Immunohistochemistry of thyroid carcinoma--an experience with thyroglobulin and calcitonin

A retrospective immunohistochemical study of 33 cases of primary thyroid carcinomas and 5 cases of metastases to thyroid was carried out. The immunostaining for thyroglobulin and calcitonin was done by peroxidase-anti-peroxidase (PAP) technique. The optimum staining results were obtained by proper standardisation of the staining procedure and reagents. The sections were systematically evaluated for immunostaining intensity and distribution. The observations revealed that thyroglobulin and calcitonin could be useful as sensitive and specific histogenetic markers for follicular and parafollicular cell derived thyroid carcinomas respectively. However, there was no absolute correlation between thyroglobulin positivity and grade of differentiation. The immunostaining could not differentiate follicular adenoma from follicular carcinoma. More extensive study using other markers may be useful for better patient management.