Imerslund-Grasbeck sydrome: the significance of the annular deposits or structures determined by electron microscopy

Abstract

Ayhan Ozcan, Yildirim Karslioglu, Yusuf Oguz, Mahmut Ilker Yilmaz, Emin Oztas

Objectives: Imerslund-Gräsbeck syndrome (IGS) with or without proteinuria is a rare autosomal recessive disorder seen in childhood and it is commonly resulting in megaloblastic anemia due to cobalamine deficiency. There are limited studies related to its electron microscopic features in addition to its light and immunofluorescence findings in kidney. Case report: A 19-year-old male who had taken vitamin B12 and folat due to IGS since 1-year-old was admitted nephrology service with flank pain. His blood pressure, routine blood chemistry, total protein, albumin, blood urea nitrogen (BUN) and cryoglobulin were normal. Total protein was 518 mg/24 h. Kidney biopsy was performed because of the persistent proteinuria. Light microscopy revealed minimal increase in mesangial cells and matrix. Immunoflourescence findings were unremarkable. Electron microscopy revealed irregular thickness and thinness in glomerular basement membrane (GBM) and cytoplasmic swelling in endothelial cells and podocytes. Widespread annular deposits or structures consisted with polyribosome were the most striking finding ultrastructurally. Discussion: Ultrastructural findings of IGS are unremarkable or small possible focal defects in GBM and mesangial proliferation may be found. The deposits or structures consisted with polyribosome and described in electron microscopy may misdiagnose as organized annular immune deposits. There are limited studies related to increases of these structures in patients with vitamin B12 supplement therapy. This report aimed to pay attention to the possibility of confuse with organized annular immune deposits of these electron microscopic deposits in a rare syndrome