Primary Renal Leiomyosarcoma Presenting with Subcutaneous and Osseous Metastases: Staging and Follow-Up with 18F-FDG PET/CT.

A 60 year old woman who presented with multiple small subcutaneous nodules in the upper back and arms, was referred for an [18F] fluoro-2-deoxy-D-glucose (F-FDG) positron emission tomography/computed tomography (PET/CT) after histological evaluation revealed metastatic leiomyosarcoma of unknown origin. The PET/CT showed multiple F-FDG-avid subcutaneous nodules, bone lesions, as well as a large left renal mass, which was biopsied to confirm a primary renal leiomyosarcoma arising from the renal parenchyma. A post therapy PET/CT showed overall progression of disease. The use of F-FDG PET/CT in the staging and evaluation of response to therapy of a renal leiomyosarcoma has not been previously described in the literature.