Widespread use of mammography has increased the detection of ductal carcinoma in situ with microinvasion (DCISM) in pathology specimens. Currently there is disagreement regarding the incidence of axillary metastasis from DCISM. The controversy centers on whether complete lymphadenectomy is indicated for axillary staging, given its morbidity and the reportedly minimal rate of axillary involvement in these patients. Intraoperative lymphatic mapping and sentinel lymphadenectomy (SLND) may obviate complete axillary lymph node dissection in selected breast carcinoma patients. In intraoperative lymphatic mapping, isosulfan blue dye is used to demonstrate the course of lymphatic flow from the breast tumor to the first draining or sentinel lymph node. This blue-stained lymph node is selectively excised for pathologic examination; its tumor status is used to predict the tumor status of the other axillary lymph nodes. The authors examined whether SLND would be suitable for staging DCISM.
From February 1992 to January 1997, 14 patients with DCISM underwent intraoperative lymphatic mapping and SLND at the John Wayne Cancer Institute in Santa Monica, California. Clinical and pathologic data were prospectively collected.
Primary DCISM tumors ranged in size from 0.9 to 6.5 cm. Nine patients presented with mammographic abnormalities, two patients presented with Paget's disease and a palpable lesion, and three patients presented with palpable lesions. Two patients (14.3%) had tumor-involved sentinel lymph nodes. One of these patients had two sentinel lymph nodes, both of which contained single cancer cells identified by immunohistochemistry. The other patient had 1 sentinel lymph node, in which a 0.3-cm metastasis was revealed by light microscopy. Completion axillary dissection was performed on both patients and revealed no further tumor positive lymph node metastases.
SLND can detect lymph node micrometastases (tumor deposits <2 mm) in patients with DCISM. The clinical relevance of these micrometastases is unknown, but their existence shows that DCISM can involve the lymph nodes. Cancer 1999;85:2439–43. © 1999 American Cancer Society.