Clinicopathological and ultrastructural characterization of lipoprotein glomerulopathy: a study of six cases

To analyze the clinicopathological and ultrastructural features of lipoprotein glomerulopathy (LPG) in six biopsy-proven cases, with particular attention to the diagnostic value of electron microscopy.

Clinical data from six patients with biopsy-proven LPG were retrospectively analyzed, including sex, age, proteinuria, triglycerides, low-density lipoprotein, apolipoproteins, and lactate dehydrogenase. Pathological specimens were examined by light microscopy (HE, PAS, and PAM-Masson staining), immunohistochemistry (IgG, IgM, IgA, C3d, C4d, fibrinogen, ApoE, etc.), and transmission electron microscopy to systematically evaluate renal pathological changes. A comparative analysis was also performed with reference to the literature.

All six patients met the diagnostic criteria for nephrotic syndrome, presenting with proteinuria and hypertriglyceridemia. Characteristic pathological findings of LPG included diffuse dilation of glomerular capillary lumina containing abundant eosinophilic foamy material (6/6); strong positive expression of apolipoprotein E (ApoE) on immunohistochemistry (6/6); and ultrastructural confirmation of abundant lipid vacuoles, electron-dense granules, and lamellated proteinaceous thrombi within the capillary lumina. During follow-up (24-92 months), none of the three patients who received lipid-lowering therapy showed significant disease progression.

LPG is characterized by distinctive "foamy capillary" pathological changes and specific ApoE expression. The coexistence of lipid vacuoles and granular material on electron microscopy may serve as an important diagnostic criterion.