Abstract
Metastasis from unknown primary is always a challenge because finding the true primary tumor significantly affects subsequent management. We present a case of malignant abdominal wall nodule initially diagnosed as metastasis from hepatocellular carcinoma through excisional biopsy and immunohistochemical (IHC) staining. Dual-tracer positron emission tomography/computed tomography (PET/CT) with (11)C-acetate and (18)F-FDG, however, showed metabolic findings in favor of metastasis from lung origin, which was finally confirmed by ensuing a lung biopsy with additional IHC stains. This case illustrates the complementary molecular role of PET to pathology, particularly when dual-tracer or multi-tracer PET is used in conjunction with pathology methods for cross referencing and confirmation.