What are the Monoclonal immunoglobulin deposition disease (MIDD)?
The Monoclonal immunoglobulin deposition disease (which are now considered within the MGRS classification of disease) describe another histologic and clinical variant of abnormal tissue deposition resulting from a monoclonal-free LC (or, rarely, the heavy chain [HC] component of Ig alone or in combination with LC), which has some characteristics similar to amyloidosis in that abnormal extracellular protein deposition occurs, yet the microstructure differs because these proteins do not form fibrils and the deposits do not stain with Congo red. Typically, light chain deposition disease (LCDD) (also known as Randall’s disease) is associated with specific variants of the κ-LC variable region domain (types I and IV), which bind strongly and accumulate along the tubular and glomerular basement membrane, but also deposit in the mesangium where they induce the production of extracellular matrix and typical nodular glomerular lesions. The clinical presentation of both LCDD and heavy chain deposition disease (HCDD) is similar, and is usually with a glomerulonephritis or nephritic picture: hypertension, hematuria, and proteinuria with kidney impairment. Cardiac and hepatic involvement may also occur. Therapy is directed toward treatment of the LC with steroids and myeloma chemotherapy including ASCT, and clinical response is variable. Kidney transplantation has a high risk of recurrent disease.
