False-positive axillary lymph node on positron emission tomography/computed tomography in a thymoma patient with a tattoo

positive axillary lymph node on positron emission tomography/computed tomography in a thymoma patient with a tattoo. A 42-year old woman presented with a mediastinal tumour and left axillary lymphadenopathy (Fig. 1), 24 years after tattooing (Fig. 2). Thymectomy and diagnostic biopsy of the left axillary lymph nodes were performed. Histopathology showed a type A, Masaoka stage I thymoma, and reactive lymphadenopathy caused by tattoo pigments (Fig. 2). 18 F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography revealed high FDG uptake in the tumour and in a left axillary lymph node, with a maximum standardized uptake value of 8.69 and 8.97, respectively. Figure 2: (A) On physical examination, the presence of a large decorative tattoo was noted on the patient's back and left forearm, which she had obtained 24 years before admission. (B) The axillary histopathology showed lymphoid tissue and abundant black pigmentation (haematoxylin and eosin staining ×40).