SHM Converge Scientific Abstract ePoster Gallery-Widespread Recurrence of Igg4-Related Disease: A Rare Lymphoma Mimic

Pdf Summary

This case describes a 68-year-old man with a history of IgG4-related autoimmune pancreatitis who presented with generalized weakness, significant weight loss, thrombocytopenia, and acute kidney injury. CT and FDG-PET/CT showed widespread FDG-avid lymphadenopathy above and below the diaphragm, splenomegaly, and lung base uptake, strongly suggesting lymphoma. Initial hematologic testing also revealed biclonal gammopathy, further increasing concern for a lymphoproliferative disorder.<br /><br />However, tissue diagnosis clarified the picture. Lymph node biopsy ruled out hematologic malignancy and showed IgG4-positive plasma cells. Bone marrow biopsy found only a minute monoclonal B-cell population consistent with MGUS. Most importantly, kidney biopsy demonstrated IgG4-rich plasma cells with storiform fibrosis, confirming relapse of IgG4-related disease with IgG4-related tubulointerstitial nephritis.<br /><br />The patient was treated with rituximab and steroids, leading to rapid improvement in kidney function and near resolution of lymphadenopathy on follow-up PET/CT three months later. The report emphasizes that IgG4-RD is a multi-organ autoimmune fibroinflammatory condition that can closely mimic lymphoma on imaging, especially when disease is widespread. Diagnosis may be delayed by anchoring bias and incomplete documentation of prior IgG4-RD in the electronic health record.<br /><br />Key take-home points are that IgG4-RD should remain in the differential for diffuse FDG-avid lymphadenopathy, relapse is common—approaching 40%—and clear documentation of prior IgG4-RD is important to guide future clinicians.

Asset Subtitle

Allison A. Reinhardt

Meta Tag

Author List Allison A. Reinhardt, Bibek Saha, Katlin Schmitz, Nickolas Steinauer, Ray Qian

Category Clinical Vignettes

Concept IgG4-Related Disease

Concept Tissue Biopsy

Concept Immunohistochemistry

Concept PET-CT

Concept IgG4-Positive Plasma Cells

Distinguished Non-Finalist

Presenter Organization Mayo Clinic

Presenting Author Allison A. Reinhardt

Track Adult

Keywords

IgG4-related disease

autoimmune pancreatitis

FDG-avid lymphadenopathy

lymphoma mimic

tubulointerstitial nephritis

rituximab

storiform fibrosis

biclonal gammopathy

acute kidney injury

splenomegaly

IgG4-Related Disease

Tissue Biopsy

Immunohistochemistry

PET-CT

IgG4-Positive Plasma Cells