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: 6.19).
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.
Available from: Negar Azarpira
- "Metastatic foci of either PTC or MTC were detected in few patients [4,6,7]. These lymph node metastases show pure tumor cell populations of one or two components or an admixture of both components within the same lymph node [9,17]. Distant metastases were described mostly in the mediastinum, lung, liver, and bone . "
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ABSTRACT: Papillary thyroid carcinoma and medullary thyroid carcinoma are two different thyroid neoplasia. The simultaneous occurrence of medullary thyroid carcinoma and papillary thyroid carcinoma as a collison tumor with metastases from both lesions in the regional lymph nodes is a rare phenomenon.
A 32-year-old Iranian man presented with a fixed anterior neck mass. Ultrasonography revealed two separate thyroid nodules as well as a suspicious neck mass that appeared to be a metastatic lesion. The results of thyroid function tests were normal, but the preoperative calcitonin serum value was elevated. Our patient underwent a total thyroidectomy with neck exploration. Two separate and ill-defined solid lesions grossly in the right lobe were noticed. Histological and immunohistochemical studies of these lesions suggested the presence of medullary thyroid carcinoma and papillary thyroid carcinoma. The lymph nodes isolated from a neck dissection specimen showed metastases from both lesions.
The concomitant occurrence of papillary thyroid carcinoma and medullary thyroid carcinoma and the exact diagnosis of this uncommon event are important. The treatment strategy should be reconsidered in such cases, and genetic screening to exclude multiple endocrine neoplasia 2 syndromes should be performed. For papillary thyroid carcinoma, radioiodine therapy and thyroid-stimulating hormone suppressive therapy are performed. However, the treatment of medullary thyroid carcinoma is mostly radical surgery with no effective adjuvant therapy.
Available from: Xavier Matias-Guiu
Available from: Paul Komminoth
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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.
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