Immunotactoid glomerulopathy leading to the discovery of POEMS syndrome


Monoclonal gammopathy of renal significance (MGRS) can manifest in many different ways depending on the nature of the immunoglobulin and its physicochemical properties. MGRS can lead to the discovery of a hematological malignancy. We report the case of a 32-year-old female patient who underwent renal biopsy on account of an impure nephrotic syndrome associated with immunoglobulin (Ig)G κ monoclonal gammopathy. Histological analysis revealed membranoproliferative glomerulonephritis with IgG, IgM, κ, λ, and C3 deposits. Due to an unfavorable progression, a second renal biopsy was performed. Electron microscopy analysis revealed an immunotactoid glomerulopathy. At the same time, a POEMS syndrome diagnosis (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin abnormalities) was confirmed in light of the following: 1) IgG κ monoclonal gammopathy, 2) axonal neuropathy, 3) osteosclerosis, 4) melanoderma, 5) hepatosplenomegaly and adenopathies, 6) Castleman disease, and 7) edema. Our observation is the first case of immunotactoid glomerulopathy leading to the discovery of a POEMS syndrome. Renal involvement in POEMS syndrome typically exhibits a thrombotic microangiopathy-like membranoproliferative glomerulonephritis appearance associated with endothelial lesions stigmata. However, monoclonal immunoglobulin deposition disorder should be considered in the event of an atypical case. In this indication, electron microscopy is the examination of choice for assessing immunoglobulin deposition nephropathy.
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