Abstract: SA-PO0968
IgG4-Related Tubulointerstitial Nephritis with Negative Contrast-Enhanced CT: Diagnostic Usefulness of Fluorodeoxyglucose-18-Positron Emission Tomography/CT
Session Information
- Pathology: Updates and Insights
November 08, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1800 Pathology and Lab Medicine
Authors
- Tanaka, Rina, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan
- Hara, Satoshi, Kanazawa Daigaku, Kanazawa, Ishikawa Prefecture, Japan
- Ikeda, Mari, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan
- Ohara, Mamiko, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan
- Suzuki, Tomo, Kameda Medical Center, Kamogawa, Chiba Prefecture, Japan
Introduction
Contrast-enhanced CT is typically useful in diagnosing IgG4-related kidney disease as it often reveals multiple low- density lesions or masses in the kidneys. We describe IgG4-related kidney disease detected by fludeoxyglucose-18 (FDG) positron emission tomography (PET)/computed tomography (CT) without detectable lesions on contrast-enhanced CT.
Case Description
A 68-year-old Japanese man presented with anemia and swollen para-aortic lymph nodes. Laboratory studies revealed a hemoglobin level of 10.7 g/dl, white blood cell count of 5900/ l, and platelet count of 446000/ l. No blasts were observed. Kidney function was preserved, with eGFR 63 ml/min per 1.73 m２. His IgG level was elevated at 3170 mg/dl, whereas other immunoglobulin levels were normal. A markedly high serum IgG4 level (>500 mg/dl) was observed. Serum complement levels were decreased with a C3c of 65 mg/dl and C4 of 8.8 mg/dl. The serum C-reactive protein level was 0.40 mg/dl, and the soluble interleukin-2 receptor level was increased at 1469 U/ml. Given the presence of lymphadenopathy and systemic involvement, malignant lymphoma was suspected. Therefore, FDG- PET/CT was performed and FDG uptake was observed in multiple lymph nodes, the spleen, and bone. Both kidneys were enlarged with high FDG uptake (standardized uptake value maximum = 6.69) . On the other hand, contrast-enhanced CT showed no low-density lesions in either kidney . Kidney biopsy revealed dense interstitial plasma lymphocytic infiltration with storiform fibrosis and IgG4-positive cells, confirming IgG4-related tubulointerstitial nephritis.
Discussion
IgG4-related renal disease can usually be detected by contrast-enhanced CT with low- density lesions or masses in the kidney, and there are few reports in which lesions are not detected by contrast-enhanced CT. This case suggests that FDG-PET/CT may be more sensitive than contrast-enhanced CT in detecting early-stage IgG4-related kidney disease with preserved kidney function.