Fig 1

Histology of bone marrow trephine revealing amyloid deposition and monoclonal (lambda light chain restricted) plasma cell infiltration. a)H&E of bone marrow. Interstitial infiltrate of atypical plasma cells with numerous Russell and Dutcher bodies (intracyto plasmic and intranuclear inclusions of immunoglobu lin within plasma cells). Arrow pointing to Dutcher body, which is supportive of a neoplastic plasma cell. b)Sirius Red stain for amyloid, demonstrating positivity within blood vessel walls in the marrow (arrow). c)In situ hybridisation for lambda immunoglobulin light chain (approximately 15% of cells are positive) d)In situ hybridisation for kappa immunoglobulin light chain (very scanty positive cells)