Interpretive disparity among pathologists in breast sentinel lymph node evaluation.
BACKGROUND
Immunohistochemical staining on breast sentinel lymph nodes (SLN) is controversial.


METHODS
Twenty-five SLN cases were reviewed by 10 pathologists (three academic, seven private) including 5 negative by both hematoxylin and eosin (H&E) and immunohistochemistry, 11 micrometastases (<2 mm) negative by H&E but positive by immunohistochemistry, and 8 micrometastases and 1 macrometastasis (>2 mm) positive for both H&E and immunohistochemistry. Answers included "positive," "negative," and "indeterminate" for each slide.


RESULTS
The mean number of incorrect responses was 6.6 for immunohistochemistry and 5 for H&E. Twelve percent of cases were correct by all 10 pathologists; 80% of positive IHC cases had at least one pathologist score it incorrectly. As tumor cells decrease in number, incorrect responses increase. When tumor cells numbered less than 10, more than 30% of pathologists answered incorrectly.


CONCLUSIONS
As tumor cells decrease in number pathologists' ability to recognize them decreases. We propose adding "indeterminate" to "positive" and "negative" when tumor cells number less than 10.
Roberts
Cory A
CA
Department of Pathology, St Paul University Hospital and University of Texas Southwestern Medical Center, Dallas, TX, USA. croberts@propathlab.com
Beitsch
Peter D
PD
Litz
Craig E
CE
Hilton
D Sue
DS
Ewing
Gene E
GE
Clifford
Edward
E
Taylor
Walton
W
Hapke
Marc R
MR
Babaian
Armineh
A
Khalid
Imrana
I
Hall
Joe D
JD
Lindberg
Guy
G
Molberg
Kyle
K
Saboorian
Hossein
H
D001943:Breast Neoplasms / Q000473:pathology*; D004396:Coloring Agents; D003951:Diagnostic Errors; D004801:Eosine Yellowish-(YS); D005260:Female; D006416:Hematoxylin; D006651:Histocytochemistry; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis / Q000175:diagnosis; D015588:Observer Variation; D010338:Pathology, Clinical; D015203:Reproducibility of Results; D021701:Sentinel Lymph Node Biopsy
D004396:Coloring Agents; D004801:Eosine Yellowish-(YS); D006416:Hematoxylin