FDG Uptake in a Rheumatoid Nodule With Imaging Appearance Similar to a Malignant Soft Tissue Tumor

Hyoepiglottic Rheumatoid Nodule Mimicking Head and Neck Malignancy on 18 F-FDG PET/CT

ABSTRACT

A 54-year-old man with a history of tonsillar squamous cell carcinoma treated with chemoradiotherapy and an 18-year history of seropositive rheumatoid arthritis in remission without maintenance therapy presented with right cervical pain and dysphagia for several months. Flexible laryngoscopy did not show any lesion, and MRI revealed a necrotic lesion inside the thyro-hyo-epiglottic space attached to the hyoid bone. 18 F-FDG PET/CT demonstrated a moderately increased metabolic activity of the lesion without any other suspected lesions. Surgical resection was performed, and pathology revealed a necrotizing granuloma compatible with a rheumatoid nodule.

Methotrexate-related lymphoproliferative disorder of the stomach in a patient with rheumatoid arthritis: a case of disease regression after methotrexate cessation

We report the case of a 78-year-old woman with methotrexate-related gastric lymphoproliferative disorder (LPD). The patient had a history of rheumatoid arthritis (RA) and had been treated with methotrexate (MTX). Endoscopic examination revealed round elevated lesions in the stomach, and a biopsy specimen showed atypical lymphoid cell proliferation. Immunohistological study found these atypical cells to be positive for L-26 but not for CD3 or EBER. Therefore, we made a diagnosis of MTX-related LPD showing features of diffuse large B-cell lymphoma. Combined positron emission tomography-computed tomography (PET-CT) using 18F-fluorodeoxyglucose (FDG) showed increased avidity in the stomach in addition to slightly increased FDG-avidity in the mediastinum and left chest wall. We decided not to start chemotherapy but to discontinue administration of MTX, with follow-up using endoscopy and PET-CT. The endoscopic examinations after cessation of MTX demonstrated gradual regression of the elevated lesions. PET-CT 6 months after cessation showed no increased FDG avidity in the stomach. While disease regression was observed in the stomach, the other FDG-avid spots remained unchanged on PET-CT. Therefore, we performed chemotherapy as additional therapy. On PET-CT after chemotherapy, the FDG-avid spots remained unchanged for more than 1 year, and we eventually concluded that they were RA-related inflammatory lesions. In patients with MTX-related LPD, cessation of MTX may be a therapeutic option, but careful follow-up and chemotherapy in accordance with the clinical course are essential.

The pivotal role of FDG-PET/CT in modern medicine

The technology behind positron emission tomography (PET) and the most widely used tracer, 2-deoxy-2-[18F]fluoro-D-glucose (FDG), were both conceived in the 1970s, but the latest decade has witnessed a rapid emergence of FDG-PET as an effective imaging technique. This is not least due to the emergence of hybrid scanners combining PET with computed tomography (PET/CT). Molecular imaging has enormous potential for advancing biological research and patient care, and FDG-PET/CT is currently the most widely used technology in this domain. In this review, we discuss contemporary applications of FDG-PET and FDG-PET/CT as well as novel developments in quantification and potential future indications including the emerging new modality PET/magnetic resonance imaging.

Role of (18)F-FDG PET Scan in Rheumatoid Lung Nodule: Case Report and Review of the Literature

Flourine-18 fluoro-2-deoxy-glucose (¹⁸F-FDG) positron emission tomography combined with computed tomography (PET/CT) is a useful test for the management of malignant conditions. Inflammatory and infectious processes, however, can cause increased uptake on PET scanning, often causing diagnostic dilemmas. This knowledge is important to the rheumatologist not only because of the inflammatory conditions we treat but also because certain rheumatic diseases impose an increased risk of malignancy either due to the disease itself or as a consequence of medications used to treat the rheumatic diseases. There is an increasing body of evidence investigating the role of PET scans in inflammatory conditions. This paper describes a patient with rheumatoid arthritis who developed pulmonary nodules that showed increased uptake on PET/CT scan and reviews the use of PET scanning in the diagnosis and management of rheumatoid arthritis.

Fluorodeoxyglucose (FDG) uptake in pulmonary rheumatoid nodules diagnosed by video-assisted thoracic surgery lung biopsy: two case reports and a review of the literature

Two cases of rheumatoid nodules evaluated by fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and video-assisted thoracic surgery (VATS) biopsy are reported. The first case was that of a 44-year-old woman who presented with a cavitated nodule with intense standardized uptake values (SUVs) both in the early (max 3.4) and delayed (max 4.4) phases, suggesting malignancy. However, after VATS biopsy, she was diagnosed as having a rheumatoid nodule with vasculitis. The second case was that of a 74-year-old woman admitted with bilateral lung nodules, two of which showed intense early (max 2.2) and delayed (max 6.0) phase SUVs, and mild early (max 0.6) and delayed (max 0.9) phase SUVs. These two nodules were finally proven to be a lung cancer and rheumatoid nodule without vasculitis, respectively. These cases show that rheumatoid nodules with an enhanced inflammatory process, such as vasculitis, can appear false-positive for malignancy on FDG-PET/CT scan images.