Immunohistochemistry of ultimobranchial thyroid carcinomas in seven slaughtered cows and one bull

From ultrasound to microscopy: Actualities in thyroid investigation in cattle

Thyroid ultrasonography examination is widely used in human and small animal medicine. However, it has rarely been applied in cattle. The aim of this study was to determine whether the measurements of the thyroid gland by ultrasound examination correlate to those taken during post-mortem examination. A sample of 22 cows and 23 calves was selected for thyroid gland evaluation. An ultrasound scan was performed ante-mortem, followed by euthanasia (for medical reasons) or slaughtered in the food chain and the dissection of the thyroid gland was therefore performed. Post-mortem, the gland was weighed and its dimensions and volume measured. The volume and weight measurements were compared with the predicted ones on US using the formulas available in the literature. Finally, histological examination was performed on thyroid glands. The dimensions of the thyroid gland measured by ultrasonography were significantly different (p<0.05) from those observed post-mortem, except for lobe lengths in calves (p>0.1). However, in calves, there was no systematic bias between the ultrasound and post-mortem examination of the thyroid gland, which were concordant (with an average error of 18%). Cystic lesions were observed on ultrasound in 9/22 cows and could be found on histological examination in 7 of these. Other lesions, such as follicular hypoplasia and hyperplasia, were seen on histological examination but not on ultrasound. Although the ultrasound measurements did not significantly correlate with those taken post-mortem, this examination may allow to differentiate non-standard thyroids in the case of hyperplastic goiter, as demonstrated in other species. This study also describes and illustrates interesting lesions of the thyroid gland in cattle. These findings are innovative in the description of the use of thyroid ultrasound in cattle, although further studies are needed to allow deeper conclusions.

Ultimobranchial body cyst in an adult horse: clinical, histopathologic, and immunohistochemical features

A 9-y-old Mangalarga Marchador gelding was referred to a veterinary hospital because of a swelling on the upper right side of the neck. Ultrasound examination revealed a multilocular structure adjacent to the thyroid gland with low echogenic content suggestive of fluid. The mass was removed surgically. Histologically, the cystic cavities in the surgical sample were filled with abundant eosinophilic secreta and lined by cuboidal, segmentally ciliated, columnar epithelium with interspersed goblet cells. Segmental crowding of the multilayered lining of the cyst was noted. Immunohistochemistry suggested the presence of both C cells and follicular cells, given the positivity of the immunomarkers calcitonin and TTF-1, respectively. The histogenesis of ultimobranchial cysts is uncertain. Based on clinical, histopathologic, and immunohistochemical identification, the cystic structure in this case is compatible with an ultimobranchial body cyst.

Follicular cell lineage in persistent ultimobranchial remnants of mammals

It has been a subject of much debate whether thyroid follicular cells originate from the ultimobranchial body, in addition to median thyroid primordium. Ultimobranchial remnants are detected in normal dogs, rats, mice, cattle, bison and humans and also in mutant mice such as Eya1 homozygotes, Hox3 paralogs homozygotes, Nkx2.1 heterozygotes and FRS2α^2F/2F. Besides C cells, follicular cell lineages immunoreactive for thyroglobulin are located within these ultimobranchial remnants. In dogs, the C cell complexes, i.e., large cell clusters consisting of C cells and undifferentiated cells, are present together with parathyroid IV and thymus IV in or close to the thyroid lobe. In addition, follicular cells in various stages of differentiation, including follicular cell groups and primitive and minute follicles storing colloid, are intermingled with C cells in some complexes. This review elaborates the transcription factors and signaling molecules involved in folliculogenesis and it is supposed why the follicular cells in the ultimobranchial remnants are sustained in immature stages. Pax8, a transcription factor crucial for the development of follicular cells, is expressed in the fourth pharyngeal pouch and the ultimobranchial body in human embryos. Pax8 expression is also detected in the ultimobranchial remnants of Eya1 and Hes1 null mutant mice. To determine whether the C cells and follicular cells in the ultimobranchial remnants consist of dual lineage cells or are derived from the common precursor, the changes of undifferentiated cells in dog C cell complexes are examined after chronically induced hypercalcemia or antithyroid drug treatment.

HISTOPATHOLOGIC CHARACTERISTICS OF THYROID GLAND NEOPLASMS IN THOMSON'S GAZELLES ( EUDORCUS THOMSONII)

Published reports of neoplasms in Thomson's gazelles ( Eudorcas thomsonii) are very rare, but thyroid tumors were the most common neoplasm of this species, accounting for 12% of reported pathologies in a 1998-2012 retrospective study of cases submitted for histologic review of grossly enlarged thyroid glands. This report describes the histological and immunohistochemical characteristics of thyroid neoplasms in 10 Thomson's gazelles from five different zoological collections. Neoplasms were submitted as biopsies from six gazelles or collected during necropsy from four gazelles. The most common clinical findings included a palpable mass on the ventral neck and progressive weight loss. Radiographic mineral density was detected in one of the neoplastic masses. Histologically, the neoplasms were classified as microfollicular thyroid adenoma ( n = 2), solid thyroid adenoma ( n = 2), papillary thyroid adenoma ( n = 1), and solid thyroid carcinoma ( n = 5). Neoplastic cells in all 10 neoplasms were positive for thyroid transcription factor 1 and thyroglobulin, but negative for calcitonin. While five cases had histologic features of malignancy, there was no evidence of metastatic disease either clinically (biopsies) or on necropsy. Numerous concurrent diseases, including cardiomyopathies and nephropathies, were present and led to choice for euthanasia in several cases.

On the Origin of Cells and Derivation of Thyroid Cancer: C Cell Story Revisited

We will highlight and put into perspective new lineage tracing data from genetic studies in mice indicating that the genuine progenitors to C cells arise in the endoderm germ layer. This overturns the current concept of a neural crest origin of thyroid C cells referred to in every textbook and dedicated paper to this very day. As will become apparent, except for a single experiment, the neural crest theory has little or no support when the evolution and development of calcitonin-producing cells in the entire chordate family are considered. Instead, a unifying origin of all cells of the ultimobranchial bodies reopens questions on the histogenesis of certain thyroid pathologies previously difficult to explain. On this aspect, medullary thyroid cancer shows a stronger connection to gut neuroendocrine tumours than previously recognized. It is envisaged that novel factors implicated in C cell-derived tumour growth and progression will be discovered as the mechanisms that regulate lineage expansion of embryonic C cell precursors from pharyngeal endoderm are uncovered. We will not discuss why C cells go to the bother of burying themselves in the thyroid - this remains a mystery.

Tumor-in-Tumor of the Thyroid With Basaloid Differentiation: A Lesion With a Solid Cell Nest Neoplastic Component?

This study describes an encapsulated thyroid tumor having 3 different concentric appearances in a 70-year-old man. The most peripheral neoplasm showed features of a microfollicular adenoma; the intermediate lesion displayed typical features of the follicular variant of papillary thyroid carcinoma (FVPTC); and the main, central neoplasm, showed a basaloid configuration. At variance with the other neoplasms, the latter component exhibited high mitotic activity. Necrosis, angio-invasion, or capsular invasions were not observed. The centrally located neoplasm was immunoreactive for several cytokeratins, p63, carcinoembryonic antigen, and galectin-3, and negative for thyroid transcription factor 1, thyroglobulin, calcitonin, CD5, and CK20, featuring a phenotype similar to that of thyroid solid cell nests. A N-RAS mutation was found both in the basaloid and in the FVPTC components. The clinicopathological and immunohistochemical data ruled out the alternative possibilities of intrathyroidal metastasis and tumor from ectopic (thymic, parathyroid, or salivary gland) tissues.