Differential diagnosis of thyroid tumours. An immunocytochemical study.

Fifty-seven patients with thyroid tumours, 11 malignant lymphomas, 12 follicular, eight papillary and 26 medullary carcinomas, were studied. HE stained sections and immunocytochemical reactions with mono- and polyclonal antibodies were evaluated. The usefulness of thyroglobulin staining in differential diagnosis of infiltrations and metastases was stressed. The group of medullary carcinomas was morphologically polymorphic and presented unexpected patterns of immunoreactivity. Recent embryological findings were discussed providing better understanding of this group of carcinomas. The presence of thyroglobulin, along with other markers in areas of medullary carcinoma in polymorphic tumours, and the presence of neuro-endocrine markers in areas of follicular or papillary differentiation seem to be concordant with the theory of a pluripotential cell, derived from neural crest and capable of differentiation into a variety of forms.