Byung Wook Choi

Cervical tuberculous lymphadenitis mimicking distant lymph node metastasis on F-18 FDG PET/CT in a patient with gastric carcinoid tumor.

A 35-year-old man was diagnosed with gastric carcinoid tumor and underwent whole body F-18 FDG PET/CT for staging. F-18 FDG PET/CT showed no abnormal uptake in the stomach. However, there was increased uptake in the right cervical lymph nodes. An open biopsy of the lymph node confirmed tuberculous lymphadenitis without malignancy. The increased uptake of cervical lymph nodes on F-18 FDG PET/CT imaging should be interpreted with caution in differentiating benign from malignant lesions and should be confirmed by pathologic examination before the initiation of a definitive treatment.

Simultaneous splenic and colonic metastases from gastric cancer: different FDG avidities according to the density of cancer cells imaged on FDG PET/CT.

We describe the ¹⁸F-FDG PET/CT findings of 2 simultaneous metastatic gastric cancers to the colon and spleen with quite different FDG avidities. Longitudinal and weak FDG uptake was observed in the descending colon; therefore, it could not be distinguished from nonpathological functional uptake of normal colon. Meanwhile, the splenic mass showed intense uptake. Contrast-enhanced CT revealed a segmental wall thickening of the descending colon as well as a hypoattenuating splenic mass suggesting metastases. Splenectomy and left hemicolectomy were performed. Histological diagnosis disclosed metastatic gastric cancer. The differential diagnoses and review of the literature are presented.

Extraosseous bone tracer accumulation of the liver on 99mTc-HDP bone scintigraphy in intermittent bleeding after iatrogenic liver injury.

A 69-year-old man with common bile duct cancer and deep jaundice had complained of abdominal pain after percutaneous transhepatic biliary drainage. The laboratory workup showed reduction of serum hemoglobin level after the procedure. A 99mTc-hydroxy diphosphonate bone scan was performed for further evaluation of common bile duct cancer, and there was no abnormality of the skeletal structures. However, diffuse and hazy increased radiotracer uptake was detected on the liver. Follow-up contrast-enhanced 99mCT revealed hematoma and subcapsular hemorrhage of the liver.

Cerebral Toxoplasmosis in a Patient with AIDS on F-18 FDG PET/CT.

The distinction between primary central nervous system (CNS) lymphoma and nonmalignant lesions due to opportunistic infections, in particular cerebral toxoplasmosis, is important because of the different treatments involved. A 32-year-old patient with AIDS was hospitalized for intermittent headaches. Brain magnetic resonance imaging (MRI) showed a small well-enhanced nodular lesion in the right frontal lobe. A fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET)/computed tomography (CT) scan showed moderate FDG uptake in the nodular lesion of the right frontal lobe. We present a case of cerebral toxoplasmosis in a patient with acquired immunodeficiency syndrome (AIDS) and the usefulness of F-18 FDG PET/CT in the differential diagnosis of the cerebral toxoplasmosis will be discussed.

Diagnostic accuracy of 18F-FDG PET/CT for detecting synchronous advanced colorectal neoplasia in patients with gastric cancer.

AbstractPreoperative screening for synchronous colorectal neoplasia (CRN) has been recommended in patients with gastric cancer because patients with gastric cancer are at increased risk for synchronous CRN. The aim of this study was to investigate the diagnostic accuracy of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for detecting synchronous advanced CRN in patients with gastric cancer.A total of 256 patients who underwent colonoscopy and 18F-FDG PET/CT for preoperative staging were enrolled in this study. The diagnosis of focal colonic 18F-FDG uptake on 18F-FDG PET/CT image was made based on histopathologic results from the colonoscopic biopsy. The 18F-FDG PET/CT result was considered as true positive for advanced CRN when focal 18F-FDG uptake matched colorectal carcinoma or adenoma with high-grade dysplasia in the same location on colonoscopy.Synchronous advanced CRN was detected in 21 of the 256 patients (4.7%). Sensitivity, specificity, and accuracy of 18F-FDG PET/CT were 76.2%, 96.2%, and 94.5%. The size of CRN with a true positive result was significantly larger than that with a false negative result.18F-FDG PET/CT demonstrated high diagnostic accuracy for detecting synchronous advanced CRN in patients with gastric cancer. Colonoscopy is recommended as the next diagnostic step for further evaluation of a positive 18F-FDG PET/CT result in patients with gastric cancer.

Eosinophilic infiltration in the colon and liver mimicking primary colon cancer with hepatic metastases on (18)F-FDG PET/CT.

We describe the case of a 78-year-old man presenting with abdominal pain and a weight loss of 5 kg over 2 months. Colonoscopy and abdominal CT suggested colon cancer of hepatic flexure. F-FDG PET/CT scan showed moderate FDG uptake lesion at the hepatic flexure colon and multiple foci of FDG accumulation in the liver. These were considered as colon cancer with multiple hepatic metastases. However, the pathologic finding of colonoscopic biopsy and CT-guided liver biopsy showed only eosinophilic infiltration and no evidence of malignancy.

Usefulness of F-18 FDG PET/CT in the evaluation of neck swelling in polymorphic posttransplant lymphoproliferative disorder after renal transplantation.

A 38-year-old man with a history of renal transplantation presented with a 3-month history of bilateral neck swelling. Ultrasonography of the neck showed multiple enlarged lymph nodes at the bilateral neck. Histologic examination of a specimen from an excisional biopsy at right level II cervical lymph node revealed polymorphic posttransplant lymphoproliferative disorder. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography scan was performed for further evaluation. The scan revealed marked enlargement and intense hypermetabolism of the lymph nodes along the bilateral cervical lymph node chains (Fig. 1). Several reports have described that diverse infectious or inflammatory disorders and malignant diseases show various degree of FDG uptake of cervical lymph nodes. This case illustrates that the possibility of posttransplant lymphoproliferative disorder should be considered in renal transplant patients with increased FDG uptake of cervical lymph nodes on F-18 FDG positron emission tomography/computed tomography scan.

Metastatic colon cancer to the lung with no detectable primary tumor, mimicking advanced primary lung cancer on F-18 FDG PET/CT imaging.

An 83-year-old man was referred with a right lung mass on dynamic chest computed tomography (CT). F-18 fluoro-deoxy-glucose positron emission tomography (FDG PET)/CT showed intense FDG uptake in the right lung mass and bilateral hypermetabolic mediastinal lymph nodes. CT-guided biopsy of the right lung mass revealed metastatic adenocarcinoma from the colon, but a colon cancer lesion was not detected by dynamic abdominal CT and colonoscopy.