Gastrointestinal metastasis from invasive lobular carcinoma following breast cancer treatment: A case report

Figure 1 Histopathology and immunohistochemistry findings. A: Biopsy specimens showing diffuse proliferation of poorly differentiated carcinoma cells in the gastric mucosa [hematoxylin and eosin (HE) staining, 200 ×]; B: Biopsy specimens showing diffuse proliferation of poorly differentiated carcinoma cells in the colonic lamina propria (HE staining, 200 ×); C: Gastric immunohistochemical analysis reveals diffuse expression of GATA-binding protein 3 [immunohistochemistry (IHC) for GATA-3, 200 ×]; D: Gastric immunohistochemical analysis reveals diffuse expression of progesterone receptor(IHC for progesterone receptor, 200 ×); E: Gastric immunohistochemical analysis reveals strong immunoreactivity for estrogen receptor (ER) in about 90% of the neoplastic cells (IHC for ER, 200 ×); F: Gastric immunohistochemical analysis reveals absence of E-cadherin expression (IHC for E-cadherin, 200 ×); G: Human epidermal growth factor receptor 2 (HER2) is faintly stained on the cell membranes of some gastric tumors (IHC for HER2, 200 ×); H: Immunohistochemical staining of colonic lesions shows diffuse expression of GATA-3 (IHC for GATA-3, 100 ×); I: Immunohistochemical staining of colonic lesions shows strong immunoreactivity for ER (IHC for ER, 200 ×); J: Immunohistochemical staining of colonic lesions shows absence of E-cadherin expression (IHC for E-cadherin, 200 ×).

Figure 2 Endoscopic images of gastric and rectum lesions. A and B: Endoscopic views of gastric antrum showing multiple crater-like ulcers; C-G: Endoscopic views of rectum showing multiple crater-like ulcers; H and I: Magnified narrow-band images of the lesions showing abnormal microvessels.

Figure 3 Endoscopic images of gastric and rectum lesions after four months of combination therapy with letrozole and palbociclib. A and B: The gastric mucosa exhibits scattered congestive and erosive lesions, with slightly depressed surfaces covered by small amounts of brownish blood crust; C and D: Multiple patchy erosions are noted in the rectosigmoid junction and rectal mucosa.

Figure 4 Endoscopic images of upper and lower gastrointestinal tract one and a half years after the detection of gastrointestinal lesions. A and B: Scattered patchy areas of mucosal hyperplasia are observed in the gastric mucosa, accompanied by focal erosive changes; C and D: The intestinal mucosa appears normal without evidence of pathological lesions.