What happened, in summary

A woman in her early 20s found a tender, mobile lump in the upper part of her left breast. The mass measured about 50 mm and felt rubbery, making a fibroadenoma the leading clinical possibility. Her history included controlled ulcerative colitis and one second-degree relative with breast cancer. Ultrasound was used because of her young age.

The lump was removed by excisional biopsy. Pathology unexpectedly found low-grade ductal carcinoma in situ located within the fibroadenoma. The cancer was non-invasive and confined to the ducts inside the removed lesion.

A multidisciplinary breast team reviewed the findings and concluded that the excision was adequate local treatment. No additional breast surgery, radiation, chemotherapy, or hormone treatment was required.

At her 6-month follow-up, she had no symptoms and no palpable mass in either breast or armpit. Because of her unusually young age, she was referred for inherited-cancer testing. A broad panel, including BRCA1, BRCA2, PALB2, TP53, and several other genes, found no pathogenic variant.

The plan was continued clinical review and annual breast MRI for 5 years because she was too young for routine mammographic surveillance. After that period, she was expected to return to standard breast screening. At the latest assessment, there was no clinical evidence of remaining or recurrent disease.

The unexpected cancer occupied only part of a lesion that otherwise looked and felt benign. Complete removal allowed the team to avoid additional treatment while using MRI for cautious follow-up. Her follow-up plan reflected her young age rather than evidence of ongoing cancer.