The Clinicopathologic Significance of Endothelial Tubuloreticular Inclusions in Glomerular Diseases

Abstract

Background: The presence of tubuloreticular inclusions (TRIs) in endothelial cells (ECs) always evokes suspicion of an association with underlying viral infections or autoimmune diseases. However, other underlying diseases can be associated with TRI expression. Since identification of the underlying disease is of primary consideration for management of glomerulonephritis (GN), it is important to clarify the clinical significance of TRI expression.Methods: The authors studied 104 renal biopsy cases having TRI. They investigated their clinicopathological profiles and focused on potential connections with underlying diseases.Results: Among 104 renal biopsy cases, 62 cases (59.6%) were associated with lupus nephritis (LN) and 20 cases (19.2%) were associated with a viral infection (hepatitis B virus (13), hepatits C virus (4), and human immunodeficiency virus (3)). Other underlying disease groups included membranous GN (MGN) (7), IgA nephropathy (7), Henoch-Schoenlein purpura (HSP) nephritis (2), and others (6). The incidence of TRIs in both LN and viral infections was significantly higher than for other diseases (p < 0.0001). Among 7 MGN cases, 2 cases were diabetes, 1 case was associated with lung cancer, another case with antineutrophilic cytoplasmic antibody (ANCA), and the others showed no evidence of systemic disease. On immunofluorescence (IF) study, 2 MGN cases, 2 IgA nephropathy cases, and 1 HSP nephritis case showed C1q deposition, with no evidence of SLE.Conclusions: TRIs were identified in MGN and other glomerular diseases, including IgA nephropathy and HSP nephritis. However, a diagnosis of LN should be considered because TRIs associated with a full-house IF pattern are usually found in LN.