Retrospective chart analysis of incidental findings detected by (18) F-fluorodeoxyglucose-PET/CT in patients with cutaneous malignant melanoma

Background and objectives: (18) F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) frequently reveals incidental findings. The present study focused on incidental FDG-PET/CT findings in cutaneous melanoma patients, and verified their relevance with respect to further diagnostic measures and interventions.

Patients and methods: Medical records of 181 consecutive melanoma patients were retrospectively evaluated to verify the management of incidental findings, with particular emphasis on histological findings.

Results: Thirty-three of 181 (18 %) patients showed 39 relevant incidental findings, located in the colorectal tract (n = 15 patients), thyroid (n = 8), prostate (n = 2), locomotor system (n = 2), lymph nodes (n = 2), parotid gland (n = 1), tonsils (n = 1), kidneys (n = 1), and gallbladder (n = 1). Performed in 25 patients, additional diagnostic procedures revealed a clinical correlate in 21 cases. Sixteen of 21 patients had tumoral involvement, including five malignant lesions (four colorectal and one prostate carcinoma). The malignancies were diagnosed at an early stage, and successfully removed in the majority of cases.

Conclusions: The diagnostic use of FDG-PET/CT is routinely recommended for stage IIC melanoma and higher, and is widely accepted as indication. This study effectively identified otherwise undetected cancers, especially colorectal malignancies. Early interventions were possible in most cases. Incidental findings on FDG-PET/CT should be worked up with appropriate diagnostic measures, considering the patient's condition and wishes.