appearance and some of which have an associated intratubular cellular reaction, although multinucleated giant cells are not noted in this particular case. The surrounding interstitium is edematous but with only very mild interstitial inflammation. The glomeruli are relatively unremarkable. Immunohistochemical stains show the casts to stain strongly for kappa light chains but only very weakly for lambda light chains. There is no tubular basement membrane staining for kappa or lambda.
Discussion: Light chain cast nephropathy (LCCN) is the most common of the three major renal complications of monoclonal gammopathy; the other two are AL (primary) amyloidosis and light chain deposition disease. LCCN is often referred to as “myeloma kidney”, but not all patients who develop LCCN have multiple myeloma. In some patients, acute renal failure due to LCCN will be the first clinical sign of a monoclonal gammopathy or even of multiple myeloma. The diagnosis in this case came as a complete surprise to the patient’s nephrologist, who suspected acute tubular necrosis due to dehydration or rhabdomyolysis (the patient having done strenuous yard work on a hot August day) or interstitial nephritis due to his use of ibuprofen. LCCN must be considered in the differential diagnosis of acute renal failure of unknown etiology, especially in patients over the age of 50. In this case, dehydration most likely helped precipitate (no pun intended) the onset of the cast nephropathy. As an aside, it should be noted that urinary light chains are typically not picked up on dipstick; as such the patient was found to have only trace proteinuria despite considerable excretion of monoclonal kappa light chains.
