SARCOMATOUS TRANSFORMATION OF NEUROFIBROMAS COMPARATIVE IMAGING WITH GA-67, TL-20, TL-201, TC-99M PENTAVALENT DMSA AND TC-99M MIBI

A 29-year-old man, with a history of von Recklinghausen's disease, pre sented with progressive dyspnea associated with a rapidly growing mass on the right chest wall. Plain radiograph and CT of the chest reveale d a huge soft-tissue mass with central low-density area involving the right upper lung and chest wall. SPECT imaging with Ga-67 citrate, Tl- 201 chloride, Tc-99m pentavalent DMSA (V-DMSA), and Tc-99m MIBI were p erformed to characterize the mass. The tumor concentrated Ga-67, Tl-20 1, and Tc-99m (V) DMSA, but not Tc-99m MIBI. Punch biopsy of the lesio n revealed malignant transformation of a thoracic neuroma (neurofibros arcoma). Subsequently, findings compatible with the presence of a mult idrug resistance-1 (MDR1) gene in the tumor was documented, which may explain the poor uptake of Tc-99m MIBI. The patient did not respond to intensive chemotherapeutic regimens, and died 3 months later. This ca se demonstrates the potential use of combined radionuclide imaging for the detection of malignant transformation of neurofibroma, as well as for predicting tumor response to chemotherapy.