Mixed medullary-follicular carcinoma of the thyroid gland: A clinicopathologic variant of medullary thyroid carcinoma

Pathology Section, Kanazawa University Hospital, Japan.
Modern Pathology (Impact Factor: 6.36). 07/1996; 9(6):631-5.
Source: PubMed

ABSTRACT A rare case of mixed medullary-follicular carcinoma of the thyroid gland, which occurred in a 44-year-old man, is reported. The thyroid tumor was composed of solid nests of polygonal cells, with an admixture of many evenly distributed thyroid follicles that contained colloid. The lymph node metastases were the same composition as the primary, with follicle formations that contained colloid. Immunohistochemically, in both the primary and metastatic lesions, calcitonin and carcinoembryonic antigen were present in the predominant solid areas of medullary carcinoma, whereas thyroglobulin was demonstrated in the follicular structures. At the ultrastructural level, most of the tumor cells contained numerous neurosecretory granules, but some showed follicular cell differentiation. These findings fulfilled the criteria of mixed medullary-follicular carcinoma of the thyroid according to the World Health Organization classification and also suggested dual neuroendocrine and follicular differentiation of this type of thyroid carcinoma. We reviewed the literature on mixed medullary-follicular carcinoma of the thyroid and concluded that it might constitute another clinicopathologic entity different from conventional medullary thyroid carcinoma; it occurs predominantly in younger males and is associated with a more favorable clinical course than the usual medullary thyroid carcinoma.

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    American Journal Of Pathology 12/1999; 155(5):1413-8. DOI:10.1016/S0002-9440(10)65453-3 · 4.60 Impact Factor
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    ABSTRACT: Mixed medullary-follicular carcinomas (MMFCs) are tumors of the thyroid that display morphological and immunohistochemical features of both medullary and follicular neoplasms. The histogenetic origin and possible molecular mechanisms leading to MMFCs are still unclear. To address these questions, we have isolated the two histological components of 12 MMFCs by (laser-based) microdissection, analyzed them for mutations in the RET proto-oncogene and allelic losses of nine loci on six chromosomes, and studied the clonal composition of MMFCs in female patients. Our results provide strong evidence that the follicular and medullary components in MMFCs are not derived from a single progenitor cell, because the seven tumors amenable for analysis consistently exhibited a different pattern of mutations, allelic losses, and clonal composition. We also demonstrate that follicular structures in MMFCs are often oligo/polyclonal and more frequently exhibit hyperplastic than neoplastic histological features, indicating that at least a subset of MMFCs are composed of a medullary thyroid carcinoma containing hyperplastic follicles.
    American Journal Of Pathology 12/1999; 155(5):1499-509. DOI:10.1016/S0002-9440(10)65465-X · 4.60 Impact Factor
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    ABSTRACT: We report a case of combined "mixed medullary follicular" and "papIlary" carcinoma of the thyroid that occurred in a 44 yr-old Japanese woman. The grossly single 3 cm tumor was histologically composed of both mixed medullary follicular carcinoma and papillary carcinoma, which abutted against each other with a clear border between two components. Immunohistochemically, the component of medullary carcinoma was positive for calcitonin and carcinoembryonic antigen (CEA), and the follicular carcinoma and papillary carcinoma components were positive for thyroglobulin. Lymph node metastasis was also noted. The patient has been alive without recurrence for 20 yr. To the best of our knowledge, this is the first reported case in the literature. We report this unique case of thyroid carcinoma and review related thyroid malignancies.
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