Adult Presentation of Cutaneous Langerhans Cell Histiocytosis: 18 F-FDG PET/CT Detection of Systemic Disease.

ABSTRACT: Langerhans cell histiocytosis (LCH) is a rare hematological disease, more common in pediatric populations. A 26-year-old man with biopsy-proven cutaneous LCH underwent 18 F-FDG PET/CT systemic staging. 18 F-FDG PET/CT highlighted multiple sites of avid cutaneous disease within the natal cleft. Additional characteristic cystic lung disease was seen on the CT component and focal uptake in the pituitary stalk/hypothalamic region noted, a common but occult site of disease in this patient. Because of the rarity of adult-onset cutaneous LCH, guidance on management and staging is lacking. 18 F-FDG PET/CT is critical to baseline evaluation of systemic disease, as illustrated here.

Diffuse peritoneal carcinomatosis and Sister Mary Joseph nodule in ovarian carcinoma - exquisite demonstration of the peritoneal reflections on [18F]FDG PET/CT.

A case involving a 64-year-old woman with ovarian carcinoma on maintenance therapy who underwent 18-fluorodeoxyglucose positron emission tomography with computed tomography ([18F]FDG PET/CT) restaging due to rapid cancer antigen 125 (Ca-125) rise. This revealed recurrent disease within the pelvis and large volume, peritoneal carcinomatosis including an avid umbilical deposit, consistent with the rarely seen Sister Mary Joseph nodule (SMJN). This case elegantly demonstrates not only the anatomy of the peritoneal surfaces through avid disease deposition but also highlights the sensitive depiction of disease burden in peritoneal carcinomatosis, including the detection of rare manifestations such as SMJN.

Multimodality Appearances of Marginal Zone Lymphoma Masquerading as Cryptogenic Organizing Pneumonia-serial Chest Radiograph and High-resolution Computed Tomography Appearances: (18F) Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Staging Utility.

Marginal zone lymphoma (MZL) is a group of low-grade, indolent, non-Hodgkin lymphomas rarely manifesting in the lungs. A 46-year-old man presenting with shortness of breath and cough was investigated and treated over 10 months for an atypical pattern of lung disease in keeping with cryptogenic organizing pneumonia (COP). Initial lung biopsies were nondiagnostic - repeat sampling eventually showed MZL. Staging whole-body (18F) fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) demonstrated multisystem stage IV disease with intensely avid widespread pulmonary changes resembling COP. The case elegantly illustrates that pulmonary MZL can present insidiously masquerading as COP and shows the value of (18F) FDG PET/CT to stage extranodal MZL.

[18F]FDG-PET/CT Demonstration of Young Adult Onset Stills Disease Mimicking Lymphoma.

Adult-onset Still's disease (AOSD) is an inflammatory disease of unknown aetiology, with no specific diagnostic tests. A 17-year-old female presented with fevers, night sweats and weight loss. Markedly FDG avid lymphadenopathy, and diffuse marrow and splenic uptake were demonstrated on [18F]FDG-PET/CT, most suggestive of lymphoma. After extensive investigations, the working diagnosis of AOSD was made. Other conditions, such AOSD, in addition to lymphoproliferative disorders, should be considered in the differential diagnosis of widespread avid lymphadenopathy in a teenager/young adult.

Bilateral Avid Axillary Nodes on FDG PET/CT Due to Concurrent Booster COVID-19 Immunization and Seasonal Influenza Vaccination.

ABSTRACT: In an attempt to protect the high-risk demographic and reduce burden on health care systems, concomitant administration of COVID-19 and influenza vaccines has been recommended by health bodies. The ComFluCOV trial indicates this is well tolerated with no reduction in immune response to either vaccine. A 48-year-old woman with right oropharyngeal squamous cell carcinoma underwent postradiotherapy FDG PET/CT, which demonstrated complete metabolic response. Incidental avid bilateral axillary lymphadenopathy of benign configuration was noted and concluded to be reactive in response to recent Pfizer-BioNTech booster and influenza vaccination. This is expected to be seen more frequently over the coming months.

Systemic Immune Response Syndrome After COVID-19 Immunization-Initial and Follow-up 18F-FDG PET/CT Imaging Appearances.

ABSTRACT: A 46-year-old woman with previous history of breast cancer had follow-up 18F-FDG PET/CT 5 days after COVID-19 vaccination. In addition to avid axillary nodes, a well-documented feature, the scan demonstrated diffuse splenic and marrow uptake. Clinical history, laboratory, and scan findings were in keeping with SIRS (systemic inflammatory response). The patient recovered with supportive management. On follow-up, 18F-FDG PET/CT imaging 3 months later features had resolved. SIRS after vaccination may be observed on 18F-FDG PET/CT.

Incidental [18F]PSMA-1007 Appendiceal Uptake Mimicking Nodal Disease.

ABSTRACT: When interpreting an [18F]prostate specific membrane antigen (PSMA)-1007 PET/CT, it is important to understand the normal biodistribution of the tracer. A 73-year-old man with prostate cancer underwent [18F]PSMA-1007 PET/CT for biochemical recurrence. There was no abnormal uptake in the prostatectomy bed, but PSMA-avid pelvic nodal disease was found. Incidental intense focal uptake was also noted corresponding to the tip of the appendix, which was concluded to be physiological. This is an example of an uncommon site of physiological uptake of [18F]PSMA-1007 in the appendix.

Features of Systemic Immune Response From COVID-19 Vaccination on 18F-FDG PET/CT.

ABSTRACT: The rapid rollout of COVID-19 vaccination is accompanied by incidental findings on 18F-FDG PET/CT. Most cases describe reactive axillary lymphadenopathy. A 46-year-old woman with previous history of stage 3A breast cancer underwent follow-up 18F-FDG PET/CT, which demonstrated avid left axillary nodes and intense diffuse splenic uptake and moderate diffuse bone marrow uptake. She had been administered COVID-19 vaccination in the left deltoid 1 week earlier and required hospitalization for 24 hours due to fever. Symptoms settled with supportive treatment. One month after the PET/CT scan, she remained well. Sites of uptake were taken to relate to a systemic immune response.

COVID-19-Related Lung Parenchymal Uptake on 18F-PSMA-1007 PET/CT.

ABSTRACT: A 70-year-old man with newly diagnosed prostate cancer underwent 18F-PSMA-1007 PET/CT for staging. PSMA-avid primary prostatic malignancy was identified. Incidental intense patchy peripheral lung uptake was also noted. The patient tested positive for COVID-19 infection.

Increased FDG Uptake of the Pectoral Girdle and Serratus Anterior Due to Wallpaper Stripping on PET/CT-Exquisite Demonstration of the Biomechanics.

ABSTRACT: According to published guidelines and routine procedures, patients are instructed to avoid strenuous exercise for 6 to 24 hours before FDG imaging, avoiding unfavorable muscular uptake. A 40-year-old man with esophageal carcinoma underwent FDG PET/CT for response assessment. Intense uptake was noted in the muscles of the right upper limb and chest. The patient stated he had avoided exercise before scanning. On further questioning, he was found to be a professional painter and decorator and had been working stripping wallpaper. Marked skeletal FDG uptake occurs in subjects who have strenuously exerted themselves before or after the injection of FDG.

False-Positive Axillary Lymph Nodes on FDG PET/CT Resulting From COVID-19 Immunization.

ABSTRACT: World-wide mass COVID-19 vaccination has been deployed starting with those most vulnerable, including the elderly and cancer patients. A 70-year-old man with right lung cancer underwent staging FDG PET/CT, which demonstrated an avid right lung mass with avid hilar and mediastinal nodes. Avid left axillary nodes of benign configuration were also noted. The patient had the Oxford-AstraZeneca COVID-19 vaccination in the left arm a week earlier. On reflection, the axillary nodes were concluded to be reactive related to this. This is a potential COVID-19 vaccination associated pitfall on PET/CT that should be considered when interpreting FDG PET/CT images.

Infection Control of COVID-19: Surgical Mask-Related Facial Cutaneous Artifact on FDG PET/CT.

ABSTRACT: In accordance with published international COVID-19 pandemic guidance (American College of Nuclear Medicine, British Nuclear Medicine Society, and European Association of Nuclear Medicine), the use of face masks has become an essential part of infection control for both patients and staff. A 56-year-old man with mantle cell lymphoma underwent staging FDG PET/CT, which demonstrated avid lymphadenopathy below the diaphragm and an unusual diffuse FDG uptake projected over the face, raising the suspicion of cutaneous lymphomatous involvement. On reflection of the clinical scenario and scanning conditions, cutaneous involvement was discounted; the pattern of uptake and lack of CT correlate were supportive of a cutaneous artifact related to the presence of the patient's mask.

Pembrolizumab-Induced Thyroiditis and Colitis-Presentation and Resolution on Serial FDG PET/CT.

ABSTRACT: A 58-year-old man with previous melanoma of the left leg underwent whole-body 18F-FDG PET/CT to stage metastatic disease prior to commencing pembrolizumab. Follow-up FDG PET/CT after 3 months of treatment showed partial metabolic response of soft tissue and nodal metastases and diffuse increased thyroid and colonic uptake, suggestive of thyroiditis and colitis. Pembrolizumab was ceased, and a repeat FDG PET/CT scan showed regression of uptake in the thyroid gland and colon, in keeping with resolution of inflammatory change. Immune-related adverse events induced by Immune checkpoint inhibitors, such as pembrolizumab, should be recognized-cessation of treatment often leads to resolution.

18F-Fluorodeoxyglucose PET/CT and dynamic contrast-enhanced MRI as imaging biomarkers in malignant pleural mesothelioma.

PURPOSE: The purpose of this study was to compare the use of fluorine-18-fluorodeoxyglucose (F-FDG) PET with computed tomography (CT) and dynamic contrast-enhanced (DCE) MRI to predict prognosis and monitor treatment in malignant pleural mesothelioma. PATIENTS AND METHODS: F-FDG PET/CT and DCE-MRI studies carried out as part of the South West Area Mesothelioma Pemetrexed trial were used. F-FDG PET/CT and DCE-MRI studies were carried out before treatment, and after two cycles of chemotherapy, on patients treated with pemetrexed and cisplatin. A total of 73 patients were recruited, of whom 65 had PET/CT and DCE-MRI scans. Baseline measurements from F-FDG PET/CT (maximum standardized uptake value, metabolic tumour volume and total lesion glycolysis) and DCE-MRI (integrated area under the first 90s of the curve and washout slope) were compared with overall survival (OS) using Kaplan-Meier and Cox regression analyses, and changes in imaging measurements were compared with disease progression. RESULTS: PET/CT and DCE-MRI measurements were not correlated with each other. Maximum standardized uptake value, metabolic tumour volume and total lesion glycolysis were significantly related to OS with Cox regression analysis and Kaplan-Meir analysis, and DCE-MRI washout curve shape was significantly related to OS. DCE-MRI curve shape can be combined with F-FDG PET/CT to give additional prognostic information. Changes in measurements were not related to progression-free survival. CONCLUSIONS: F-FDG PET/CT and DCE-MRI give prognostic information in malignant pleural mesothelioma. Neither PET/CT nor DCE-MRI is useful for monitoring disease progression.