Metastatic Melanoma

Metastatic Melanoma

Michael P. Federle, MD, FACR

Amir A. Borhani, MD

(Left) Axial CECT in a middle-aged man with cutaneous melanoma and a distended abdomen shows massive, malignant ascites due to peritoneal metastases image. Also noted are metastases to the perirenal space bilaterally image. (Right) Axial CECT in the same patient shows additional metastases to the peritoneum image, abdominal wall image, lymph nodes, and perirenal space image. “Unusual” sites of metastases are typical in patients with melanoma.

(Left) Axial PET/CT shows FDG-avid metastases in the kidney image and perirenal space image. (Right) Axial PET/CT in the same patient shows an additional lesion in the bowel image. Despite the large size of the metastasis, there was no bowel obstruction.



  • Spectrum of metastatic lesions originating from known or occult malignant melanoma


General Features

  • Best diagnostic clue

    • Multiple “bull’s-eye” lesions of variable size in GI tract of patient with history of melanoma

  • Location

    • Most common sites of metastases: Skin, lymph nodes (75%), lung (70%), liver (58%), CNS (54%), GI tract (40%)

    • Most common involved sites in abdominal cavity include liver and small bowel

  • Morphology

    • Typically multiple, in any site of body

    • Well-circumscribed, spherical or oval

    • Nodule, plaque, polypoid mass

    • “Bull’s-eye” or “target” lesion (central ulceration)

Imaging Recommendations

  • Best imaging tool

    • CECT, PET/CT best for total body screening

      • Sensitivity and specificity are ↑ by simultaneous interpretation of diagnostic quality CT

      • Melanoma may not be FDG avid or may be misinterpreted as normal bowel or kidney on PET

  • Protocol advice

    • Triphasic CECT

      • Hepatic metastases may not be visualized on monophasic CECT

      • 86% of hepatic lesions are detected on portal venous phase as hypodense lesions

Jun 8, 2016 | Posted by in GENERAL RADIOLOGY | Comments Off on Metastatic Melanoma

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