Positron emission tomographic scanning with a near-simultaneous computed tomography scan is the preferred imaging modality for staging lymphomas. PET scanning detects Hodgkin lymphoma as well as the aggressive and most indolent non-Hodgkin lymphomas.
PET-CT is the standard of care for remission assessment in patients with fluorodeoxyglucose -avid lymphomas, including Hodgkin lymphoma. The use of PET-CT scans for restaging is not without pitfalls.
A 45-year-old woman visited a lymphoma clinic with complaints of intermittent fevers and night sweats of several months duration. A CT scan of the chest revealed lymphadenopathy, while subsequent PET-CT scan showed hypermetabolic foci within the left neck, left axilla, and mediastinum, suggestive of Hodgkin lymphoma.
Kikuchi’s disease (Kikuchi–Fujimoto disease), known as histiocytic necrotizing lymphadenitis, is a benign, self-limiting disorder, cervical lymphadenopathy, fever, and leukopenia.
FDG–PET-CT has become the standard of care for staging patients with FDG-avid lymphomas such as Hodgkin lymphoma and diffuse large B-cell lymphoma. PET is recommended for post-treatment assessment and is the best way to define a complete remission. However, several infectious, inflammatory, and non-neoplastic conditions can result in false-positive PET scans.
Cases reported conditions like thyrotoxicosis, fat necrosis, tuberculosis, sarcoidosis, fungal infections, syphilis, and infectious mononucleosis are misdiagnosed as lymphoma based on PET scans. Hence, it is important to proceed cautiously with patients in whom disease progression is suspected with typical findings where radiologic improvement in one site and new lymphadenopathy in another.
Ref: https://ascopubs.org/doi/full/10.1200/JOP.2015.009910
