Light chain deposition disease involving the airways: diagnosis by fibreoptic bronchoscopy.

Light chain deposition disease (LCDD) infrequently affects the lungs and usually causes damage to the parenchyma, while bronchial involvement appears to be very rare. The present authors report the case of a 64-yr-old female with LCDD characterised by asymptomatic airway involvement. Ten months after excision of a poorly differentiated vaginal carcinoma, a routine chest computed tomography (CT) scan revealed two lung cysts, several bilateral nodules and diffuse bronchial thickening. Pulmonary function tests were normal. Fibreoptic bronchoscopy showed marked diffuse mucosal thickening with highly conspicuous vascular plexuses. Nonamyloidal deposits were found in the bronchial wall, but no definite diagnosis could be proposed. On follow-up, the patient was still asymptomatic and the CT scan and endoscopic appearance remained unchanged. The final diagnosis of kappa LCDD was established 18 months later by another series of bronchial biopsies with frozen samples. Interestingly, electron microscopy showed dense granular deposits associated with nonamyloidal fibrils. An increased number of lung cysts were observed 32 months after identification of bronchial abnormalities, confirming the progressive nature of the disease. No extrapulmonary deposits or immunoproliferative disorder were found. In conclusion, light chain deposition disease, which may remain latent for several years, can entirely involve large airways and may be diagnosed by bronchial biopsy.