We describe a case of solitary myeloma showing cystic change filled with massive crystalline structures in a 54-year-old woman. A bone X-ray showed a solitary cystic osteolytic lesion in the right iliac bone. Serum and urine protein electrophoresis showed no demonstrable M-protein, and bone-marrow aspirates did not show any myeloma cells. Histologic examination of the tumor revealed aggregation of plasma cells with massive extracellular infiltration of the rhomboid-shaped crystalline structures. In immunoperoxidase staining, both these crystalline structures and the cytoplasms of the myeloma cells demonstrated a positive reaction for lambda light chain. By electron microscope, the large extracellular crystalline structures were observed, and we found unique rhomboid or rectangular-shaped crystalline structures in the cytoplasms of the myeloma cells.
Bone Neoplasms/immunology/*ultrastructure ; Crystallization ; Extracellular Space/immunology ; Female ; Humans ; Immunoglobulin lambda-Chains/ultrastructure ; Microscopy, Electron ; Middle Aged ; Plasmacytoma/immunology/*ultrastructure

Adult ; Aged ; Amyloidosis ; metabolism ; pathology ; Biopsy ; Female ; Humans ; Immunoglobulin Light-chain Amyloidosis ; Immunoglobulin kappa-Chains ; metabolism ; Immunoglobulin lambda-Chains ; metabolism ; Intestinal Mucosa ; pathology ; ultrastructure ; Kidney ; metabolism ; pathology ; ultrastructure ; Kidney Diseases ; metabolism ; pathology ; Male ; Middle Aged ; Rectum ; pathology ; ultrastructure ; Retrospective Studies

OBJECTIVETo investigate the pathologic features and diagnostic algorithm of light chain nephropathy (LCN).

METHODSSeven cases of LCN were studied by light microscopy, electron microscopy and immunolabeling of light chains (kappa, lambda) by immunofluorescence and immunoelectron microscopy.

RESULTSThe histopathology of 7 cases by light microscopy was variable, with 3 cases showing nodular glomerulosclerosis, 1 case showing mild to moderate mesangial proliferation, and 3 cases showing cast nephropathy with minimal glomerular change. Immunofluorescence study revealed positive staining of a single type of light chain in mesangium (nodular pattern) or along glomerular basement membrane (linear), along tubular basement membrane and around arteriolar walls in all the 7 cases. Ultrastructurally, electron-dense granular deposits were identified in mesangium, subendothelial aspect of glomerular basement membrane, outer aspect of tubular basement membrane and arteriolar walls. Immunogold labeling of light chains showed distinct labeling of a single type light chain in the granular electron-dense materials (5 cases being kappa-positive and 2 being lambda-positive).

CONCLUSIONSLCN typically shows nodular glomerulosclerosis. The ultrastructural change is characteristic and important for diagnosis. Immunolabeling of light chains by immunofluorescence and immunoelectron microscopy carries further diagnostic value, especially in cases with minimal light microscopic change.

Adult ; Aged ; Female ; Glomerulosclerosis, Focal Segmental ; immunology ; pathology ; Humans ; Immunoglobulin Light Chains ; immunology ; Immunoglobulin kappa-Chains ; immunology ; Immunoglobulin lambda-Chains ; immunology ; Kidney Diseases ; immunology ; pathology ; Kidney Glomerulus ; immunology ; pathology ; ultrastructure ; Male ; Microscopy, Fluorescence ; Microscopy, Immunoelectron ; Middle Aged