Lysosomal “mottled appearance”, or uneven electron-dense content related to monoclonal gammopathy (MG), has been mainly described in light chain proximal tubulopathy (LCPT). We aimed to determine the ultrastructural characteristics of lysosomal mottled appearance in kidney biopsies and its association with LCPT and MG. Seventy-seven biopsies were grouped into LCPT (n = 5), MG conditions other than LCPT (n = 43), and non-MG conditions (n = 29). The mottled lysosomes in the renal tubules were evaluated using transmission electron microscopy and morphometric analysis. Mottled lysosomes were more prevalent (% of present cases) and frequent (no. of mottled lysosomes/20,000× ultramicroscopic field) in the LCPT group (100% and 8.20 ± 4.15/field) than in the MG (41.9% and 1.13 ± 2.05/field) and non-MG (37.9% and 0.80 ± 1.44/field) groups. In morphometric analysis of all mottled lysosomes (n = 520) detected from the 34 biopsies (5 LCPT, 18 MG, and 11 non-MG), we found that mottled lysosomes were larger, more irregular, and more electron-dense for the LCPT group than for the MG and non-MG groups. Therefore, mottled lysosomes can be present in disorders other than LCPT or even without MG. The morphological characteristics of mottled lysosomes could provide objective guidance for the diagnosis of LCPT.

Relapsing polychondritis is a rare condition characterized by inflammation and subsequent degeneration of cartilages. Deformity of the pinna, nasal saddling and stridor due to involvement of the cartilages of the respiratory tract may lead to patients being referred to the otolaryngologist for initial assessment and further management. Recent observations have suggested that relapsing polychondritis may occur as a paraneoplastic phenomenon in cases of myelodysplasia. The case of a patient with relapsing polychondritis, myelodysplastic syndrome and a monoclonal gammopathy is presented. The authors highlight the apparent existence of this association and encourage otolaryngologists to consider such possible links when cases of relapsing polychondritis present to the outpatients department.