Background: Medullary thyroid carcinoma (MTC) belongs in the group of neuroendocrine tumors with early lymphatic and hepatic dissemination. A high rate of undetectable metastases is hypothesized to be responsible for the frequent mismatch between the apparent relatively small tumor burden and the elevated plasma tumor marker level.
Methods: Thirty-six MTC patients with residual/recurrent biochemical signs (elevated basal calcitonin level) and/or characteristic general symptoms (diarrhea and/or flushing) were systematically examined by conventional radiology, whole-body 18F-deoxyglucose positron emission tomography (PET), dynamic liver computed tomography and magnetic resonance imaging, and hepatic angiography.
Results: Conventional diagnostic imaging revealed lymph node (LN) involvement in the cervical, mediastinal, supraclavicular, and axillary regions (16 cases), and multiple pulmonary (3 cases), bony (1 solitary and 1 multiple case), and breast (1 case) metastases. (18)F-deoxyglucose PET identified all these extralymphatic metastatic lesions (except 2 cases with multiple pulmonary metastases), and also supradiaphragmatic LN involvement in 34 (94%) patients. In 32 (89%) cases, multiple small (generally < or = 1 cm) hypervascular, hepatic metastases undetectable by other imaging methods were localized angiographically. Of the 23 original pathologic specimens investigated, 18 (78%) exhibited LN involvement. The smallest primary tumor in patients with hepatic metastases was 1 cm.
Conclusions: Hepatic angiography is recommended for primary staging in MTC patients with a primary tumor measuring 1 cm or larger, and/or pathologically proven LN involvement, and also during restaging for suspected recurrences to avoid unnecessary extensive surgical LN dissection in the neck and mediastinum.
Copyright 2001 American Cancer Society.