Pure Tubular Carcinoma of the Breast: Is Axillary Staging Necessary?

Pure tubular carcinoma (PTC) is a rare and well-differentiated tumor of the breast with high survival and low local recurrence rate. Sentinel lymph node biopsy (SLNB) is routinely used but still bears 5% risk of lymphedema. This study aims to investigate axillary involvement rate and necessity of axillary staging in clinically early PTCs. Thirty-seven PTCs in 36 patients between 2010 and 2017 were evaluated retrospectively. Histopathological features, sentinel lymph node detection rate, axillary involvement, and adjuvant treatments were recorded. Median pathological tumor size was 8 (3–18) mm. Median follow-up was 58 (21–106) months. Three patients had multi-focal and one patient had multi-centric tumor. While none of the tumors exhibited lymphovascular invasion, all tumors presented ER+ and Her-2 negative. Thirty-three tumors presented PR+. Median Ki-67 was 6% (1–16%). Histologic grade was low except one patient, whereas nuclear grade was low in 12 (32%) patients and intermediate in 25 (68%) patients. SLNB was positive in two patients in whom both were micro-metastases. Thirteen tumors (35%) were found to have a tumor size of ≥ 10 mm, whereas 24 (65%) tumors were found to be < 1 cm. While axillary metastasis was not detected in patients with tumor < 1 cm, axillary involvement ratio was 15% in the patients with tumor PTC ≥ 1 cm. SLNB can be omitted for patients in whom PTC < 1 cm. However, SLNB is still recommended in suspicion of mixed tubular carcinoma or other types of invasive carcinomas, or PTC ≥ 1 cm in diameter.