Abstract Introduction Pulmonary light chain deposition disease (PLCDD) is a rare disorder characterized by localized deposition of non-amyloid monoclonal immunoglobulin light chains within the lung parenchyma, pathologically distinct from pulmonary amyloidosis. Unlike systemic LCDD, which commonly affects the kidneys, heart, and lungs, isolated PLCDD lacks extra-pulmonary organ involvement and its etiology remains unclear. Fewer than 50 cases have been reported so far. Clinical presentation is non-specific, making diagnosis challenging and dependent on tissue biopsy. We describe a rare case of isolated PLCDD presenting as multiple “popcorn-like” pulmonary nodules. Case Presentation A 76-year-old woman with Alzheimer’s disease, hypertension, hypothyroidism, and osteoarthritis was evaluated for chronic cough. CT chest revealed multiple pulmonary nodules, initially detected 6 years earlier with slow interval growth, raising suspicion for a low-grade neuroendocrine tumor. CT chest/abdomen/pelvis showed no metastatic disease. FDG-PET demonstrated avid pulmonary nodules with concern for “popcorn” like appearance. CT-guided biopsy revealed amorphous material with associated multinucleated giant cell reaction and chronic inflammation. Congo red staining was negative with no evidence of granulomatous inflammation. Given this, further testing was undergone with pathology re-review showing mild lymphoplasmacytic proliferation with surrounding amorphic eosinophilic material consistent with kappa light chain deposition disease. Given rarity of pulmonary only disease; evaluation for systemic disease was then undergone with 24hr urine testing and laboratory evaluation for plasma cell dyscrasias. Work up thus far has been negative. . Discussion PLCDD is an uncommon cause of pulmonary nodules and may mimic neoplastic, infiltrative, or cystic lung diseases. Histopathology with Congo red staining and serum light chain profiling are essential for distinguishing PLCDD from amyloidosis and systemic LCDD. If concern arises for PLCDD it is imperative to undergo multidisciplinary discussions with pathology for further testing and to undergo systemic evaluation primarily to rule out renal involvement; systemic plasma cell dyscrasias such as amyloid or myeloma; and even a bone marrow biopsy to rule out lymphomatous processes that could be underlying the light chain deposition. PLCDD is a rare and underdiagnosed condition and therefore early recognition and awareness are critical This abstract is funded by: None
Poojary et al. (Fri,) studied this question.