Expression of CXCR4 Receptors in Refractory Atypical Mediastinal Carcinoid.

Primary neuroendocrine tumor of the mediastinum is a relatively rare entity. In metastatic/inoperable disease, therapeutic options are limited to cytotoxic chemotherapy in poorly differentiated tumors and peptide receptor radionuclide therapy in case of well-differentiated tumors. We present the case of a 52-year-old man with mediastinal atypical carcinoid (grade II) neuroendocrine tumor showing mild somatostatin receptor expression and intense FDG avidity with progressive disease on chemotherapy. Chemokine receptor targeted PET/CT with CXCR4 (Ga-CXCR4) showed tracer avidity in tumor sites higher than the physiological sites, which may pave the way for CXCR4-targeted radionuclide therapy in this subgroup of patients.