Nodular pulmonary light chain deposition disease: an entity associated with Sjogren syndrome or marginal zone lymphoma

Background Light chain deposition disease (LCDD) is usually a systemic disorder characterised by non-amyloid monoclonal immunoglobulin light chain deposition in tissues. Localised nodular pulmonary (NP) LCDD is a rare and poorly characterised entity and, owing to the difficulties in diagnosis, limited data are available. Methods We investigated the clinical, radiological and pathological characteristics of a series of six confidently diagnosed cases of NPLCDD. Results There were three men and three women with ages ranging from 33 to 74 years. In all cases there were single or multiple pulmonary nodules, in one case associated with cysts. Two patients had no previous history of a lymphoproliferative or autoimmune disorder, two had Sjogren syndrome (SS) and two had extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). Lung biopsies led to diagnoses of MALT lymphoma in four patients, including both of those with a previous history of lymphoma and one with SS. In five cases the diagnosis was confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and in one by electron microscopy. There was no evidence of systemic LCDD in any of the cases. Five patients had an indolent course in spite of limited therapeutic intervention while, in the patient who died, the cause of death was related to the spread of the lymphoma and was not due to the pulmonary lesions. Conclusions NPLCDD is an indolent disease, in most cases associated with MALT lymphoma or autoimmune disease.