Lung Parasite Ova Granuloma Mimicking Lung Malignancy on FDG PET-CT

Colonic Parasitic Infection Mimicking Peritoneal Seeding on 18F-FDG PET/CT

A 77-year-old man with anorexia and weight loss for 6 months received a diagnosis of gastric cancer by endoscopy and referred for F-FDG PET/CT for initial staging. F-FDG PET/CT showed multiple foci of increased FDG uptake with diffuse wall thickening and multiple diverticula. The differential diagnoses were peritoneal seeding and multiple diverticulitis. The patient underwent curative total gastrectomy, and the lesion was diagnosed as poorly differentiated adenocarcinoma by histological examination. He underwent anterior resection of the sigmoid colon for exploration. The nodular lesions of the sigmoid colon were diagnosed by histopathologic examination as chronic diverticulitis caused by a parasitic infection.

18F-FDG PET/CT in a case of parasite infection mimicking lung and breast malignancy

A 51-year-old woman with dyspnea on exertion, fever, pleural effusion, and pericardial thickening underwent F-FDG PET/CT, which revealed focal hypermetabolic lesions in the right lung and left breast. The histopathology of the lesions was compatible with infiltration of inflammatory cells. Blood eosinophil counts were elevated, and enzyme-linked immunoassays were positive for antibodies to several parasites. After antiparasite medication, blood eosinophil counts were normalized, and PET/CT demonstrated complete disappearance of abnormal FDG accumulation in the lung and breast.

18F-FDG PET/CT features of pulmonary sclerosing hemangioma

BACKGROUND

Pulmonary sclerosing hemangioma (PSH) has been reported to show increased FDG uptake and be potential false-positives on 18F-FDG PET/CT examination. However, it is still unclear whether the previously-reported high FDG uptake is a universal characteristic of PSH, and furthermore, there have been no investigations on what kind of radiologic or histologic features may have been related with its FDG uptake values.

PURPOSE

To investigate the 18F-FDG PET/CT features of pulmonary sclerosing hemangiomas (PSHs), and to evaluate the relating factors with their FDG uptake values.

MATERIAL AND METHODS

We identified 10 PSHs in eight patients who had a pathologic diagnosis and available antecedent 18F-FDG PET/CT images. 18F-FDG PET/CT images were investigated both qualitatively and quantitatively, along with their histopathologic features. Correlation between 18F-FDG PET features and radiologic as well as histopathologic features were also evaluated.

RESULTS

Mean diameter of the 10 PSHs in our study was 16.9 mm ± 6.26 (range 5-25 mm). Four tumors showed intense uptake, and four tumors showed moderate uptake on 18F-FDG PET/CT scans. In the remaining two tumors, there were no significant FDG uptakes. The SUVmax of tumors ranged from 0.60-4.7 (median 2.30; 2.51 ± 1.42), and was significantly correlated with the tumor size (r = 0.754, P = 0.012) and three out of four tumors ≥2 cm (75%) showed intense FDG uptake and their SUVmax values were greater than 2.5. Immunohistochemical results for GLUT-1, GLUT-4, and Ki-67 and other pathologic features were not correlated with the tumors' FDG uptake.

CONCLUSION

The majority of PSHs show increased FDG uptakes, and their SUVmax values are significantly correlated with their tumor size. PSH ≥2 cm can frequently be falsely interpreted as malignancy in FDG-PET/CT. Further studies with large study population are warranted to confirm our observations.

F-18 FDG PET/CT in evaluation of pulmonary sclerosing hemangioma

PURPOSE

Pulmonary sclerosing hemangioma (PSH), or the alternative name of "sclerosing pneumocytoma," is a rare benign neoplasm. PSH is often asymptomatic and presents as a solitary pulmonary nodule on radiologic imaging studies. Few articles have been reported to describe the FDG PET findings about PSH. We reported FDG PET findings of 6 cases of PSH and reviewed the literatures.

MATERIALS AND METHODS

FDG PET and PET/CT imaging studies of 6 patients with proven PSH were reviewed. The relation between the degree of FDG uptake and tumor size was analyzed.

RESULTS

All 6 tumors were detected by FDG PET or PET/CT. Mean diameter of these tumors was 2.9 cm. Mean standard uptake value was 2.45 (range, 1.8-3.93). The maximal standard uptake value of FDG uptake was positively correlated with the tumor size (R = 0.9694, P < 0.05).

CONCLUSIONS

PSH demonstrates low to moderate uptake on FDG PET imaging. The larger PSH has higher uptake and might be misrecognized as a malignancy. The possibility of false-positive result caused by PSH should be considered while interpreting FDG PET images of solitary pulmonary nodules.

Solitary necrotic nodule with larval infestation in the liver on F-18 FDG PET/CT

We present the case of a 64-year-old woman who suffered from occasional right upper abdominal pain for several months. Both abdominal ultrasonography and magnetic resonance imaging showed a hepatic mass of indeterminate nature. F-18 FDG PET/CT showed a solitary hypermetabolic mass in the liver; a malignancy was therefore suspected. Her hepatic tumor was resected; it was a solitary necrotic nodule with larval infestation but no evidence of malignancy.

Hepatic paragonimiasis revealed by FDG PET/CT

A 72-year-old asymptomatic man with a hepatic lesion incidentally detected by ultrasonography in routine examination undertook fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography for further evaluation. The images revealed increased FDG activity in the lesion, which was suggestive of malignancy. However, the pathologic examination demonstrated that the lesion was a granuloma caused by Paragonimus westermani, a lung fluke. Although increased FDG activity in the lung due to P. westermani infection is expected and reported previously, such lesion identified in the liver by FDG positron emission tomography/computed tomography is unusual.