Histologic and ultracytochemical studies on thyroid medullary carcinoma. Diagnostic significance of argyrophil secretory granules

Abstract

Morphological, histochemical, and ultracytochemical characteristics on eight cases of thyroid medullary carcinoma are described. Solid-alveolar, streaming, ribbon, and rosette patterns characterized the histology of thyroid medullary carcinoma. Tumor cells were argyrophilic, and there were scattered numbers of ganglion cell-like tumor cells with well-impregnated dendritic processes. Ultracytochemically, it was demonstrated that the secretory granules of tumor cells contained argyrophil chemical substance closely related to polypeptide hormone (thyrocalcitonin). We consider these morphological and cytochemical characteristics as additional evidence indicating that thyroid medullary carcinoma arises from the parafollicular cells derived from the neural crest. The amount of amyloid showed a close relation to the number of secretory granules. In a case with a small number of secretory granules, amyloid deposition was not demonstrated. We stress the diagnostic significance of argyrophil secretory granules in establishing a diagnosis of thyroid medullary carcinoma, even in cases without amyloid deposits.