False-Positive Axillary Lymph Node on F-18 FDG PET/CT due to Moxibustion Therapy.

Abstract

A 30-year-old female was diagnosed with papillary thyroid cancer and underwent total thyroidectomy and high-dose radioiodine ablation. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for recurrence detection of thyroid carcinoma was performed at 3 years after total thyroidectomy (Fig. 1). Fig. 1 (a) A projection image demonstrated a focal hypermetabolic lesion in the left axillary region (blue arrow). (b) PET and PET/CT fusion images demonstrated a hypermetabolic lymph node in the left axillary region (maximal SUV 2.5), suggesting lymph node ... Moxibustion is a traditional Chinese medicine therapy using moxa or the mugwort herb. Moxibustion is the burning of a small, thimble-sized, smoldering plug of dried leaves such as moxa or mugwort on the skin at an acupuncture point. Acupuncture and moxibustion induce hyperemia and a local inflammatory reaction. Complications associated with moxibustion such as skin burns or infection of the site have been reported previously [1]. False-positive FDG uptake in PET may result from inflammation, infection, and variations in physiological uptake [2, 3]. In the present case, the hypermetabolic axillary lymph node disappeared without any treatment. Well-known causes of false-positive FDG uptake in axillary lymph nodes such as arthritis of the upper extremity, extravasation of injected FDG, and vaccination were not found [4, 5]. Thus, left axillary lymph node uptake was considered false-positive uptake due to the local inflammatory condition associated with moxibustion.