Melanoma and Interferon Therapy

            Nineteen year old male with clinical history of melanoma Clark 3 in the right knee. A year ago underwent adequate surgical tumor removal. At that time, a radionuclide and blue dye sentinel node detection demonstrated 2 inguinal nodes, whose biopsy showed micrometastasis in one of them. Currently under IFN therapy. On PET-CT study, there is no abnormal uptake in the right leg. Bilateral lymphnodes less than 2 cm are seen in the inguinal, iliac and lung hilum regions, with maximun SUV of 5 in the left iliac side (yellow arrows in the transaxial fusion and coronal slices and black arrows in coronal slice to the right hand side). They could be inflammatory or malignant, so a biopsy was decided at the oncology committee, which demonstrated an inflammatory process. On 19/10/2011 Left inguinal lymphnode was excised. Macroscopic examination node of 2 x 1.4 cm. Histological examination: Chronic lymphadenitis predominantly follicular. No metastasis of melanoma.

            PET-CT FDG is being used increasingly in melanoma for its high sensitivity. Nevertheless, false positives are not rare due to a variety of inflammatory conditions, dimishing the specificity (1,2). In many cases a biopsy of the lesion will be necessary to establish the definitive diagnosis. Kalkanis et al published a case with similar findings in the thoracic area to the one presented herein  (3).

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