The use of nuclear imaging for a mixed C cell microfollicular carcinoma of the thyroid gland in a mature horse

Abstract

SummaryA 15-year-old Boerperd stallion presented for thyroid enlargement associated with inappetance. Ultrasonographic examination of the thyroid gland revealed an enlarged left lobe, which, on cytological examination, contained numerous anaplastic cells. A mixed C cell microfollicular thyroid carcinoma was diagnosed following histopathological examination of the excisional biopsy specimen. In order to determine metastasis, pulmonary radiographs revealed a poorly-marginated soft tissue opacity caudo-dorsal to the cardiac silhouette. Thyroid and pulmonary scintigraphy was performed comparing 99m Tc-sestamibi with 99mTc-pertechnetate and no metastasis was detectable. Following hemithyroidectomy, the stallion made a full recovery without the need for neoadjuvant chemotherapy. Six months later, repeated thyroid and pulmonary scintigraphy using 99m Tc-sestamibi was normal.

Standing thyroidectomy in 10 horses

“…Thyroid enlargement can be related to goiter or neoplasia . Goiter refers to a non‐neoplastic enlargement of the thyroid due to an excess or deficiency of iodine in the diet, or due to hyperthyroidism . Neoplasia is the most common cause of progressive growth of the thyroid gland, with adenomas, adenocarcinomas, and C‐cell tumors most commonly reported in horses .…”

“…Neoplasia is the most common cause of progressive growth of the thyroid gland, with adenomas, adenocarcinomas, and C‐cell tumors most commonly reported in horses . Less commonly mixed follicular C‐cell carcinomas have been described . Thyroid tumors may occur in horses of all ages, but are most common in horses over 10 years of age, with pathological studies reporting an incidence of 30% for horses ≥10 years old and 75% in horses ≥20 years old .…”

“…For this reason if a benign enlargement is detected as an incidental finding during clinical examination, a conservative approach can usually be recommended . Thyroidectomy (hemi‐ or bilateral) is performed with the affected horse under general anesthesia (GA) . However, risks and complications associated with GA can be a limiting factor for the overall outcome, with a mortality risk of 1% reported for healthy horses undergoing GA .…”

The diagnosis, characterisation and treatment of a mixed C cell microfollicular thyroid carcinoma in a horse

“…The accompanying case report by Saulez et al . (2012) provides a description of a previously unreported form of thyroid carcinoma, a mixed C cell microfollicular carcinoma, in a 15‐year‐old horse, outlining the extensive diagnostic workup including endoscopy, ultrasonography, radiography, computed tomography (CT) and nuclear scintigraphy.…”

“…The accompanying case report by Saulez et al (2013) provides a description of a previously unreported form of thyroid carcinoma, a mixed C cell microfollicular carcinoma, in a 15-year-old horse, outlining the extensive diagnostic workup including endoscopy, ultrasonography, radiography, computed tomography (CT) and nuclear scintigraphy. This report describes the combination of these advanced imaging techniques, histomorphological with immunohistochemical characterisation and electron microscopy of this unusual thyroid neoplasia.…”