Residual thymic tissue and lymph node involvement by acute myeloid leukaemia presenting as mediastinal, strongly 18 FDG-PET-positive masses.

We report on a multidisciplinary management of a 68-year-old AML patient presenting with a PET-positive mediastinal tumour typical for lymph node metastasis. It was removed via minimally invasive thoracoscopic intervention and was identified as a thymus residual infiltrated by AML. Follow-up PET-CT scan after resection and remission induction chemotherapy was completely normal. To our knowledge, this is the first documented case report of AML presenting with PET-positive infiltrates of thymic and lymph node tissue along the aortic bow mimicking a second intrathoracic malignancy. Our observation indicates the usefulness of this imaging technique and supports clarification of these unusual findings in AML patients, in case of need also by invasive diagnostic procedures, to enable an adequate therapeutic decision.