What happened, in summary

A 59-year-old woman noticed a lump in the lower outer area of her left breast. Imaging showed a suspicious mass measuring roughly 2 to 2.5 cm, and needle sampling found tumor cells. She underwent surgical excision of the breast lesion together with a sentinel lymph node biopsy.

Final pathology identified a rare breast cancer called tall cell carcinoma with reversed polarity. The tumor measured 2.2 cm, and all 5 sampled sentinel lymph nodes were negative. Testing showed HER2 negativity with weak estrogen- and progesterone-receptor expression. Molecular testing also found IDH2 and PIK3CA mutations, findings that supported the diagnosis of this uncommon tumor type.

Because the tumor was considered relatively indolent and the lymph nodes were negative, she did not receive chemotherapy, radiation, or hormone therapy after surgery. At 6 months of follow-up, she was alive and disease-free.