Hi thanks for your question.
The swelling in the breast could be benign tumor
of breast called as fibroadenoma
.The second possibity could be anther sebious cyst
in breast .Your not clear in your question,where from biopsy
was taken ? If biopsy was taken from same swelling, there is no need to repeat but if removed sebious cyst was sent for biopsy then you have to repeat biopsy.
Hope this answers your question.