Incidental Detection of Metastatic Malignant Melanoma on 68Ga–Prostate-Specific Membrane Antigen PET/CT Imaging: Correlative Imaging With FDG PET/CT and Review of the Literature
An 80-year-old man with suspected recurrent prostate carcinoma underwent 68Ga-PSMA PET/CT, which showed enlarged axillary lymph nodes with intensely increased 68Ga-PSMA uptake, an atypical site for prostate cancer metastasis. Fine-needle aspiration biopsy revealed metastatic malignant melanoma. FDG PET/CT revealed congruent intense FDG uptake. Therefore, malignant melanoma should be included in the list of malignancies that can be seen positive on 68Ga-PSMA PET/CT. In unclear 68Ga-PSMA PET–positive lesions, further clarification with other imaging techniques or biopsy is mandatory to avoid scan misinterpretation. Review of the literature revealed other non–prostate cancer causes of elevated PSMA uptake classified into neoplastic and nonneoplastic conditions.