Fibroadenoma at 20x Magnification
Fibroadenomas, which are generally firm, smooth, and round, can be readily moved under the skin and are often described as feeling similar to marbles. Typically the masses measure from 1 to 3 centimeters in size, but occasionally they may grow much larger, in which case they are termed giant fibroadenomas. Fibroadenomas, which arise from the intralobular stroma, are solid and consist of a combination of glandular and fibrous tissues. The tumors are usually painless and present no symptoms, typically being discovered by young women only due to self-examination. In older women, fibroadenomas are often less palpable and may first be discovered during a routine mammogram.