The diagnosis of patients with fever of unknown origin (FUO) in pediatric heart transplantation is a challenging medical problem. The physician should differentiate between rejections, infections, malignancy, adrenal insufficiency, and drug fever. Immunosuppressive therapy in these patients exposes them to a high risk of developing a post-transplantation fungal infection. In this case, we discuss the diagnostic contribution of the 99mTc-UBI scan and 18F-FDG PET scan for diagnosis of fungal infection causing FUO in these patients.

The 18F-FDG PET/CT imaging is a non-invasive modality for diagnosis and staging of metastatic melanoma. Venous thromboembolism (VTE) is a common complication of cancers, which needs anticoagulant therapy. Tumor thrombosis (TT), on the other hand, is an infrequent complication of solid malignancies that may need aggressive management. Accurate diagnosis of TT and its differentiation from VTE may change patient management and avoid unnecessary anticoagulation treatment. The objective of this case is to introduce a patient with malignant melanoma presenting with extensive venous tumor thrombi with intense FDG uptake.