Heavy chain deposition disease in kidney biopsies Alenka Vizjak, Jerica Mraz, Jelka Lindič, Dušan Ferluga Institute of Pathology, Faculty of Medicine University of Ljubljana, Slovenia Disclosures: no conflicts of interest
Heavy chain deposition disease (HCDD) • HCDD - a rare monoclonal immunoglobulin-related disorder of not yet fully explored pathogenesis • Characterized by production and systemic deposition of structurally abnormal immunoglobulin heavy chains, while light chains absent in the deposits • First described by Aucouturier et al(N Engl J Med 1993; 329: 1389-93)
Patients and methods • 4 biopsy cases of HCDD (5 kidney biopsies; 1 autopsy), representing 0.09% prevalence among 5481 native kidney biopsies • All 4 female patients, age range 62 – 79 yrs, mean age 73.0 yrs • Standard light microscopy • Immunofluorescence microscopy IgA, IgG, IgM, κ, λ, C3, C1q, fibrin/fibrinogen, albuminIgG1, IgG2, IgG3, IgG4, γCH1, γCH2, γCH3 • Electron microscopy
Clinical presentation / diagnosis in 4 patients with HCDD CKD – chronic kidney disease, NS – nephrotic syndrome
Light and electron microscopy in 4 cases with HCDD Light microscopy • Diffuse nodular glomerulosclerosis 4/4 • Glomerular capillary aneurysms 4/4 • Mesangial proliferation, 4/4with segm endo-, membranoprol pattern 3/4 • Extracapillary crescents (few) 2/4 Electron microscopy • Punctate and powdery electron dense deposits 3/4
Conclusions of our study • Immunofluorescence examination of kidney biopsy, including testing for Igs heavy and light chains, as well as IgG subclasses, is crucial for the diagnosis of HCDD. • Our study showed that HCDD is peculiar among MIDD because of uniform pattern of nodular glomerulosclerosis with pronounced capillary aneurysms and significant proliferation due to complement activation. • Constant deletion of the gamma heavy chain CH1 domain and its significance in the pathogenesis of HCDD was confirmed.