Breast malignant, males, children
Breast cancer
Sentinel lymph nodes

Author: Monika Roychowdhury, M.D. (see Authors page)

Revised: 20 October 2016, last major update February 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Sentinel lymph nodes [title]

Cite this page: Sentinel lymph nodes. website. Accessed October 26th, 2016.
Definition / General
  • Sentinel node is first node to which lymphatic drainage and metastasis from breast cancer occurs
  • Usually an axillary node in central group of level I, but may be at level II (behind the pectoralis minor muscle), level III (infraclavicular) or be intramammary, interpectoral (Rotter's) or internal mammary node (Eur J Surg Oncol 2009;35:252)
  • Tumor is more likely at inflow junction of afferent lymphatic vessel (Am J Surg Pathol 2003;27:385)
Clinical Features
  • Sentinel node may have characteristics that prevent further tumor spread up the lymphatic chain (Int Semin Surg Oncol 2006;3:39)
  • Procedure: surgeon injects blue dye or radioactive colloid around tumor, which travels to and identifies the first draining sentinel lymph node; extensive pathologic examination is performed of sentinel node (see below) to look for micrometastases
  • If sentinel node(s) is negative, other nodes are negative in > 95% of cases; axillary recurrence rate is only 0.3% at median 34 months (Eur J Surg Oncol 2008;34:1277)
  • Considered a suitable replacement for axillary dissection for staging / diagnosis in T1 and T2 tumors, with reduced patient morbidity because fewer lymph nodes are removed (Ann Surg OncolM 2008;15:1996); may have a role in microinvasive disease (Breast J 2008;14:335)
  • Intraoperative frozen section (World J Surg Oncol 2008;6:69), intraoperative imprint cytology (Eur J Surg Oncol 2009;35:16) or molecular assays may be useful (J Clin Oncol 2008;26:3338)
  • Frozen section had 60% sensitivity and 100% specificity in one study, with “atypical” cases usually negative on permanent sections (Mod Pathol 2005;18:58); concentrated smear technique is more sensitive than direct smears (Am J Clin Pathol 2004;122:944)
  • High risk (60%) of tumor in nonsentinel nodes if sentinel node has macroscopic tumor (2 mm or more) versus low risk (3%) if microscopic tumor (0.2 to 2 mm, Mod Pathol 2005;18:762)
  • Micrometastases may not affect survival (Ann Oncol 2009;20:41, J Clin Oncol 2009;27:4679) but see J Am Coll Surg 2009;208:333
  • In addition, cohesive cluster of malignant cells, 0.2 mm to 2.0 mm, may indicate significant axillary disease; smaller clusters are highly unlikely to be associated with significant residual metastasis or poor prognosis
  • May be useful even after neoadjuvant [preoperative] chemotherapy (Acad Radiol 2009;16:551)
  • In transit metastasis - metastases in lymph nodes other than sentinel node, that are associated with afferent lymph vessels to the sentinel node but not are typically removed during sentinel node procedure (J Clin Pathol 2008;61:1314)
  • Memorial Sloan-Kettering Cancer Center nomogram is useful to surgeons to predict likelihood of non-sentinel lymph node axillary metastases (Ann Surg Oncol 2003;10:1140, J Am Coll Surg 2009;208:229)
  • Recommendations for handling radioactive specimens at: Am J Surg Pathol 2000;24:1549
  • Pre-operative axillary ultrasound and fine needle aspirate cytology (FNAC) are routine at many breast units, with a sensitivity of 56% (confidence interval: 47 - 64%) and specificity of 90% (84 - 93%) for ultrasound alone, and 76% (61 - 87%) and 100% (65 - 100%) combined with FNAC (Breast 2011 Oct 5 [Epub ahead of print]); its use before sentinel lymph node biopsy significantly increases the identification rate and decreases the false negative rate (J BUON 2011;16:454)

Isolated tumor cells
  • Single cells in lymph nodes interpreted as malignant; clinical significance has not yet been demonstrated
  • Primary tumors associated with sentinel nodes with isolated tumor cells have more lymphovascular invasion and higher proliferative rate than primaries without nodal involvement, but less lymphovascular invasion, lower proliferative rate and smaller tumor size than primary tumors with micro- or macrometastases (Surgery 2008;144:518)
  • May represent benign epithelium or degenerated malignant cells (Am J Surg Pathol 2009;33:106, Hum Pathol 2009;40:778)

Consensus recommendations
False positives with cytokeratin
Case Reports
Clinical Images

Images hosted on other servers:

Blue stained axillary node

Micro Images

Images hosted on other servers:

Isolated tumor cells are AE1 / AE3+

Isolated tumor cells and micrometastasis

False positive cases

Erroneous use of lamda light chain, which stains plasma cells, instead of AE1 / AE3

Sclerosing adenosis, not tumor

Fig 1: micrometastases-H&E
Fig 2: micrometastasis-AE1 / AE3+

Fig 1: negative H&E
Fig 2: AE1 / AE3 demonstrates micrometastasis