A Rare Case of Immunotactoid Glomerulopathy Associated with Monoclonal Gammopathy of Renal Significance and Potential Multiorgan Involvement

Abstract

The term MGRS (Monoclonal Gammopathy of Renal Significance) is a newly recognized entity characterized by the renal deposition of a monoclonal protein. It arises in the context of hematologic disorders that do not meet the diagnostic criteria for plasma cell dyscrasias or lymphoma. Numerous disease entities fall under the MGRS category, each associated with a specific type of monoclonal protein that causes renal injury. This category also includes Immunotactoid Glomerulopathy (ITG), a rare glomerular disorder identified by the existence of immunoglobulin deposits in the glomeruli. These deposits have a substructural arrangement resembling microtubules with diameters ranging from 15 to 50 nm with a hollow center and organized in parallel arrays. Patients diagnosed with MGRS should undergo treatment targeting the clone producing the nephrotoxic monoclonal immunoglobulin. This is essential in preventing renal failure, as well as the progression to more advanced monoclonal gammopathies. We present the case of a 49-year-old female diagnosed with ITG associated with monoclonal gammopathy. The condition followed an indolent course for approximately 8 years before the diagnosis. At the time of presentation to the hematologist, she also exhibited a macular skin eruption and peripheral nerve impairment Except for the renal biopsy, other biopsies were not performed. However, during treatment and post-treatment, we observed an improvement and even the disappearance of cutaneous lesions, as well as a clinical improvement in neurological symptoms. These observations suggest a potential multiorgan involvement in the context of monoclonal gammopathy.