title: Delayed positive thallium uptake in large B-cell non-Hodgkin's malignant lymphoma.
abstract: We report an unusual finding in an AIDS patient who presented with a large mediastinal mass and multiple lymphadenopathy. A sequential thallium and gallium scan to specify the nature of the mediastinal mass was requested. The early thallium images, acquired 15 min after the intravenous injection, showed no uptake in the mass. The delayed images 2 hr later showed intense thallium uptake. A gallium scan performed 48 hr later also showed intense gallium uptake in the mediastinal mass. Biopsy from the inguinal lymph node confirmed the presence of large-cell diffuse noncleaved malignant lymphoma. This case raises questions about the optimum time of imaging for thallium in high-grade lymphoma, whether delayed imaging is essential, about previous reports of low sensitivity of thallium in undifferentiated lymphoma and about the mechanism of thallium uptake in this type of tumor.
authors.affiliation: Department of Radiology, Saint Vincent's Hospital and Medical Center, New York, NY 10011, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Abdel-Dayem
authors.forename: S Y
authors.initials: SY
authors.lastname: Naddaf
authors.forename: W S
authors.initials: WS
authors.lastname: Omar
authors.forename: M
authors.initials: M
authors.lastname: Aziz
authors.forename: J
authors.initials: J
authors.lastname: Gillooley
mesh_terms: D002951:Citrates; D005708:Gallium; D005710:Gallium Radioisotopes; D006801:Humans; D016483:Lymphoma, AIDS-Related / Q000000981:diagnostic imaging*; D016403:Lymphoma, Large B-Cell, Diffuse / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D013793:Thallium; D013794:Thallium Radioisotopes; D013997:Time Factors
chemical_list: D002951:Citrates; D005710:Gallium Radioisotopes; D013794:Thallium Radioisotopes; C027549:thallium chloride; D013793:Thallium; D005708:Gallium; C103850:gallium citrate