18 F-FDG uptake in the thymus, mainly related to hyperplasia after chemotherapy, has been described. Thymic uptake can challenge the accurate assessment of cancer patients by 18 F-FDG imaging. The present study defines the incidence, patterns, and intensity of thymic 18 F-FDG uptake in relationship to age and time after treatment in a large cohort of patients. Methods: A total of 559 consecutive 18 F-FDG PET/CT studies in 160 patients (86 men, 74 women; age, 3-40 y) performed at baseline, during treatment, at the end of treatment, and during follow-up were retrospectively reviewed. PET/CT studies were assessed for the presence or absence (T1 or T2, respectively), pattern, and intensity (SUVmax) of increased 18 F-FDG uptake in the anterior mediastinum, localized by the CT component to the thymus. The overall incidence of 18 F-FDG avidity in the thymus in relationship to the patient's age and time after treatment administration were statistically evaluated. Results: There were 137 of 559 T1 studies (25%), with equal sex distribution. T1 studies were found in significantly younger patients (20.6 6 9.3 y vs. 27.4 6 8.4 y, P , 0.001). Most T1 patients (60%) showed an inverted V pattern of thymic uptake, with additional unilateral mediastinal extension in 24% and focal midline uptake in 16% of studies. T1 studies were encountered in 80% of patients younger than 10 y, compared with 8% of patients in the 31-to 40-y age group. There were 17% T1 studies at baseline, 6% during treatment, 8% at the end of treatment, and 27%-40% during follow-up. The average SUVmax of thymic 18 F-FDG uptake was 3.73 6 1.22. Conclusion: Thymic 18 F-FDG uptake was found in 28% of the present study population, more frequently after treatment. T1 patients were significantly younger. Thymic uptake was found in 73% of untreated patients up to the age of 13 y and in 8% of patients in the fourth decade of life. Knowledge of this age-and treatmentrelated incidence of physiologic thymic 18 F-FDG avidity can reduce the number of potential pitfalls in reporting PET/CT studies in cancer patients.

The protozoan Blastocystis hominis has been considered nonpathogenic, but this classification has come under scrutiny in light of reports in the medical literature indicating it could be the cause of intestinal disorders and, in one case, hypoalbuminemia. Reported here is a severe case of infection with B. hominis that caused acute gastroenteritis with prolonged diarrhea, hypoalbuminemia and anasarca. The diagnosis was based on the parasitological finding, since no other pathological evidence was found. The patient responded favorably to treatment with metronidazole for 10 days. This case supports the idea that B. hominis should be considered as a cause of opportunistic infection in debilitated patients despite the controversy surrounding its pathogenicity.

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We report the case of 19-year-old woman with severe hypercalcemia who was evaluated with a bone scan to exclude bone metastases. Increased uptake in both lungs was detected on the bone scan. The patient's final diagnosis was systemic lupus erythematous (SLE). There is no reported pattern of bone scanning in SLE, and diffuse lung uptake has not been reported in these patients.

Limping is a frequent occurrence in children and may be caused by various conditions, including trauma, inflammation, infection, and malignancy. Nontraumatic avascular necrosis of the tarsal bones should be included in the differential diagnosis. Accumulated data have supported the superiority of bone scans to radiography in the early diagnosis of avascular necrosis. Bone scintigraphy is a useful tool for investigating pain when symptoms, laboratory examinations, and radiography do not point to a specific diagnosis. In the early phase of disease, bone scans may demonstrate decreased tracer uptake (photopenic region), subsequently a hot area is seen during the reparative process. Although magnetic resonance imaging has important implications in the diagnosis of avascular necrosis, bone scintigraphy with its ready availability has a significant role as a primary tool in the evaluation of a limping child.