Could a fat lobule in breast come back as benign breast tissue on core biopsy pathology?

Yes, of course: The breast is made primarily of fat tissue with some connective tissue (and milk glands, of course). Thus a biopsy would more than likely show fat tissue. I hope your biopsy is completely normal! good luck!

Fat lobule in breast: Yes. Breast tissue is composed of functional elements (glands and ducts) as well as structural elements (connective tissue and vessels). The connective tissue (or stroma) in the breast is composed of various proportions of fat and fibrous tissue. A biopsy from an area of the breast where the fatty component predominates but contains glands or ducts is histologically "benign breast tissue", .

Breast biopsy: Fat is a normal benign part of the breast, so a biopsy of the breast could potentially only show fat. However, usually in breast biopsy the tissue Of interest is the fibrous stroma containing the breast lobules and ducts. If a pathology report says 'benign breast tissue' this would generally refer to benign stroma/ducts/lobules, and not just fat.