EJMS

Abstract

Background: Some of the nuclear features of follicular variant of papillary carcinoma (FVPC) may not be clear and misdiagnosis with other follicular lesions especially follicular adenoma and carcinoma may occur. Aim: The aim of this work is to assess the expression of both HBME-1 and CK19 in these lesions in an attempt to stand on the best immunohistochemical markers for the accurate diagnosis and so avoid the possible inaccuracy in diagnosis of these lesions. Material and methods: The present study was done on 43 cases of previously diagnosed as FVPC, FC, and FA. Hematoxylin-eosin stain was performed for tumor diagnosis and histologic types. Immunohistochemical stains for HBME-1 and CK 19 were performed on 4-μm-thick paraffin sections taken on poly-L-lysine-coated slides. The degree of reactivity was considered as follow; 0= no reactivity at all and positive staining scored as: 1= less than 10%, 2=11 to 50%, and 3=more than 50% tumor cells stained positive. Results: All 43 cases are reexamined by H&E stain by two pathologists and the results were as follow 20 cases were PC , of these 12 cases were FVPC, 12 cases were FA, 11 cases were FC. As regard HMBE-1 immunostaining, HMBE-1 was negative in 10 cases (83.3%) of follicular adenoma and mildly positive (grade 1) in about (16.7%), moderately and strongly positive in about 75% of cases of PC (of these 8 cases out of 12 FVPC were positive) and 25% were negative, in cases of FC, 45.4 % of cases were positive and 54.6% were negative. On the other hand, CK 19 was found mildly positive in 1 cases of follicular adenoma (8.3%) and the remaining 92.7% were negative, in cases of PC 80% of cases of papillary carcinoma showed positive staining, and 20% demonstrate negative results of these cases, all FVPC showed positive results and, the immunoreactivity was ranged from focal to diffuse moderate to strong cytoplasmic reactivity. All cases of follicular carcinoma showed negative CK 19 immunostaing. Conclusion: Both markers may be more useful if they have been used as a complementary for each other but utilization of CK 19 alone is of great value for evaluating the follicular thyroid lesions.