Diffuse micronodular gastric metastases from invasive lobular breast carcinoma ‒ Characterization of an unusual...

Gastric metastases from breast cancer are uncommon and may mimic primary gastric neoplasia, particularly in invasive lobular carcinoma. We report a 72-year-old woman with previous luminal B/HER2-negative invasive lobular breast carcinoma and nonspecific diffuse gastric uptake on PET-CT. Upper endoscopy with narrow-band imaging and Near Focus revealed innumerable millimetric micronodular foci over preserved mucosa. Histology showed poorly differentiated adenocarcinoma with signet-ring cells, while immunohistochemistry confirmed metastatic lobular breast carcinoma. This case highlights a previously unrecognized diffuse micronodular endoscopic pattern and the importance of targeted biopsies and immunohistochemistry to avoid misdiagnosis.