18F‐Fluorine‐18‐l‐dihydroxyphenylalanine (18F‐DOPA) positive isolated peritoneal carcinomatosis from a MENII‐related medullary thyroid carcinoma. About an atypical metastatic site and utility of 18F‐FDOPA

A patient, operated for a medullary thyroid carcinoma (MTC) with a positive RET mutation, showed several peritoneal nodes on a computed tomography (CT), with increased Thyrocalcitonine. A ¹⁸F‐Fluorine‐18‐l ‐dihydroxyphenylalanine (18‐F‐FDOPA) positron emission tomography (PET/CT) showed isolated tracer uptake on the nodes. A biopsy confirmed that it was from the MTC, with the same RET mutation as in blood.