Sentinel lymph nodes

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, PathologyOutlines.com, Inc.

PubMed Search: Sentinel lymph nodes [title]

Table of Contents

Cite this page: Sentinel lymph nodes. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastmalignantsentinel.html. Accessed July 14th, 2017.

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

References: Hum Pathol 2002;33:579
Submit entire node unless gross tumor
Slice large nodes into 3 - 4 mm thick sections and submit all
Other possible protocols if examination of initial H&E stained section does not reveal metastases:
- Obtain 2 additional hematoxylin and eosin-stained sections and one pancytokeratin (AE1-AE3) stained section (Am J Surg Pathol 2002;26:377)
- Obtain 3 additional H&E stained sections (no IHC since occult metastases have minimal predictive value, Mod Pathol 2002;15:641), or:
- Cut into 2 mm slices, obtain 5 levels for each slice - 2 H&E, 3 AE1 - AE3 (Arch Pathol Lab Med 2003;127:701, Arch Pathol Lab Med 2009;133:1437)
- Complete sectioning through block detects additional micrometastases, but raises cost effectiveness concerns (Am J Surg Pathol 2009;33:1583)
Note: AE1 - AE3 is better than CAM 5.2 since less staining of reticulum cells (Arch Pathol Lab Med 2000;124:1310)

False positives with cytokeratin

Benign epithelial cells are associated with pre-sentinel biopsy breast massage (Am J Surg Pathol 2004;28:1641)
Benign glandular inclusions (Am J Clin Pathol 2008;130:21)
Ectopic breast tissue (Am J Surg Pathol 2003;27:513)
Megakaryocytes (Arch Pathol Lab Med 2002;126:618, image)
Mesothelial cell inclusions
Nevus cells (Eur J Dermatol 2008;18:586)
Reticulum cells may be AE3+ (Arch Pathol Lab Med 2002;126:248, image), less of a problem with AE1-AE3)
Sclerosing adenosis (Arch Pathol Lab Med 2008;132:1439)
Wrong antibody (Arch Pathol Lab Med 2001;125:1497)

Case reports

40 year old woman with micro-invasion Level III sentinel node (World J Surg Oncol 2006;4:31)
45 year old woman with distinct populations of infiltrating ductal carcinoma and lobular carcinoma in both breast and sentinel lymph node (Arch Pathol Lab Med 2004;128:365)

Clinical images

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