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Abstract: TH-PO698

A Case of Coexisting Primary Membranous Nephropathy and Dermatomyositis

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Mistry, Kavita, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Lecker, Stewart H., Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
Introduction

Dermatomyositis (DM) is an inflammatory disorder of the skin and skeletal muscle characterized by cutaneous eruptions and myositis. DM is associated with malignancy, interstitial lung disease, esophageal dysmotility and cardiac complications. Unlike other connective tissue diseases, DM does not classically feature renal involvement, although several small case series and retrospective analyses have described a small minority of patients with DM who develop renal pathologies, including ATN in the setting of rhabdomyolysis as well as various glomerular diseases.

Case Description

A 56-year-old African American woman presented with one week of leg swelling. Vital signs were remarkable for hypertension to systolic BPs of 170s, and exam was remarkable for prominent facial edema and 3+ bilateral lower extremity edema, with skin hyperpigmentation on the face, neck, chest and upper arms. Creatinine was at her baseline of 0.7 mg/dL. U/A revealed 4+ blood and 4+ protein, quantified at 10.2 g/g. Urine microscopy revealed lipid casts and <1 isomorphic RBC/hpf. Nephrology and rheumatology were consulted and recommended workup as follows: C3 and C4 normal, SPEP negative, serum anti-PLA2R IgG negative, HIV and hepatitis B/C serologies negative, ANA positive 1:1280 nuclear fine speckled pattern. She had negative dsDNA, anti-Sm, centromere B, RNP, anti-SCL 70, anti-SS-A, anti-SS-B, anti-cardiolipin and anti-B2 glycoprotein antibodies. CPK was sent on account of 4+ blood on U/A with relative paucity of RBC on microscopy and was elevated at 1249 IU/L. Myositis panel was sent and returned positive for anti-MI2 alpha and beta antibodies, consistent with DM. A renal biopsy was performed and revealed membranous nephropathy (MN). Although serum anti-PLA2R IgG was negative, the biopsy stained positive for anti-PLA2R IgG, suggesting primary MN. Comprehensive malignancy evaluation was performed given the close association of both membranous nephropathy and dermatomyositis with cancers and was negative. The patient was started on rituximab for management of MN and prednisone for management of DM.

Discussion

To our knowledge, this is the third case report describing coexisting primary MN and DM in the absence of underlying malignancy. The biological basis for the coexistence of these two pathologies in a single patient remains to be elucidated, although can be presumed to result from a breakdown of immune tolerance.