Unusual Breast Metastasis from Atypical Lung Carcinoid on 68Ga-DOTATATE PET/CT

Background: Atypical carcinoid (AC) is one of the rarest lung neuroendocrine tumors (NETs) that rarely metastasize to the breast, and only a few cases have been reported in the literature. Positron emission tomography/computed tomography (PET/CT) with somatostatin analogs (SSAs) labeled with Gallium-68 (Ga-68) now represents the gold standard for diagnosis and management of NETs. A case of an unusual metastasis to the breast from an AC detected by Ga-68-DOTATATE PET/CT was reported. Case Presentation: A 73-year-old woman was presented with a right breast lesion found on mammography screening, which revealed a metastatic neuroendocrine tumor by histopathological analysis with a tru-cut biopsy. Subsequently, Ga-68-DOTATATE PET/CT imaging performed for the initial evaluation showed increased radiotracer uptake in the lesion in the right breast as well as the nodular lesion in the middle lobe of the right lung, which was histologically confirmed to be AC. Conclusion: Metastasis of uncommon AC of the lung to the breast is extremely rare. However, it is essential to properly differentiate metastatic tumors from primary disease due to differences in clinical management and prognosis, and Ga-68-DOTATATE PET/CT is a unique diagnostic tool with the advantage of whole-body imaging.