[A rare manifestation of a cystic lung disease with high suspicion of pulmonary light chain deposition disease (LCDD)].

This case report describes a rare form of cystic lung disease, strongly suspected to be a pulmonary manifestation of light chain deposition disease (LCDD). Pulmonary light chain deposition disease (PLCDD) is an uncommon form of cystic lung disease, presenting with extensive bilateral cysts and nodules. Definitive diagnosis requires histopathological confirmation, although this may not always be feasible in cases of respiratory compromise. The diagnosis of LCDD should be considered when the clinical findings are atypical for other cystic lung diseases, the HRCT morphology suggests nodular-cystic amyloidosis (HRCT with cysts and nodules, nodules also involving the walls of the cysts, predominantly located in the periphery of the lower lung areas) or when monoclonal free light chains, particularly kappa chains, are detected in serum and/or urine.