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Lumps in that area could be a localized collection of fat, a swollen lymph node, or a neurofibroma (localized harmless swelling in a nerve). Generally all these are harmless swellings and can be present for life. However since it is near your breast, please ask your PCP to look at it once. Also check if there are any swollen lymph nodes in the axilla.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!