During self-examination a 22-year-old patient revealed a mammary tumour. Palpation revealed a firm, painless, freely mobile formation up to 2 cm, peripheral lymph nodes were not changed. USI results: in the superior external quadrant of the right mammary gland there was a big formation of increased echogenicity, sized 18x17 mm. The patient was provisionally diagnosed with fibroadenoma. What is a doctor's further tactics?