Diagnosis of Atypical Medullary Metastasis in Melanoma Using 18F-FDG PET/CT.

As part of the therapeutic evaluation, positron emission tomography/computed tomography (PET/CT) using 18F-fluorodeoxyglucose (18F-FDG) was performed on a 39-year-old patient with metastatic melanoma of the left thigh who was subsequently receiving immunotherapy. The examination revealed pathologic hypermetabolic foci in the lymph nodes and liver along with a highly suspicious pathologic hypermetabolic foci in the spinal marrow at the level of the first lumbar vertebra (L1). The presence of such a hypermetabolic focus can significantly decrease survival duration, highlighting the importance of early detection. PET/CT with 18F-FDG proved to be more sensitive and specific than CT alone in identifying occult distant metastases, as the latter may underestimate malignant involvement of the spinal marrow.