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A1582 - Pulmonary Only Light Chain Deposition Disease in a Young Healthy Male
Author Block: M. Rendo1, M. Peterson2, J. Renshaw2; 1Internal Medicine, San Antonio Uniformed Services Health Education Consortum, Ft. Sam Houston, TX, United States, 2Hematology and Oncology, San Antonio Uniformed Services Health Education Consortum, Ft. Sam Houston, TX, United States.
Light chain deposition disease (LCDD) is a condition resulting in the deposition of immunoglobulin light chains in tissues. Seventy-five percent of cases are associated with a plasma cell dyscrasia.While multi-organ disease is most commonly seen, it has rarely been observed in a young, otherwise healthy patient with solely pulmonary involvement.
The patient is a twenty-eight year old male soldier with no past medical history who developed increasing cough and dyspnea over one year. His symptoms progressed to the point he was unable to pass a physical fitness test. Pulmonary function testing showed a restrictive pattern without bronchodilator response. Chest computed tomography (CT) imaging illustrated diffuse thin-walled cystic structures amongst scattered nodules with a basilar predominance. Cystic fibrosis polymerase chain reaction was negative. Serum protein electrophoresis showed hypergammaglobulins without an M-spike. Kappa and Lambda free light chains were elevated with a normal ratio and without proteinuria. A wedge surgical lung biopsy returned with follicular hyperplasia of bronchial associated lymphoid tissue with a plasma cell infiltrate. Congo red staining was without apple-green birefringence. Electron microscopy did not identify light chains. Nonetheless, the specimen had none of the nodules or cysts seen on imaging. A bone marrow biopsy showed fifty-percent cellularity without a monoclonal population. However, a cytogenetic abnormality of a 16q deletion was detected by FISH in 8.5% of the nuclei. While this indicated a plasma cell clone, he had no bone marrow light chain deposition, and met no multiple myeloma criteria. The clinical findings of cystic lung changes with elevated free light chains with normal renal function and a plasma cell clone on bone marrow biopsy favors the diagnosis of light chain deposition disease of the lung. He was started on therapy for a plasma cell dyscrasia with bortezomib, lenalidomide, and dexamethasone.
LCDD with solely pulmonary involvement is an extremely rare condition with only a few previous documented instances. While nodular light chain deposition is indolent, primarily cystic disease has progressed to respiratory failure in previous cases. Pulmonary light chain deposits are histologically similar to amyloid, however are not congophilic. While LCDD is commonly associated with multiple myeloma and renal impairment, neither feature was present. There are no established guidelines for this entity, and therapy was directed toward plasma cells. This is amongst the first documented instance of its use for primarily pulmonary LCDD.