Subepithelial deposits with microspherular structures in membranous glomerulonephritis

ABSTRACT

Rare cases of membranous glomerulopathy (MGN) with subepithelial deposits consisting of microspherular structures identified by electron microscopy have been described in the literature as either MGN with spherules or podocyte infolding glomerulopathy (PIG). The paucity of available studies shows a strong association with underlying autoimmune disease. To further understand the significance of subepithelial microspherular deposits, we retrospectively identified native kidney biopsies from 10 patients diagnosed as MGN with subepithelial microspherular structures identified by ultrastructural examination at the University of Rochester Medical Center (URMC) during an 11-year period. The majority were Caucasian (80%) with a mean age of 51.3 (±12.9) years. 50% had an autoimmune disorder, of which 80% were SLE. Two SLE cases had concomitant rheumatoid arthritis and Sjogren’s syndrome. One additional case had antiphospholipid syndrome and showed lupus-like features on biopsy. 40% were idiopathic and negative for PLA2R, NELL1, and THSD7A. MGN with subepithelial microspherular structures is frequently associated with an underlying autoimmune disease. The majority are negative for markers of primary MGN (PLA2R, THSD7A, and NELL1) and show features suggestive of secondary MGN.

KEYWORDS:

• Membranous nephropathy
• systemic lupus erythematosus
• autoimmune disorder
• microspherules
• spherules
• podocyte infolding glomerulopathy (PIG)
• membranous glomerulopathy with spherules

Acknowledgments

The authors are grateful to Karen Vanderbilt, Tracy Fontaine-Matteson, Qi Yang, and Sierra Kovar for their excellent technical support, and special thanks to Dr. Arundathi Namassivaya and Dr. Manasvi Jaitly.

Author contributions

HYC designed the study and wrote the first draft of the manuscript. JJ and BG critically revised the work. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Statement of Ethics

This research was performed under approval of an institutional review board at URMC (STUDY00007001), and all ethical principles and guidelines for the protection of human subjects were followed.

Additional information

Funding

This research was supported by funding from the Department of Pathology and Laboratory Medicine at University of Rochester.