Immunocytochemical detection of Ki-67 in Diff-Quik-stained cytological smears of canine mammary gland tumours.
OBJECTIVE
To investigate whether Diff-Quik stained fine needle aspirate smears can be used to evaluate Ki-67 expression by immunocytochemistry.


METHODS
Both cytological and histological samples were obtained from 24 dogs with spontaneously developed mammary gland tumours. The cytological and histological specimens were examined by Diff-Quik and H&E stains, respectively. After examination, both samples were immunostained using the same Ki-67 antibody. The % Ki-67 values were calculated based on the percentage of positively stained tumour cells per 500 and 1000 tumour cells in cytology and histology specimens, respectively.


RESULTS
Ki-67 staining was successful in 17/24 smears (71%) and 19/23 sections (83%). The correlation coefficient between the percentage of Ki-67-positive cells in cytological smears and in the histological sections was 0.677 (P < 0.01). These values were significantly different between histologically benign and malignant tumour groups both in cytology and histology samples (P < 0.001). The threshold value of the percentage of Ki-67-positive cells for distinguishing benign from malignant tumours was set at 4.85% with 90.9% sensitivity and 92.3% specificity by Receiver Operating Characteristic (ROC) curve using histopathology as the gold standard.


CONCLUSIONS
Diff-Quik-stained cytology smears can be used to detect the presence of Ki-67 antigen when histology sections are not available.
Choi
U S
US
Department of Veterinary Clinical Pathology, College of Veterinary Medicine, Chonbuk National University, Duckjin Dong, Duckjin gu, Jeonju, South Korea. uschoi@jnbu.ac.kr
Kim
D Y
DY
D000818:Animals; D001399:Azure Stains / Q000737:chemistry*; D044963:Biopsy, Fine-Needle; D004285:Dogs; D005260:Female; D007150:Immunohistochemistry / Q000379:methods; D019394:Ki-67 Antigen / Q000032:analysis*; D015674:Mammary Neoplasms, Animal / Q000175:diagnosis* / Q000473:pathology; D008751:Methylene Blue / Q000737:chemistry*; D013194:Staining and Labeling / Q000379:methods; D014966:Xanthenes / Q000737:chemistry*
D001399:Azure Stains; C067461:Diff Quik; D019394:Ki-67 Antigen; D014966:Xanthenes; D008751:Methylene Blue