Galectin-3 immunostaining in cytological and histopathological diagnosis of thyroid lesions.
BACKGROUND
Galectin-3 is a human lectin linked to malignant transformation in different organs including thyroid gland. We aimed to evaluate the diagnostic role of galectin-3 in differentiating benign from malignant thyroid lesions in cytological and histological samples.


METHODS
This study included a total of 79 cases; 19 multinodular goiter (MNG), 19 follicular adenoma (FA), 13 follicular carcinoma (FTC) and 28 papillary carcinoma (PTC). Galectin-3 immunostaining was applied on histological sections from all the cases (retrospective analysis) as well as for the available preoperative FNAC (28 cases) (prospective analysis).


RESULTS
Retrospective analysis: The positivity percentage of galectin-3 was 10.5%, 92.3%, 93% for nonmalignant, FTC and PTC respectively. According to H score, glaectin-3 immunostaining was significantly lowered in FA) 1+/-2.8 as compared to papillary (158.5+/-88.6) and follicular carcinoma (150+/-83.9) (p>0.0001). However, there was no statistically significant difference between FTC and PTC (p=0.56) or between classic and follicular variants of PTC (p=0.51). Sensitivity, specificity, positive and negative predictive values for galectin-3 staining were 93%, 89.5%, 90.5% and 92% respectively. Prospective analysis: There were five benign, six malignant and 17 indeterminate cytology cases. Galectin-3 immunostaining was able to detect the benign nature of 11/17 indeterminate cytology. Combination of standard cytological evaluation with galectin-3 immunostaining markedly improved sensitivity (71% versus 85%), specificity (75% versus 94%), positive predictive value (83% versus 92%) negative predictive value (60% versus 87.5%) and diagnostic accuracy (72% versus 90%).


CONCLUSIONS
We suggest Galectin-3 as a supplementary immunostaining in histological diagnosis of difficult thyroid follicular lesions and in preoperative evaluation of indeterminate thyroid cytology to avoid unnecessary aggressive surgical interference in benign lesions.
The Department of Pathology, Faculty of Medicine, Menoufiya University. hayamaiad@yahoo.com
Hayam A
HA
Aiad
Mona A
MA
Kandil
Nancy Y
NY
Asaad
Ahmad M
AM
El-Kased
Sheren F
SF
El-Goday
D000328:Adult; D044963:Biopsy, Fine-Needle; D002291:Carcinoma, Papillary / Q000175:diagnosis; D003581:Cytodiagnosis; D005260:Female; D037502:Galectin 3 / Q000032:analysis*; D006044:Goiter, Nodular / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D013964:Thyroid Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology
D037502:Galectin 3