Imaging features of carcinoid tumors metastatic to the breast

The objective of this study was to describe the imaging findings of carcinoid tumors metastatic to the breast, with pathologic and clinical correlations. We searched our surgical database for cases of pathologically proven carcinoid tumors metastatic to the breast from October 1, 2000, to May 31, 2010. Of the approximate 10,000 breast biopsies identified, 7000 had malignant findings. Ten cases of metastatic carcinoid (0.1% of all malignancies), all with imaging studies available for review, were included in the study. All patients were women and had their primary carcinoid in the gastrointestinal tract (n = 9) or lung (n = 1). One patient presented with a palpable breast mass and no history of carcinoid tumor; an ileal carcinoid was discovered after the pathologic diagnosis of metastatic carcinoid was established. In the breast, tumors presented as solitary lesions in half the cases. Metastases to the breast typically presented as circumscribed masses mammographically and as hypoechoic circumscribed masses ultrasonographically; some showed increased through-transmission and increased vascularity with color Doppler evaluation. Five patients had octreotide scans; of these, 4 had increased focal activity in the region of metastasis within the breast. Six patients underwent computed tomography. Without contrast, nodular masses were observed; with contrast, the masses showed rapid enhancement during arterial phase imaging. Magnetic resonance imaging (n = 4) also showed rapid enhancement and washout kinetics after contrast administration. Recognition of carcinoid metastases to the breast in patients with known or occult primary carcinoid tumors is important to avoid unnecessary treatment for primary breast cancer.