The patient was diagnosed with free light chain multiple myeloma with cast nephropathy.
Cast nephropathy is more common in light chain myeloma.
The proteinuria in cast nephropathy is mostly monoclonal protein or Bence Jones proteinuria.
If cast nephropathy or acute proximal tubular damage is present, acute renal failure is a common manifestation.
5-11) There are some morphologic patterns that are readily recognizable at the light microscopic level, especially when the manifestations are florid, including that of myeloma cast nephropathy, nodular glomerulosclerosis associated with light or heavy chain deposition disease, and light and heavy chain (AL and AH) amyloidosis.
Tubular casts morphologically similar to those seen in myeloma light chain cast nephropathy
have been reported in association with sirolimus-induced acute renal failure.