Extraglomerular immune complex deposition in lupus nephritis

Background Lupus nephritis (LN) is a common manifestation and a major cause of morbidity and mortality in systemic lupus erythematosus (SLE) patients. It is characterized by glomerular and often extraglomerular immune complex deposition. Purpose Given the emerging importance of the tubulointerstitial compartment, we conducted a retrospective study of 78 LN biopsies to enumerate the spectrum of extraglomerular immune complex deposition that can be observed in lupus nephritis by electron microscopy and to identify possible clinical or pathologic correlates. Results The presence of tubulointerstitial immune complex deposition often accompanied interstitial inflammation, but some discrepancies were also seen. Conclusions As target antigens are identified, correlation with glomerular, tubulointerstitial, and vascular immune complex deposition will be of increasing interest.

Diffuse Subamniotic Calcification: A Novel Pattern of Placental Calcification

Two primary patterns of placental calcification have been described, each with distinctive pathophysiology and clinical relevance. We report a novel pattern of diffuse subamniotic calcification. It occurred in a 25-week placenta involved by recurrent chronic histiocytic intervillositis (CHI) associated with severe intrauterine growth restriction (IUGR) and intrauterine fetal demise (IUFD). This was the mother’s third stillbirth related to CHI, despite treatment with intravenous immunoglobulin (IVIG), prednisone, low-molecular-weight heparin, and acetylsalicylic acid (ASA). On placental examination, the majority of the fetal surface was calcified. This variably formed a continuous band or dispersed calcium microparticles. Electron microscopy demonstrated associated electron dense deposits highly suggestive of immune complex deposition. CHI explains recurrent IUGR and stillbirth, but has not been associated with calcification or immune complex deposition. We hypothesize IVIG therapy may have caused immune complex deposition and subsequent dystrophic calcification, supported by its rare association with immune complex deposition disorders in the kidney. Identification of additional cases with this pattern of calcification, with additional studies on fresh tissue including immunofluorescence, electron microscopy and mass spectrometry, may aid in elucidating the underlying pathophysiology and clinical significance of this unusual lesion.

Resolution of Q Fever–Associated Cryoglobulinemia With Anti-CD20 Monoclonal Antibody Treatment

Immunologic phenomena can complicate chronic infections with Coxiella burnetii (Q fever), including immune complex deposition causing vasculitis, neuropathy, and glomerulonephritis. We describe the case of a man with Q fever endocarditis, mixed cryoglobulinemia, and life-threatening vasculitis driven by immune complex deposition who was successfully treated with B cell depleting therapy (rituximab).