By John Otrompke
CHICAGO -- November 10, 2009 -- Galectin-3, an immunohistochemical marker, distinguishes between malignant and benign follicular-shaped thyroid lesions with 92.6% accuracy, but it should still be used in conjunction with a second marker, HBME-1, researchers stated here at the American Society for Clinical Pathology (ASCP) 2009 Annual Meeting.
The purpose of galectin-3 is to arrange relationships with neighbouring cells, while HBME-1 was originally discovered in the lining of the chest wall, and reacts to mesothelioma cells. Ret oncoprotein, another marker tested, is involved in the development of papillary carcinoma.
"Together the panel showed a sensitivity of 90.7%, which means that, surprisingly, galectin by itself performed a little bit better than using both, but we still recommend using both of them because neither one is absolute by itself, and sometimes there are technical issues with the slide," said Husain Saleh, MD, Department of Pathology, Wayne State University School of Medicine, and Sinai Grace Hospital, Detroit, Michigan, on November 4.
Most thyroid nodules are benign, but 10% of them are malignant, according to Dr. Saleh. "Both malignant nodules, and benign ones such as follicular adenomas and adenomatoid nodules, can have a similar architectural appearance," he said. "This is a very challenging area for pathologists. That's why there is continuous research going on in an attempt to identify some ancillary markers that can distinguish between and separate these 3 entities."
The different cells require different treatment approaches, he added. Benign nodules can be treated with iodine, for example, while the malignant ones need to be excised immediately.
For the study, researchers tested 44 benign lesions (including 37 hyperplastic/cellular nodules and 7 follicular adenomas) and 27 malignant tumours (including 6 follicular carcinomas, 19 classic papillary carcinomas, and 2 follicular variants of papillary carcinoma).
Papillary carcinoma, which is very malignant, is the most common form of thyroid cancer, while the more benign adenomatoid nodules are not a tumour at all, according to Dr. Saleh.
The other markers tested in the study did not do as well as galectin-3 and HBME-1. Ret, for example, correctly identified 85% of malignant lesions (23 of 27) and 32% of the benign lesions (14 of 44). Another marker, CK19, correctly identified 85% of the malignant lesions (23 of 27) and 30% of the benign ones (13 of 44).
[Presentation title: Differential Expression of Galectin-3, CK19, HBME1, and Ret Oncoprotein in the Diagnosis of Follicular-Patterned Thyroid Lesions by Fine-Needle Aspiration Biopsy. Abstract 22]
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