Disclaimer: This article serves as an informational resource and is not a substitute for professional medical advice or a diagnosis from a qualified healthcare provider.
Light-chain deposition disease (LCDD) is an uncommon condition that predominantly manifests in individuals around their sixth decade of life. LCDD primarily affects the kidneys, although other organs can also be impacted.
Our immune system generates antibodies, or immunoglobulins, as a defense mechanism to identify and combat foreign invaders, such as bacteria and viruses (known as antigens). These immunoglobulins possess a Y-shaped structure and are typically comprised of two heavy and two light chains. The body of the Y is formed by the two heavy chains, while the two light chains attach on the left and right sides of the Y’s arms. This combined structure creates a unique shape at each tip of the Y, specifically designed to capture a particular antigen, akin to how a key fits into a lock.
LCDD arises when plasma cells, a type of white blood cell found in the bone marrow, start producing excessive light chains in an uncontrolled manner. These light chains circulate in the bloodstream and subsequently accumulate in various organs. While the kidneys are consistently affected, deposits can also form in the liver, heart, small intestine, spleen, skin, nervous system, and bone marrow.
LCDD is a rare condition, and its precise prevalence remains unknown. While it can occur in individuals aged between 30 and 90, it most frequently presents after the age of 60, with males appearing to be more susceptible than females. Approximately 50 to 60 percent of individuals diagnosed with LCDD also have multiple myeloma, a cancer involving plasma cells in the bone marrow. Others may not have coexisting blood disorders or may receive a diagnosis of monoclonal gammopathy of unknown significance (MGUS), a condition characterized by abnormal protein production by plasma cells.
Within the kidneys, LCDD triggers glomerulosclerosis, which is the scarring of the tiny blood vessels in the kidneys. Signs and symptoms encompass nephrotic syndrome with proteinuria, reduced levels of blood serum protein, elevated blood lipid levels, and edema or swelling. The loss of kidney function closely resembles that seen in diabetic kidney disease. When the heart is affected, it can result in enlargement, congestive heart failure, and irregular heartbeats. Liver deposits typically remain asymptomatic, but in rare instances, liver failure has been reported. Involvement of the nervous system may lead to peripheral neuropathy, characterized by pain, sensory loss, or impaired muscle control. Skin lesions can develop if light chains are deposited in the skin.
LCDD is often detected when individuals are assessed for proteinuria or nephrotic syndrome, and a renal biopsy is performed. During this procedure, a small sample of kidney tissue is examined using an electron microscope, revealing the presence of light chain deposits. Around 85 percent of LCDD patients exhibit light chains in their blood or urine, detectable through tests measuring immunoglobulin levels. In cases where light chains are absent from blood or urine, a bone marrow aspirate may be conducted to identify abnormal plasma cell quantities or significant light chain presence. Staining the bone marrow with fluorescent dye allows for microscopic examination of defective plasma cells.
The primary objective of LCDD treatment is to reduce the population of plasma cells responsible for overproducing immunoglobulin light chains. This may involve chemotherapy or, in certain cases, a stem cell transplant. Initially, a patient’s own stem cells are collected and preserved from either the blood or bone marrow. Subsequently, the patient undergoes high-dose chemotherapy to eradicate abnormal plasma cells. Following this, the preserved stem cells are reintroduced into the bloodstream, where they migrate to the bone marrow and begin producing healthy plasma cells.
In cases where LCDD progresses to kidney failure, dialysis becomes necessary to compensate for lost kidney function. A kidney transplant may be considered, but it is crucial to note that the risk of LCDD recurrence in the transplanted kidney can be as high as 80 percent. Therefore, a stem cell transplant is typically a prerequisite for individuals with LCDD seeking a kidney transplant.
