Abstract Introduction Light chain deposition disease (LCDD) is a rare hematologic disorder marked by non-amyloid monoclonal light chain deposits in multiple organs, most commonly affecting the kidneys. Pulmonary light-chain deposition disease (PLCDD) is a rare condition characterized by multiple lung cysts and nodules, often linked to lymphoid proliferative disorders. Case Presentation A 76-year-old female with medical history of hypertension and hypothyroidism presented with cough and generalized weakness for 2 months. She denied other pulmonary symptomatology. She denied any history of tobacco, alcohol, or recreational drug use, as well as any exposure to toxins or recent travel. Her home medications included donepezil, memantine, citalopram, lisinopril, and levothyroxine. Initial laboratory workup showed a WBC of 6.4 ×109/L, hemoglobin 13.9 g/dL, calcium 9.2 mg/dL, total protein 7.1 g/dL, and creatinine 1.0 mg/dL. Chest X-ray revealed multiple pulmonary nodules, which were confirmed on CT scan demonstrating bronchocentric distribution with findings concerning for diffuse idiopathic pulmonary neuroendocrine cell hyperplasia vs metastatic malignant lesions. CT of the abdomen and pelvis was normal without extrapulmonary lesions, PET scan did not reveal any hypermetabolic activity or other lesions concerning for malignancy. Bronchoscopic biopsy was nondiagnostic; however, subsequent CT-guided biopsy revealed amorphous material with multinucleated giant cells, negative for malignancy and Congo red staining. Stains for acid-fast bacilli and fungal organisms were negative. Mass spectrometry demonstrated lung parenchyma with mild lymphoplasmacytic proliferation surrounding amorphous eosinophilic material, consistent with kappa light chain deposition disease. She was eventually diagnosed with PLCDD and was recommended a hematologic workup for possible chemotherapy versus stem cell therapy. Discussion Most patients with LCDD present at an advanced stage due to its gradual onset and delayed diagnosis. Pulmonary or gastrointestinal involvement is rare. Our patient presented with bilateral pulmonary nodules that may be detected early on CT are often overlooked or mistaken for lung cancer. PLCDD and primary amyloidosis share similar pathogenesis and histologic features, including eosinophilic amorphous deposits positive for κ light chains. However, unlike amyloidosis, PLCDD deposits are granular, non-fibrillar, and lack apple-green birefringence under polarized light. Correlating high-resolution CT findings with the patient’s clinical history, examination, and laboratory data greatly refines the differential diagnosis of lung nodules. This abstract is funded by: None
Dwarakanath et al. (Fri,) studied this question.