[Mixed medullary and follicular carcinoma of the thyroid: report of one case]. / Carcinoma misto midollare e follicolare della tiroide: case report.

INTRODUCTION: Mixed medullary-follicular carcinoma of the thyroid with pleomorphic pattern is an uncommon malignant epithelial tumor characterized by clinical and immunohistochemical features of both follicular and parafollicular thyroidal C cells. MATERIAL AND METHODS: We describe a rare case of this type of tumor observed in a 56 year old woman, undergone total thyroidectomy for suspected thyroid carcinoma, without lymph node metastasis. Preoperative basal calcitonin levels were in the limits, while thyroglobulin resulted increased. Presence of the latter suggests a potential usefulness of radioiodine therapy as an additional therapeutic tool for this type of tumor. RESULTS: Histological and immunohistochemical findings were surprising showing characteristic patterns and thyroglobulin and calcitonin positivity. After postoperative diagnosis the patient undergone specific endocrine and scintigraphic tests. CONCLUSIONS: Early diagnosis of a mixed medullary-follicular thyroid carcinoma is essential, considering its special therapy and negative prognosis. In fact it constitutes another clinicopathologic entity, different from typical medullary thyroid carcinoma and it's associated with a more favourable clinical course than the former. A precise diagnosis of this uncommon variety of medullary carcinoma of the thyroid is fundamental for an accurate treatment of the patient, but also for familiar genetic screening excluding MEN II syndromes. A radical surgical therapy plays a key-role for the treatment and the follow-up of this rare tumoral entity.

Insulin-like growth factor-1 and insulin-like growth factor receptor in thyroid tissues of patients with Graves' disease.

Growth factors are frequently involved in the regulation of mitosis and differentiation of several cell types and insulin-like growth factor-1 (IGF-1) is actively involved in the thyroid stimulating hormone-mediated proliferation of thyrocytes. In view of the pivotal role of IGF-1 in thyrocyte proliferation and of the still unsettled role of this growth factor in the pathogenesis of hyperplastic thyroid lesions, we investigated the expression of IGF-1 and of its corresponding receptor, by means of immunohistochemistry, in the surgical specimens obtained from six patients with Graves' disease. Moreover, IGF-1 mRNA expression was analysed in one such case by means of Northern hybridisation. All samples showed consistent intracytoplasmic immunoreactivity for both IGF-1 and IGF-1 receptor; the vast majority of hyperplastic thyrocytes were strongly decorated by the two antibodies used in this study whereas stromal cells displayed IGF-1 immunoreactivity only. IGF-1 mRNA was markedly overexpressed in Graves' disease in comparison with normal thyroid tissues. The results of this study suggest that IGF-1 and IGF-1 receptor may be actively involved in the pathogenesis of Graves' disease; furthermore, IGF-1 and IGF-1 receptor apparently act by different mechanisms (paracrine vs. autocrine) as suggested by their differential expression in epithelial and stromal cells.