电子致密物沉积病的超微结构观察

电子致密物沉积病（dense deposit disease,DDD）是一种罕见的肾小球慢性疾病。本文对5例DDD的超微结构进行观察，并结合临床及HE、染色（PAS、PASM－Masson）、免疫组化（IgG、IgM、IgA、C3、C1q、HBsAg、HBcAg）结果进行分析。结果显示：DDD的临床表现及组织形态学均具有多样性。5例中临床表现2例为肾病综合症，2例为慢性肾炎综合征，1例为急性肾功不全。形态学改变3例为膜增殖性肾小球肾炎（MPGN），1例系膜增生伴局灶节段膜增殖（MePGN伴sMPGN），1例弥漫系膜增生性肾小球肾炎（MePGN）。电镜下肾小球基底膜弥漫性增厚，层内见条带状高电子致密物沉积，其中1例伴有内皮下和上皮下沉积物，4例系膜区块状沉积物。免疫组化提示毛细血管袢以C3、IgM沉积为主，系膜区C3沉积，1例乙型肝炎标志物阳性。DDD的发生可能与补体C3的激活并沉积及免疫复合物机制有关，其超微结构的特征性改变对该病的诊断与鉴别诊断具有重要价值。

Ultrastructural observation of dense deposit disease

Dense deposit disease (DDD) is a rare form of chronic glomerulonephritis. 5 cases of DDD were examined with electron microscope and analyzed in conjunction with its clinical features, HE and special staining (PAS,PASM-Masson), and immunohistochemical (IgG,IgM, IgA,C3,C1q,HBsAg,HBcAg)observations.The clinical manifestation and histologic morphology of DDD were variable. Two of five patients showed nephrotic syndrome, the other two patients showed chronic nephritic syndrome, and one patient showed acute renal insufficiency. With light microscopy, 3 cases showed membranoproliferative glomerulonephritis (MPGN), 1 case showed mesangial proliferative glomerulonephritis with segmental membranoproliferative glomerulonephritis (MePGN+sMPGN), and 1 case showed diffuse mesangial proliferative glomerulonephritis (MePGM). Ultrastructural examination revealed capillary walls were irregularly thickened and very electron-dense ribbon-like deposited within the glomerular capillary basement membranes. Subendothelial and transmembranous deposits was found in 1 case and nodular dense deposits of mesangial zones were found in 4 cases. Immunohistochemical studies indicated linear deposits of C3 and IgM along capillary walls and deposits of C3 in the mesangium. Hepatitis B markers were seen in the glomeruli. Incidence of DDD may be related to an activation of C3 complement and to the possible role of an immune complex mechanism. The ultrastructural characteristic change of DDD has an important value in its diagnosis and its classification.