Presumed Paravertebral Inflammatory Pseudotumor in Relapsing Granulomatosis With Polyangiitis: Fluorodeoxyglucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT) Findings and Complete Metabolic Response to Rituximab-Based Therapy
- 1Radiology, Erasmus Hospital, Bruxelles, BEL
- 2Nuclear Medicine, Erasmus Hospital, Bruxelles, BEL
Abstract
We report a case of a 60-year-old woman with biopsy-proven, proteinase-3 (PR3)-antineutrophil cytoplasmic antibody (ANCA)-associated granulomatosis with polyangiitis (GPA), diagnosed six years earlier, who presented with right lower thoracic pain during a disease relapse. The relapse was supported by serological reactivation with a markedly elevated anti-PR3 level, a raised erythrocyte sedimentation rate (ESR) (88 mm/h), and elevated C-reactive protein (CRP) (48 mg/L). Unenhanced computed tomography (CT) showed no pulmonary parenchymal abnormality but revealed soft-tissue infiltration of the anterior and right lateral paravertebral mediastinal fat extending from T4-T5 to T10-T11, without adjacent osseous involvement. Fluorine-18 (18F)-fluorodeoxyglucose (FDG) positron emission tomography/CT (PET/CT) demonstrated intense uptake within the lesion, with a maximum standardized uptake value (SUVmax) of 12.06. Given the differential diagnoses of lymphoma and other granulomatous disease, the lesion was interpreted as a presumed GPA-related paravertebral inflammatory pseudotumor; it was not biopsied. After rituximab and methylprednisolone, the patient achieved complete clinical and biological remission with ANCA seroconversion, and follow-up FDG PET/CT at three months showed complete resolution of the abnormal uptake. Because neither FDG avidity nor treatment response was specific, the presumed diagnosis could not be confirmed histologically in this case.
Related
- When Eosinophilic Granulomatosis With Polyangiitis (EGPA) Looks Like Granulomatosis With Polyangiitis (GPA): Navigating a Complex Case of Anti-neutrophil Cytoplasmic Antibodies (ANCA) Vasculitis
- Necrotizing Myositis as a Rare Presenting Manifestation of Childhood-Onset Granulomatosis With Polyangiitis: A Case Report.
- Prostatic Involvement in Granulomatosis with Polyangiitis: A Case Report and Scoping Review
- Isolated necrotizing scleritis revealing silent pulmonary granulomatosis with polyangiitis : A case report of rare diagnostic clue
- Rapidly Progressing Interstitial Fibrosis and Glomerulonephritis due to Granulomatosis With Polyangiitis Presenting With Calf Pain
BibTeX
@article{khloufi2026presumed,
title = {{Presumed Paravertebral Inflammatory Pseudotumor in Relapsing Granulomatosis With Polyangiitis: Fluorodeoxyglucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT) Findings and Complete Metabolic Response to Rituximab-Based Therapy}},
author = {Yasmina Hamida El Khloufi and Redouane Soussi and Pascale Bohy},
journal = {Cureus},
year = {2026},
month = oct,
doi = {10.7759/cureus.117516},
url = {https://doi.org/10.7759/cureus.117516},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Presumed Paravertebral Inflammatory Pseudotumor in Relapsing Granulomatosis With Polyangiitis: Fluorodeoxyglucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT) Findings and Complete Metabolic Response to Rituximab-Based Therapy
AU - Yasmina Hamida El Khloufi
AU - Redouane Soussi
AU - Pascale Bohy
PY - 2026
DA - 2026/10/05
JO - Cureus
DO - 10.7759/cureus.117516
UR - https://doi.org/10.7759/cureus.117516
AB - We report a case of a 60-year-old woman with biopsy-proven, proteinase-3 (PR3)-antineutrophil cytoplasmic antibody (ANCA)-associated granulomatosis with polyangiitis (GPA), diagnosed six years earlier, who presented with right lower thoracic pain during a disease relapse. The relapse was supported by serological reactivation with a markedly elevated anti-PR3 level, a raised erythrocyte sedimentation rate (ESR) (88 mm/h), and elevated C-reactive protein (CRP) (48 mg/L). Unenhanced computed tomography (CT) showed no pulmonary parenchymal abnormality but revealed soft-tissue infiltration of the anterior and right lateral paravertebral mediastinal fat extending from T4-T5 to T10-T11, without adjacent osseous involvement. Fluorine-18 (18F)-fluorodeoxyglucose (FDG) positron emission tomography/CT (PET/CT) demonstrated intense uptake within the lesion, with a maximum standardized uptake value (SUVmax) of 12.06. Given the differential diagnoses of lymphoma and other granulomatous disease, the lesion was interpreted as a presumed GPA-related paravertebral inflammatory pseudotumor; it was not biopsied. After rituximab and methylprednisolone, the patient achieved complete clinical and biological remission with ANCA seroconversion, and follow-up FDG PET/CT at three months showed complete resolution of the abnormal uptake. Because neither FDG avidity nor treatment response was specific, the presumed diagnosis could not be confirmed histologically in this case.
SN - 2168-8184
ER -