Triple-phase 99mTc-3P-RGD2 imaging of peripheral primitive neuroectodermal tumor in the hip muscle group with bone metastasis.

Peripheral primitive neuroectodermal tumors (pPNETs) are a group of aggressive neoplasms that are most commonly encountered in pediatric patients and may be located in the abdomen, pelvis, thoracopulmonary region and, rarely, in the head and neck region. pPNETs in adults are extremely rare. The present study reports a case of pPNET located in the hip muscles with bone metastasis. The patient was a 44-year-old woman who complained of progressive pain and swelling with a mass near the left hip. Computed tomography (CT) and enhanced CT revealed a soft tissue mass lesion in the hip muscle group measuring 4.3×4.3×4.4 cm. The lesion was ill-defined, heterogeneous, exhibiting mild post-contrast enhancement. There was a large number of bent neovessels and several branches from the left internal iliac artery and deep femoral artery on enhanced CT scan. Triple-phase dynamic imaging with integrin αvβ3-targeted 99mTc-3P-RGD2 as the radiotracer revealed increased blood perfusion and radiotracer aggregation in the large, ill-defined, heterogeneous, hypodense mass and adjacent bone. The patient was suspected of having pPNET with bone metastasis, which was confirmed by histological examination of a sample obtained by needle aspiration. Due to the high blood perfusion of primary pPNETs and high RGD uptake by the primary and metastatic lesions, chemoembolization and anti-angiogenic therapy were considered to be the optimal therapeutic choice. This also suggested that 177Lu-labeled RGD has great potential for the targeted treatment of pPNETs with multiple metastases.