Case Presentation
A 72-year-old Caucasian postmenopausal woman was evaluated for a palpable right axillary mass that she had identified on self-examination approximately two weeks prior to presentation. The mass was non-tender and not associated with nipple discharge or any systemic symptomatology. The patient was G2P2, with menarche at age 10 and menopause at age 50. She reported a family history significant for a diagnosis of breast cancer in her sister at age 41 and niece at age 53. There was no family history of ovarian cancer. Of note, the patient’s sister had negative BRCA testing. Physical examination revealed a slightly mobile mass in the right axilla located about 6 cm below the axillary crease and 1.5 cm anterior to the mid-axillary line. The patient had a thin body habitus, and the right axillary mass was located essentially in the subcutaneous layer of the skin. There was no adenopathy in the right axilla or in the bilateral cervical or supraclavicular regions. A bilateral diagnostic mammogram showed a spiculated mass measuring 0.9 cm in diameter in the extreme axillary tail of the right breast that corresponded with the palpable mass found on physical examination (Figure 1). An ultrasound of the right axilla demonstrated a hypoechoic, irregular mass with spiculated margins measuring 0.9 x 0.7 x 1.3 cm that was surrounded by marked vascularity (Figure 2). No abnormal lymph nodes were identified on mammogram or ultrasound. These findings were assigned a BI-RADS 4 classification.
An ultrasound-guided core needle biopsy revealed a grade 2 invasive lobular carcinoma (ILC) that was ER-positive (95%), PR-negative (0%), and HER2/neu-positive by fluorescence in situ hybridization. A bilateral breast MRI was performed to rule out the presence of any other breast abnormalities. Representative T1 fat saturated post-contrast sagittal and coronal breast MRI images demonstrated an irregular enhancing mass in the right axilla (Figure 3) consistent with biopsy-proven ILC but was otherwise negative. Ultimately, the patient was determined to have a stage IA (cT1cN0) breast cancer.
After consultation with the breast medical oncology team, the patient underwent wide local excision of the right axillary mass with SLN biopsy. One hour prior to surgery, the patient was injected with 400 mCi of technetium-99m (Tc-99m) sulfur colloid. One-third of the dose was injected intra-dermally into the skin overlying the mass, one-third was injected directly into the mass, and the remaining third was injected into the subcutaneous tissue underneath/posterior to the mass. At the time of operation, the right axilla was examined and the position of the mass was noted 6 cm inferior to the axillary crease. The axilla was scanned, and an area of increased counts was identified just superior to the tumor in the mid-axillary line. An elliptical incision was created over the mass and deepened with cautery. The tumor was resected along with an ellipse of overlying skin and a rim of normal adipose tissue measuring approximately 1 cm. Additional shave margins were taken. The posterior border of the tumor consisted of the pectoralis major muscle, the fascia of this muscle having been included in the primary specimen. The axilla was scanned, and an area of increased counts was identified just under the pectoralis minor muscle against the chest wall. The clavipectoral fascia was incised and a 1 cm lymph node was identified and removed. Ex vivo this lymph node had counts over 900. It was sent for frozen section and ultimately came back positive for metastatic lobular carcinoma. The entire axilla was re-scanned and no other areas of tracer uptake were identified. No suspicious lymph nodes were found by palpation or inspection. The decision was made to forego axillary dissection given existing evidence showing that subsequent radiation therapy alone would be sufficient for control of the axilla.(3) Pathologic evaluation of the lymph node revealed macrometastatic carcinoma measuring 7 mm in diameter without extranodal extension. Regarding the primary tumor, pathologic evaluation revealed a grade 2, ER-positive, PR-negative, and HER2/neu-positive ILC measuring 1.6 cm in maximum diameter. Final margins were negative.
The patient tolerated the procedure well with no post-operative complications. She is now disease-free 6 months following surgery. She received six cycles of adjuvant chemotherapy consisting of a regimen of docetaxel, carboplatin, trastuzumab and pertuzumab. This treatment was followed by whole breast radiation therapy and maintenance pertuzumab/trastuzumab.