I am sorry to hear that you are dealing with this issue. It sounds like you are being evaluated for potential breast cancer, and this can be a very stressful time. Make sure to communicate closely with your doctor
to get your questions answered as you proceed.
There are many reasons that a breast biopsy could be inconclusive. This could be because the amount of tissue that was obtained was not sufficient to reach a conclusion (for example, if you had a needle biopsy, this can sometimes happen). Alternatively, it could be because the tissue had some abnormalities or irregularities in it that were of unclear significance.
Your doctor will work closely with the pathologist
who examined the biopsy sample and also potentially with a surgeon
to determine what the next step is. Sometimes unclear biopsy results can be sorted out by performing additional analyses of the sample. Sometimes, a period of observation of the breast lump may be necessary, and sometimes an additional biopsy may be required.
Your doctor will be able to work with you through these possibilities and will make recommendation to you on how next to proceed with the workup. Good luck.