Skin Manifestation of Unsuspecting Prostate Cancer Detected by 18F-FDG PET/CT Performed To Assess Underlying Multiple Myeloma

Background: Skin metastases from either prostate adenocarcinoma or multiple myeloma rarely occur. We report the case of a 73-year-old man with multiple myeloma who presented with multiple subcutaneous nodules 3 years after his initial diagnosis. Methods: Fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) imaging was suggestive of a concomitant second primary from the prostate. Results: This case highlights not only a rare initial manifestation of prostate cancer, but also the role of 18F-FDG-PET/CT in detecting a clinically unsuspected second malignancy. Conclusion: It potentially corroborates the possible association of both diseases, as has been reported before.