Axillary fat metastasis in breast cancer: A case report

Abstract

Metastasis remains the primary cause of mortality for patients with breast cancer. Breast cancer metastasis primarily occurs through direct infiltration, the lymphatic system and hematogenous spread, with the axillary lymph nodes being the most common metastatic sites, followed by the lungs, bones, liver and brain. However, metastasis to adipose tissue in malignant tumors is exceedingly rare. The present case report comprehensively describes the clinical diagnosis and treatment of a 54-year-old woman with a malignant tumor in the left breast that metastasized to the left axillary fat tissue. Furthermore, a discussion of relevant studies on fat metastasis in malignant tumors is presented.

Keywords: axillary fat; breast cancer; fat microenvironment; metastasis.

Figure 1.

Preoperative imaging data of the patient. (A) Mammography. (B) T1- and (C) T2-weighted breast magnetic resonance imaging. (D) Actually color-Doppler ultrasound and (E) contrast-enhanced breast ultrasound of the patient before surgical treatment. White arrows indicate the location of the tumor. CEUS, contrast-enhanced ultrasound; WI, weight imaging.

Figure 2.

Pathological examination results of the left breast lumpectomy specimen. H&E staining at (A) ×100 magnification (scale bar, 50 µm) and (B) ×400 magnification (scale bar, 20 µm). Black arrows indicate tumor cells. IHC for (C) Ki-67 (magnification, ×100; scale bar, 50 µm), (D) ER (magnification, ×100; scale bar, 50 µm), (E) PR (magnification, ×100; scale bar, 50 µm) and (F) HER2 (magnification, ×100; scale bar, 50 µm) in the left breast lumpectomy specimen. IHC, immunohistochemistry; ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor 2.

Figure 3.

Pathological examination results of the left axillary sentinel lymph nodes and fatty tissue. (A) H&E staining at ×20 magnification (scale bar, 200 µm). IHC for (B) PCK (magnification, ×40; scale bar, 200 µm), (C) Ki-67 (magnification, ×100; scale bar, 50 µm), (D) ER (magnification, ×100; scale bar, 50 µm), (E) PR (magnification, ×100; scale bar, 50 µm) and (F) HER2 (magnification, ×100; scale bar, 50 µm) in the left axillary sentinel lymph nodes and fatty tissue. The yellow dashed box indicates the left axillary sentinel lymph node and the red dashed box indicates the adipose tissue adjacent to the left axillary sentinel lymph node (metastatic lesion). Black arrows indicate tumor cells. PCK, cytokeratin; ER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor 2.

Figure 4.

Radiological follow-up imaging of the patient. (A) Chest computed tomography showing no evidence of pulmonary or mediastinal metastasis. (B) Breast ultrasonography revealing postoperative changes in the left breast, with no signs of local recurrence. (C) Abdominal ultrasonography demonstrating no hepatic or peritoneal abnormalities.