Plain X rays of pelvis and right limb were normal.
Since pain persited, a CT scan was ordered.
Teaching points:
PET/CT is indicated for staging and re-staging of melanoma.
The technique has high sensitivity for detecting bone marrow involvement.
Although conventional bone scanning is sueful, PET/CT has the power of detecting also soft tissue involvement (in this case, however, the thyroid finding does not add to the prognosis).
Thyroid metastases from melanoma are no frequent. One paper reports on 5 incidental findings of thyroid metastases with FDG: 2 from melanoma, 2 from colotrectal cancer, 1 from gastric cancer.
Primary malignant thyroid carcinoma, especially papillary type, also take up FDG.
