The vaccine injection sites mimicking metastases of malignant melanoma on FDG PET

The vaccine therapy is an adjuvant therapy combined with chemotherapy in stage III and IV malignant melanoma. Granuloma is a side effect of vaccines. Three stage IV patients were treated with the polyvalent vaccine consist of melanoma cell lysates. All patients have granulomas on injection sites with F-18 fluorodeoxyglucose (FDG) uptakes on PET. Granuloma is an organized collection of macrophages. Macrophages contain intense Glut-1 which is the most important deteminant of F-18 FDG uptake in cells. Granulomas can mimic skin or lymph node involvement of malignant melanoma on F-18 FDG PET.