Ameboma Mimicking Lung Cancer on FDG PET/CT

Successful Diagnosis of a Longstanding Giant Amoebic Liver Abscess Using Contrast-Enhanced Ultrasonography (CEUS): A Case Report in a Western Country

BACKGROUND E. histolytica liver abscess results from extra-intestinal diffusion of amebiasis, which is responsible for up 100 000 deaths per annum, placing it second only to malaria in mortality. Currently, the criterion standard for the diagnosis of liver abscesses is ultrasound, but CEUS (contrast-enhanced ultrasound) is emerging as a more accurate method for liver study, and it could be more accurate than ultrasound and non-invasive compared to CT. CASE REPORT A white man (59 years old) with a 2-day history of dyspnea, acute abdominal pain in right upper quadrant, and raised inflammatory markers was admitted to a second-level Emergency Department in Rome (Italy). He reported several trips to tropical areas many years before, during which he ingested non-potable water and became infected with Entamoeba histolytica. This was treated medically with success. After administration of antibiotics (meropenem and metronidazole), a liver CEUS (contrast-enhanced ultrasonography) with administration of SonoVue (sulphur hexafluoride microbubbles) confirmed a giant liver abscess (15×16 cm). One day later, CT-guided drainage was performed without complications and the patient was discharged on the 25th post-procedure day, with improved blood results. CONCLUSIONS Acute abdominal pain can be caused by a variety of diseases, but a diagnosis of parasitic abscess should not be overlooked in non-endemic Western countries. CEUS is a new, promising, and more accurate technique that can be utilized to recognize liver abnormalities, including abscesses; however, retrospective population-wide studies are necessary to define the differential diagnoses.

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.

FDG PET/CT Findings in Multiple Splenic Amebomas (Amebic Granulomas)

Splenic ameboma (amebic granuloma) is rare. A 38-year-old man with a severe pneumonia due to inhalation of swimming pool water 18 months ago complained of night sweat, tiredness, and anorexia for 1 month. Abdominal ultrasound showed multiple nodules in the spleen. These nodules showed slight enhancement on enhanced CT and intense FDG uptake on PET/CT. Splenectomy was performed. Multiple splenic amebomas were confirmed by pathology. Free-living amoebae were also detected in samples of pleural effusion and blood. Splenic ameboma, although rare, should be included in the differential diagnosis with isolated focally increased FDG activity in the spleen.

Intestinal pork tapeworm disease mimicking lymphoma on PET/CT imaging

A 17-year-old girl with abdominal pain for 3 months underwent 18F-FDG PET to evaluate possible malignancy due to unexplained ascites detected by ultrasound. The images demonstrated multiple foci of abnormally increased 18F-FDG activity in the lymphadenopathy from the neck to the abdomen and in the thickened intestinal wall. In addition, abnormal activity was noted in the pharynx and skeletons. Cysticercosis was confirmed pathologically.

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.