Introduction/Background Sternal metastases of breast cancer are rare. Their occurrence is due to the spread of malignant cells via the hematogenous route or via a local pathway from the internal mammary nodes.

The aim of this study is to define the different pattern of sternal malignant abnormalities on bone scan.

Methodology It is a retrospective study including breast cancer patients, referred for bone scan during 2019, at the Nuclear Medicine department of Tlemcen University Hospital in Algeria.

Two hours after the intravenous injection of 8–10 MBq/kg 99mTc-HMDP, whole body scanning is accomplished by dual head hybrid gamma camera with low energy high resolution collimator. The SPECT/CT (single photon emission tomography/computed tomography) acquisition is used to better characterize the presence, location, and extent of disease in some patients.

Results A total of 54 malignant sternal abnormalities were found in 500 breast cancer patients (10,8%).

Half of the lesions (27 cases) were located in the sternal body, 17 (32%) in the manubrium and 10 (18%) in the entire bone structure.

The majority of sternal abnormalities (47 cases; 87%) was found as a part of multiple metastases, while only 2 cases (4%) as a part of oligometastases and 5 cases (9%) as the initial site of bone metastases.

A solitary sternal uptake on bone scan is difficult to interpret due to various etiologies, both benign and malignant. The SPECT/CT acquisition has allowed us to define the secondary origin of the radioactivity uptake after cross sectional study and confrontation with morphological imaging.

The predominant scintigraphic pattern was that of hot lesions (48 cases; 89%), which highlights an osteoblastic hyperactivity. A cold lesion representing an osteoclastic activity, is rarely seen in bone scan until it is surrounded by an increased radioactivity uptake. The latter aspect was found in 6 patients (11%).

Conclusion Radionuclide bone scintigraphy is a useful tool for recognizing sternal abnormalities in breast cancer patients.

Disclosures We have no disclosures.