Triple-negative breast cancer first discovered through a duodenal metastasis

What happened, in summary

A 57-year-old woman sought repeated care for two months of pain after eating, nausea, poor appetite, and bloating. Treatment for presumed indigestion did not help. She also noticed a painless lump in her right neck. A routine mammogram six months earlier had been normal, and she had no palpable breast or axillary mass.

She was admitted when testing showed severe microcytic anemia with a hemoglobin near 7 g/dL and blood in the stool. CT showed extensive lymph-node enlargement and thickened segments of small bowel. Endoscopy identified a fragile, necrotic mass in the second part of the duodenum. Biopsy showed poorly differentiated ductal carcinoma of breast origin. The cells were CK7-positive, GATA3-positive, and vimentin-positive, while intestinal markers CDX2 and CK20 were negative. Estrogen receptor, progesterone receptor, and HER2 were all negative, confirming triple-negative disease. Repeat mammography and breast ultrasound still showed no primary breast lesion.

She received blood transfusions and palliative radiation to the distal stomach and duodenum, totaling 2000 cGy. Weekly paclitaxel was then started. After the first dose, she returned with breathlessness, abdominal pain and swelling, peripheral edema, acute kidney injury, severe electrolyte abnormalities, and persistent anemia. Imaging showed small-bowel obstruction and a left pleural effusion.

Surgery was not recommended because of her poor overall prognosis. She and her family chose comfort-focused care. She experienced cardiorespiratory arrest and died two days later. The diagnosis occurred only after metastatic disease caused gastrointestinal bleeding and obstruction, despite recent negative breast imaging and no detectable breast mass.