Abstract
A 30-year-old woman on steroid therapy for eosinophilia presented with nephrotic syndrome during steroid tapering. She was diagnosed with membranous nephropathy (MN) stage II–III (positive for IgG1 and IgG4) by renal biopsy. There was no evidence of secondary MN. Her urinary protein level was controlled to 0.5 g/day or less, and her eosinophil count in white blood cell differential was stabilized at less than 10% without increasing the steroid dosage. The renal specimen did not show any enhanced granular expression of PLA2R along the glomerular basement membrane, and PLA2R was not detected in the patient’s serum. On retrospective analysis, enhanced granular staining for thrombospondin type-1 domain-containing 7A (THSD7A) in the glomeruli was detected in the biopsy, and anti-THSD7A IgG was detected in the serum using a commercial indirect immunofluorescence test (IFT). Based on these, the case was considered as THSD7A-associated MN with comorbid eosinophilia. The causal relationship between THSD7A-related MN and eosinophilia was unclear. However, a few cases of THSD7A-associated MN with eosinophilia have been reported, and further clarification on the relationship between THSD7A-related MN and eosinophilia is warranted.
Highlights
Membranous nephropathy (MN), a common nephrotic syndrome in adults, is caused by immune complex deposition in the subepithelial area of the glomerular basement membrane and the subsequent activation of the complement system
Autoantibodies against podocyte antigen, thrombospondin type-1 domain-containing 7A (THSD7A), have been reported to be responsible for primary MN; but, it remains uncertain how these antigens are recognized by the immune system
WBC and eosinophil count increased at the same time as reactive arthritis, so it cannot be denied that reactive arthritis caused the eosinophil increase [11]
Summary
Membranous nephropathy (MN), a common nephrotic syndrome in adults, is caused by immune complex deposition in the subepithelial area of the glomerular basement membrane and the subsequent activation of the complement system. A 30-year-old woman, in March X-1 year, after wisdom tooth extraction, manifested bilateral arthralgia, swelling of lower legs and forearms, and pain on Achilles tendon sticking area She visited a primary care clinic, where her blood test showed an increase in WBC count and was referred to a city hospital. She was diagnosed with eosinophilia and was transferred to the rheumatology clinic in our institute at the end of March X-1 year At that time, her blood and urine examinations showed the following: WBC, 15,400/μL; eosinophils, 4774/ μL (31%); serum IgE, 530 IU/mL; urine protein, 3+; and urine occult blood, 1+. We retrospectively identified the heavier band detected by western blotting as THSD7A, which was supported by the following findings: enhanced granular staining for THSD7A in the glomeruli in a biopsy specimen (Fig. 5b), and detection of anti-THSD7A IgG in the serum using a commercial indirect IFT (Fig. 6b). We diagnosed this case as THSD7A-associated MN
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