title: Cytokeratin immunostaining patterns of benign, reactive lymph nodes: applications for the evaluation of sentinel lymph node specimen.
abstract: The use and interpretation of cytokeratin (CK) immunostains of sentinel lymph node specimens for breast carcinoma remain controversial. Variable immunoreactivity with anti-CK antibodies and CK-positive interstitial reticulum cells may complicate interpretation. The authors examined a series of reactive lymph nodes selected from patients without a history of malignancy. To demonstrate potential diagnostic pitfalls, three different CK antibody combinations were studied to characterize the immunostaining patterns. Formalin-fixed sections of lymph nodes were immunostained with a labeled streptavidin-biotin method using a DAKO autostainer. The anti-CK antibody preparations evaluated were AE1/AE3, CAM 5.2, and an in-house-prepared CK cocktail composed of 7 antibodies. The authors observed that up to 10% of cells in benign, reactive lymph nodes may be immunoreactive with anti-CK antibodies. AE1/AE3 stained 2 of 20 cases with rare immunoreactive reticulum cells, whereas CAM 5.2 and the CK cocktail immunostained cells in 85% of cases with reticulum cells in sinuses and the paracortex. Rare positive to 2+ cells were present in a similar distribution with these two antibodies. Careful interpretation of CK immunostaining of sentinel lymph node biopsies is essential, as is awareness of the presence of CK-positive native reticulum cells, to avoid confusion with single cells of metastatic carcinoma.
authors.affiliation: Department of Pathology, Henry Ford Hospital, Detroit, Michigan 48202, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Linden
authors.forename: R J
authors.initials: RJ
authors.lastname: Zarbo
mesh_terms: D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal; D002648:Child; D002675:Child, Preschool; D003951:Diagnostic Errors / Q000517:prevention & control; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000276:immunology / Q000378:metabolism*; D008198:Lymph Nodes / Q000737:chemistry / Q000473:pathology; D008297:Male; D019310:Pseudolymphoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D021701:Sentinel Lymph Node Biopsy / Q000379:methods / Q000592:standards*
chemical_list: D000911:Antibodies, Monoclonal; D007633:Keratins