What happened, in summary

A woman in her 80s with mild dementia noticed a lump in the outer part of her right breast that had been present for about 3 months. The 20 mm mass felt firm but was not painful, red, or inflamed. Ultrasound initially showed a mainly cystic lesion without a clear solid component.

A core biopsy obtained mostly dead, infarcted tissue and did not provide a definite diagnosis. Surgical excision was recommended, but she declined. Three months later, when the mass had become smaller, she agreed to an ultrasound-guided vacuum-assisted biopsy excision.

This larger tissue sample found a 3 mm area of grade 3 invasive ductal carcinoma within extensively infarcted breast tissue. The cancer was estrogen receptor-positive. HER2 testing was equivocal, but confirmatory FISH testing was not performed. The amount of viable cancer was small, but the diagnosis was invasive breast cancer rather than a benign cyst.

She again declined definitive breast surgery. Instead, she chose hormone treatment. Letrozole was started and was later changed to tamoxifen because osteoporosis made continued aromatase-inhibitor treatment less suitable.

At 1.5 years of clinical follow-up, there was no evidence of a remaining breast mass. A formal stage was not assigned, but she continued to respond to endocrine treatment without a clinically detectable residual tumor.

The first core biopsy sampled mainly infarcted tissue and therefore did not provide a definite diagnosis. The larger vacuum-assisted sample was essential because only a very small focus of living cancer remained.