Ectopic lingual thyroid tissue in a cat

Proceedings of the 2018 National Toxicology Program Satellite Symposium

The 2018 annual National Toxicology Program Satellite Symposium, entitled "Pathology Potpourri," was held in Indianapolis, Indiana, at the Society of Toxicologic Pathology's 37th annual meeting. The goal of this symposium was to present and discuss challenging diagnostic pathology and/or nomenclature issues. This article presents summaries of the speakers' talks along with select images that were used by the audience for voting and discussion. Various lesions and other topics covered during the symposium included seminiferous tubule dysgenesis in rats, ameloblast and odontoblast degeneration/necrosis in a Sprague Dawley rat, intestinal leiomyositis in a beagle dog, gallbladder mucinous hyperplasia, focus of hepatocellular alteration and bile duct alteration in otters, renal tubule cytoplasmic vacuolation with basophilic granules in mice treated swith antisense oligonucleotide therapy, a uterine choriocarcinoma in a rhesus macaque, and rete ovarii proliferative ovarian lesions in various aged rat strains. One particularly provocative lesion was a malignant neoplastic proliferation in the renal pelvic region of a cynomolgus macaque from a 21-day study. Additional challenging lesions included thyroid proliferative lesions in zebra fish and gross findings in fish larvae during routine chemical screening. The Rabbit and Minipig International Harmonization of Nomenclature and Diagnostic Criteria Organ Working Groups also presented a series of challenging lesions.

Gastric duplication: proventricular cystic choristoma on the spleen of a broiler chicken

Gastric duplication (choristoma) is a very rare anomaly in both humans and other animal species. We report herein a case of proventricular cystic choristoma in a 62-day-old broiler chicken. The broiler chicken was brought from the slaughterhouse to our laboratory after a pale-brown cystic structure closely attached to a thin, compressed spleen was identified. On necropsy, the cystic structure showed a clear mucinous fluid. Histopathologically, the cystic structure was lined by proventricular mucosa presenting in folds and sulci. Submucosal proventricular glands, consisting of secretory units and collecting tubules, occupied parts of the choristomal wall. The gastric mucosa lining the choristomal wall stained positive with periodic acid-Schiff stain, stained negative with Alcian blue staining, and showed a thin layer of smooth muscle fibers and a thick connective tissue layer with Masson trichrome. Ectopic pancreas was noticed attached to the wall of the choristoma. To the best of our knowledge, this represents the first report of choristoma in an avian species.

Clinical features and treatment outcomes of 41 dogs with sublingual ectopic thyroid neoplasia

Background

Thyroid neoplasia is common in dogs, but there are few reports of dogs with ectopic, sublingual thyroid tumors.

Objectives

To describe clinical features and outcomes of dogs with ectopic, sublingual thyroid neoplasia.

Animals

Five hundred and forty‐four dogs with thyroid neoplasia.

Methods

This retrospective study reviewed the medical records of dogs referred for thyroid neoplasia between 1995 and 2013. Data extracted included signalment, extent of thyroid disease (eutopic or ectopic; metastasis), serum thyroxine (T₄) concentration, treatment, and survival.

Results

Of 544 dogs with thyroid neoplasia, 41 (7.5%) dogs had ectopic sublingual thyroid tumors. The clinical features of these 41 dogs were similar to the cohort group of 503 dogs with eutopic or ectopic mediastinal thyroid tumors, but dogs with sublingual tumors were younger and less likely to have metastatic disease (15% versus 30%, P < .05). Of the 41 dogs, 28 received treatment: 21 with surgery (which included partial hyoidectomy in 13), 7 with radioiodine alone, and 13 with surgery followed by administration of radioiodine. Overall median survival was 562 days (range, 1‐1,850 days).

Conclusions and Clinical Importance

When compared with eutopic thyroid carcinomas, ectopic sublingual thyroid tumors generally have a less aggressive biologic behavior. Many dogs have prolonged survival, even without treatment, although death because of local tumor invasiveness or metastasis can develop in some dogs. Surgical thyroidectomy, including partial hyoidectomy, is generally effective for control of local disease. Administration of radioiodine, alone or in combination with surgical treatment, is recommended for multifocal disease or metastasis.

Computed tomographic features of basihyoid ectopic thyroid carcinoma in dogs

Eight dogs with a firm, nonpainful swelling in the ventral laryngeal region and with a final diagnosis of ectopic thyroid carcinoma were investigated by Computed Tomography (CT) at six different institutions. Computed Tomography findings were reviewed, focusing on lesion volume, shape, margins, relationship with surrounding structures and adjacent vessels, attenuation characteristics, and presence of metastases. Ectopic thyroid carcinomas were seen as oval-to-bilobed masses centered on the basihyoid bone with associated bone lysis, highly vascularized capsules with central poorly contrast enhancing areas. In all cases there was laryngeal wall infiltration, in two dogs invasion of the laryngeal lumen and in one case invasion of the ventral muscular and subcutaneous plane. Metastases were found in retropharyngeal lymph nodes (three cases) and in the lung (two cases). Ectopic thyroid carcinoma should be considered in the differential diagnosis when a mass in the basihyoid region is present. Described CT features may be typical for ectopic thyroid neoplasia and could be used to help decide the therapeutic plan.

Evidence for calcitonin-producing cells in human lingual thyroids

CONTEXT

The thyroid contains two types of cells, the thyroid follicular cells and the calcitonin-producing cells. The site of origin of the thyroid follicular cells is the median thyroid anlage, an endothelial diverticulum in the midline of the ventral pharynx between the first and the second pharyngeal pouches. The ultimobranchial bodies (UBB), a pair of transient embryonic structures evaginated from the fourth pharyngeal pouch and located symmetrically on the sides of the developing neck, are the source of calcitonin-producing cells. In human embryos, the thyroid bud starts its migration at embryonic day 24 and reaches its final location in front of the trachea at embryonic day 45-50. The UBB fuse with the primitive thyroid when thyroid migration is completed. Lingual thyroids result from the failure of the thyroid precursor cells to migrate from the primordial pharynx to the anterior part of the neck. Therefore, calcitonin-producing cells are not expected to be present in lingual thyroids.

OBJECTIVE

Our objective was to determine whether calcitonin-producing C cells are present in ectopic lingual thyroids.

DESIGN, SETTING, PATIENTS, AND MAIN OUTCOME MEASURE

We performed calcitonin immunolabeling and transcript detection on four flash-frozen ectopic lingual thyroids. Additional calcitonin immunolabeling was performed on two other paraffin-embedded ectopic lingual thyroids.

RESULTS

We report evidence of calcitonin-producing cells in six independent cases of ectopic lingual thyroids.

CONCLUSION

The UBB are not the only source of calcitonin-producing cells in humans. Interactions between calcitonin-producing and thyroid follicular cells occur earlier than previously accepted.

Lingual and renal lymphoma in a cat

A domestic shorthair cat presented with a progressive history of polydipsia, lingual swelling and ulceration. The tongue was firm and grossly enlarged with associated regional lymphadenopathy. Surgical biopsies revealed lymphoma of the tongue. Following the procedure, the cat developed respiratory distress and was subsequently euthanased. Necropsy confirmed the diagnosis of lingual lymphoma and also identified lymphoma within the left kidney. This is the first report of lymphoma within the feline tongue in the literature.

Intrapericardial Ectopic Thyroid Carcinoma in a Cat

A 7-year-old spayed female domestic shorthair feline presented with tachycardia and was later euthanized due to a declining condition. On gross examination, the thoracic cavity contained an expansile, multiloculated mass that displaced the lungs dorsocaudally. The mass, within the pericardial sac, compressed adjacent myocardium. Cut surface revealed variably sized, fluid-filled spaces with multiple foci of hemorrhage and necrosis. Histologically, the mass was composed of solid foci of polygonal cells admixed with colloid-containing follicles. Immunohistochemical staining for thyroglobulin was positive, and staining for calcitonin was negative. Grossly, thyroid glands were normal, and serum thyroxine was within reference intervals.

Epithelial and pancreatic choristoma in bovine lymph nodes

Lymph nodes from 186 cows were evaluated as part of a bovine tuberculosis eradication programme. The mediastinal lymph nodes of 13 animals contained atypical structures. In 12 cases (6.45%) these consisted of multiple epithelial structures and, in one case, of pancreatic-like tissue. Immunohistochemistry (IHC) revealed that the epithelial structures were consistent with respiratory epithelium and with ectopic pancreatic tissue, respectively. To the best of our knowledge these are the first histological and immunohistochemical descriptions of epithelial and pancreatic choristomas in bovine lymph nodes.