Lumps in these area can have several causes and it will depend on the characteristics of the lump and other associated symptoms. Common causes include enlarged lymph nodes that can occur if you have infections from the neck or from the lung and chest area. Sometimes, these lymph nodes can herald more serious conditions such as lung or chest tumors, and even tumors inside the abdomen can present with enlarged lymph nodes in this area. Other possibilities include benign conditions such as lipoma (abnormal fat accumulation), or inflammation of the clavicle and sternum joints. I suggest you have this evaluated and looked at by your doctor.
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