COMPARISON BETWEEN CLINICAL, ULTRASOUND, CT, MRI, AND PATHOLOGY FINDINGS IN DOGS PRESENTED FOR SUSPECTED THYROID CARCINOMA

Sodium iodide symporter immunolabelling as a predictor of clinical iodide uptake in canine thyroid carcinoma: A preliminary study

Thyroid follicular tumours may take up iodide via the sodium-iodide symporter. Knowledge of iodide uptake could then allow treatment with I-131 in dogs with high-risk tumours. The objective of this study was to determine the relationship between clinically detectable iodide uptake (as determined by scintigraphy and/or thyroxine concentrations) and sodium iodide symporter immunohistochemical labelling on histologically fixed thyroid tumours. Nineteen dogs were identified who were diagnosed with thyroid carcinoma and underwent surgery from November 2017 to July 2021. All had recorded thyroid hormone concentrations and were hyperthyroid and/or underwent preoperative nuclear imaging using planar scintigraphy (technetium-99m or I-123), or I-124 PET-CT. All dogs subsequently underwent surgery to remove the thyroid mass. Twenty-two tumours were submitted for histopathologic analysis immediately following surgery, which confirmed a diagnosis of thyroid carcinoma for each tumour. Images and/or thyroid hormone concentrations were reviewed for the included cases, and tumours were sorted into an avid/functional group (group 1) and a non-avid/functional group (group 2). The tumour tissues were re-examined histologically using sodium iodide symporter (NIS) immunohistochemistry (IHC). Group 1 contained 15 avid/functional tumours. Twelve of these tumours had membranous NIS IHC labelling. Group 2 contained 7 non-avid tumours. One of these tumours had membranous NIS IHC labelling. This resulted in an overall sensitivity and specificity for identification of avid/functional tumours with membranous NIS of 80.0% and 85.7%, respectively. NIS IHC may predict ion trapping in canine follicular thyroid tumours. Further studies using iodide-based imaging are warranted to better determine the clinical utility of this diagnostic modality.

Two-Dimensional Shear-Wave Elastography of the Thyroid in Clinically Healthy Dogs in Different Age Groups

The thyroid of dogs has not been extensively studied in 2D shear-wave elastography, making it challenging to apply this technique in the diagnosis of thyroid diseases in a non-invasive manner. The aim of this study is to evaluate the thyroid glands of healthy dogs using 2D shear-wave elastography in order to establish qualitative and quantitative parameters of tissue stiffness in dogs in different age groups. A total of 31 dogs of various breeds, sexes, and sizes were evaluated. Animals with clinical signs or ultrasound findings indicative of endocrine disease or thyroid lesions were excluded from the study. The shear-wave velocity data in meters per second (m/s) and color elastograms were evaluated and calculated using QelaXto™ 2D software. A healthy thyroid exhibits a blue-color elastogram, indicative of low stiffness. The reference range for the shear-wave velocity of thyroid tissue assessed by 2D shear-wave elastography can be between 1.6 and 2.0 m/s, with a variation of ±0.889 in adult and senior dogs.

Bilateral thyroid adenomas in an alpaca

A 7-year-old neutered male alpaca (Vicugna pacos) was presented for evaluation of a 3-year history of large, bilateral, firm ventral cervical masses causing esophageal and tracheal impingement. Ultrasound examination, radiographic evaluation, histopathological findings, and magnetic resonance imaging confirmed the masses to be bilateral thyroid adenomas. Conservative medical treatment by unilateral chemical ablation, using 10% formalin by aspiration technique, was performed on the left mass. Chemical ablation proved to be effective in decreasing the size of the mass, with no apparent adverse effects. To our knowledge, this case is the first known report of bilateral thyroid adenomas in an alpaca, a condition previously described in humans, horses, dogs, and cats.

Assessment of qualitative and quantitative parameters of healthy thyroid gland in adult horses by magnetic resonance imaging

In humans and pets, magnetic resonance imaging (MRI) provides important adjunctive anatomic information about the thyroid and its adjacent structures. To the best of our knowledge, however, no studies have been reported regarding the use of MRI for thyroid evaluation in horses. The aim of this study was to obtain qualitative and quantitative parameters of healthy thyroid gland in adult horses by MRI. Eleven horses were submitted to thyroid MRI evaluation. The healthy thyroid of these animals was ensured by normal examinations performed before (free thyroxine and ultrasound) and after (cytology) to MRI. It was concluded that the dorsal spin-echo T1-weighted, fast spin-echo T2-weighted, sagittal STIR and a three-dimensional T1-weighted gradient echo were the sequences that best characterized the thyroid lobes. Qualitatively, there was a significant variation in the elliptical format of some lobes considering the sagittal plane, which oscillated between rounded and flattened conformation. Excellent reproducibility of the quantitative thyroid parameters obtained was verified. The thyroid gland total volume mean of observers was 14.31 cm³ (±0.69). In relation with comparisons between quantitative parameters of left and right lobes, only differences regarding their respective lengths were observed. Thus, we can infer that the difference in some thyroid lobes format can be explained by the significant variation identified between left and right lobes lengths.

Outcome and postoperative complications in 73 dogs with thyroid carcinoma with gross vascular invasion managed with thyroidectomy

Excellent outcomes have been reported following thyroidectomy for thyroid carcinoma in dogs, but outcomes for thyroid carcinomas with gross vascular invasion are poorly described. This study describes the clinical outcomes and complications in dogs with thyroid carcinomas with gross vascular invasion undergoing thyroidectomy. Medical records of dogs that underwent thyroidectomy between January 1st 2010 and December 31st 2019 were reviewed at 10 hospitals. Signalment, diagnostic data, primary and adjuvant treatments performed, and outcome were abstracted. Survival was calculated using Kaplan-Meier analysis. Multiple logistic regression was used to identify variables associated with disease-specific survival. Seventy-three dogs were included, of which 58 underwent unilateral thyroidectomy and 15 underwent bilateral thyroidectomy. Complications were reported in five dogs (three major, two minor; 6.8%) intraoperatively and 12 dogs (two major leading to death, 10 minor; 16.4%) postoperatively. Seven (9.6%) dogs developed locoregional recurrence at a median of 238 days postoperatively (range: 15-730 days). Distant metastasis was suspected or confirmed in nine dogs (12.3%) at a median of 375 days postoperatively (range: 50-890 days). Twenty-seven dogs (37%) received adjuvant therapy (chemotherapy: n = 21; radiotherapy: n = 6). Thirty-nine dogs were euthanized or died, with 20 deaths related to disease (n = 10) or of unknown cause (n = 10), 19 due to unrelated causes, and nine lost to follow-up. Median overall and disease-specific survival were 621 days and not reached respectively. One-year disease-specific survival rate was 82.5%. No variables were associated with disease-specific survival in our dataset. Surgery may be considered for loco-regional therapy in dogs with thyroid carcinoma with gross vascular invasion.

Canine thyroid carcinoma prognosis following the utilisation of computed tomography assisted staging

BACKGROUND

Metastatic disease is frequently present at the time of diagnosis of canine thyroid carcinoma; however, utilisation of computed tomography (CT) alone for staging pre-treatment has been rarely reported in the veterinary literature.

METHODS

The aims of this retrospective study were to stage affected dogs using CT findings of the cervical and thoracic regions, combined with histopathology/cytology results, in order to assess whether metastatic disease/WHO staging was of prognostic significance.

RESULTS

Fifty-eight dogs were included in the study. Classification of cases into WHO stages I, II, III and IV were 10%, 50%, 9% and 31%, respectively. No statistically significant effect of WHO stage classification on overall survival/follow-up time was found (P = .576). Surgery resulted in a statistically significant increase in overall survival/follow-up time (P < .01). There was no statistically significant effect on overall survival/follow-up time in dogs that received medical therapy, either as sole therapy or as an adjunctive post-surgery (P = .198).

CONCLUSION

In summary, this study documents the metastatic rate of canine thyroid carcinoma using CT for staging pre-treatment. Staging utilising CT revealed a higher distant metastatic rate in dogs with thyroid carcinoma when compared to historical studies using different imaging techniques. As long-term outcomes are possible for cases with advanced disease, surgical intervention could still be considered.

Metastasis to ipsilateral medial retropharyngeal and deep cervical lymph nodes in 22 dogs with thyroid carcinoma

OBJECTIVE

To determine the rate of nodal metastasis to the medial retropharyngeal (MRP) and deep cervical lymph nodes in dogs surgically treated for thyroid carcinoma.

STUDY DESIGN

Retrospective study.

ANIMALS

Twenty-two client-owned dogs.

METHODS

Medical records between July 2015 and October 2019 at the Universities of Missouri and Florida were reviewed. Dogs that underwent thyroidectomy with concurrent elective MRP lymphadenectomy ± deep cervical lymphadenectomy were included. Tumor site, preoperative staging, and histopathological findings were recorded.

RESULTS

Twenty-two dogs with 26 total thyroid carcinomas were included. Primary tumors were lateralized in 19 dogs, bilateral in two dogs, and bilateral and midline ectopic in one dog. All dogs underwent ipsilateral MRP resection, including bilateral resection in dogs with bilateral tumors. Three contralateral MRP lymph nodes were excised from dogs with unilateral carcinomas. Four deep cervical lymph nodes and one superficial cervical lymph node were excised. Metastases were identified in 14 lymph nodes in 10 of 22 (45%) dogs. All four excised deep cervical lymph nodes and one contralateral MRP lymph node were identified as metastatic. Size of deposit could be classified in 13 of 14 metastatic lymph nodes. Macrometastasis was detected in seven lymph nodes, micrometastasis was detected in one node, and isolated tumor cells were detected in five lymph nodes.

CONCLUSION

Regional metastasis was common within the lymph nodes sampled in this population of dogs with thyroid carcinoma.

CLINICAL SIGNIFICANCE

These results provide evidence to justify further exploration of a larger population to verify the rate of regional metastasis and determine the prognostic impact of nodal metastasis.

Pre-contrast CT attenuation of the thyroid gland is lower in brachycephalic dogs versus non-brachycephalic dogs

Computed tomography has been used in human medicine to evaluate the thyroid gland functional status by means of Hounsfield units (HU). Studies describing attenuation value abnormalities, other than those in thyroid neoplasia, lack in veterinary medicine. The authors have observed a subjective reduction in thyroid attenuation in some patients undergoing CT for reasons other than thyroid disease. This finding has been identified more frequently in brachycephalic breeds compared to non-brachycephalic breeds. In order to determine the thyroid gland attenuation variability on CT, a retrospective and prospective, analytical, cross-sectional study was performed. The thyroid attenuation values of 65 client-owned dogs were assessed using a 16-slice helical CT scanner. Differences in attenuation between brachycephalic and non-brachycephalic dogs were estimated by Welch's t-test. Serum TT4 and TSH levels were available in 26 patients. Statistically significant differences were observed in the pre-contrast attenuation value ranges between brachycephalic and non-brachycephalic dogs (P = .04). The pre-contrast attenuation value range for the brachycephalic group was 69.1-108 HU while being 75.8-121 HU for the non-brachycephalic group. No significant correlation was found between thyroid attenuation and serum thyroid hormone levels in our population (P > .6). All patients with hypoattenuating thyroid were brachycephalic and reported euthyroid. In conclusion, brachycephalic dogs seem to have a pre-contrast attenuation thyroid gland range lower than non-brachycephalic dogs. The present study contributes to the veterinary literature by providing a new thyroid attenuation value range for brachycephalic breeds. Additionally, hypoattenuating thyroid glands may be found in dogs with normal TT4 and TSH values.

Safety and efficacy of stereotactic body radiation therapy (SBRT) for the treatment of canine thyroid carcinoma

Thyroid carcinoma develops spontaneously in dogs, with only 25% to 50% of cases amenable to surgery at diagnosis. Local control for unresectable tumours can be provided with external beam radiotherapy. The aim of this retrospective study is to describe the safety and efficacy of stereotactic body radiation therapy (SBRT) for treatment of canine thyroid carcinoma. Twenty-three dogs met inclusion criteria; median tumour volume before SBRT was 129.9 cm³ (range, 2.7-452.8 cm³ ). Sixteen patients (70%) had unresectable tumours. Pulmonary metastasis was present or suspected in 10 patients (44%) before SBRT. Patients were prescribed 15 to 40 Gy to targeted tumour volume in one to five fractions. Twenty patients evaluated had overall response rate of 70% (complete response, n = 4; partial response, n = 10). Thirteen out of sixteen (81%) symptomatic patients had clinical improvement within a median time of 16 days (range, 2-79 days). Median progression free survival (MPFS) was 315 days. Median survival time (MST) was 362 days. Nine patients (39%) had grade 1 acute radiation toxicity. Three patients had grade 1 late radiation toxicity (two leukotrichia and one [4%] with intermittent cough). Responders had significantly longer MPFS (362 vs 90 days; HR 4.3; 95% CI 1.4-13.5; P = .013) and MST (455 vs 90 days; HR 2.9; 95% CI 1-8.4; P = .053). Presenting with metastasis was not a significant negative prognostic factor (MST 347 vs 348 days without metastasis; P = .352). SBRT is a safe and effective treatment modality for non-resectable canine thyroid carcinoma.

CT angiography and MRI imaging features do not predict the tumor type and grade of feline injection site sarcoma

Computed tomographic angiography (CTA) and magnetic resonance imaging (MRI) have been described as methods for preoperative surgical planning in cats with feline injection site sarcomas (FISS), however, few published studies have compared these modalities. The objective of this retrospective, secondary analysis study was to determine if imaging features of FISS on CTA and MRI are predictive of neoplastic peritumoral projections. Archived data from a previous prospective study were retrieved for 10 cats with FISS. All cats had been evaluated in a single anesthetic episode with MRI and dual phase CT (CTA) imaging followed by surgical removal. Histopathological grading and targeted histopathology of imaging-identified peritumoral projections were performed. Two observers evaluated the CTA and MRI studies for FISS shape, margination, size, enhancement pattern, postcontrast uniformity, pre- and postcontrast margination, the number of muscles involved, mass mineralization, and bone lysis. Metal was present in the imaging field of three of 10 cats, resulting in one nondiagnostic MRI. Peritumoral projections were detected in all cats with both imaging modalities, and most were benign. At least one neoplastic peritumoral projection was detected in six cats using MRI, five cats using CTA, and three cats with both modalities. Higher grade FISS were larger than low grade using MRI, and FISS were larger using MRI. Other FISS imaging features using MRI and CTA were similar. Findings supported use of either MRI or CTA for detecting neoplastic peritumoral projections in cats with FISS. Authors recommend CTA for cats with known metallic objects in the scan field.

Imaging in Non-neurologic Oncologic Treatment Planning of the Head and Neck

Imaging is critical for the diagnosis and staging of veterinary oncology patients. Although cytology or biopsy is generally required for diagnosis, imaging characteristics inform the likelihood of a cancer diagnosis, can result in a prioritized list of differentials that guide further staging tests, and assist in the planning of surgery, radiation, and chemotherapy options. Advanced imaging, such as CT and MRI, can better define the extent of disease for surgical and radiation planning for head and neck cancer cases in particular. Additionally, new imaging technologies are continually being translated into veterinary fields, and they may provide more options for cancer patients as they become more widely available.

VMAT Stereotactic Body Radiation Therapy in a Multimodal Approach to a Carotid Paraganglioma in a Dog

A 7 yr old female pit bull terrier was presented for a cervical soft tissue swelling located in the left jugular region. No abnormalities were present at physical examination or in the laboratory workup. Computed tomography and MRI scans showed a well-defined, ovoid, single mass in the left dorsal cervical region connected to the common carotid artery, histologically consistent with carotid body paraganglioma. The mass was surgically resected. Frameless stereotactic body radiation therapy with volumetric modulated arc therapy was set up as adjuvant treatment. After radiation therapy, systemic chemotherapy with carboplatin was started. During the first yr of follow-up, acute grade I dermatitis and grade I left-side laryngeal mucositis were recognized. One yr after radiation therapy, no signs of late radiotoxicity or tumor recurrence were observed. Grade I thrombocytopenia concurrent with chemotherapy was observed. This is the first reported case of a carotid body paraganglioma treated by multimodal therapy, with surgical resection and adjuvant radiotherapy and chemotherapy. Stereotactic body radiation therapy with volumetric modulated arc therapy treatment after surgery provided excellent disease control and was well tolerated with slight side effects.

Dietary Management of Hyperthyroidism in a Dog

An 8 yr old female spayed golden retriever presented for a routine exam during which ventral cervical soft tissue masses were identified. History included weight loss, increased activity and appetite, gagging, and occasional diarrhea. Exam findings included a body condition score of 4/9 and palpable ventral cervical nodules. A serum thyroxine (T4) value was 8.0 ug/dL (normal = 0.8-3.5ug/dL). Doppler systolic blood pressure readings ranged from 200-210 mmHg (normal systolic blood pressure <150 mmHg). The diagnosis was hyperthyroidism due to active thyroid masses. Due to financial constraints, the owner elected conservative management. Initial treatment with methimazole resulted in a decreased T4 value of 5.0 ug/dL at approximately 4 mo after initiation of treatment. A commercially available iodine-restricted feline diet was fed and this resulted in further reduction in serum T4 levels, improved sleeping cycles, reduced anxiety, and reduced systolic blood pressure. A temporary suspension of iodine-restricted feline diet for 2 mo resulted in increases in serum T4 concentrations, which, subsequently, decreased with re-introduction of the diet. Roughly 10 mo after initiation of the therapeutic diet and 16 mo after intial diagnosis, the dog remains relatively normal clinically despite active growing cervical masses with T4 concentration of 2.3 ug/dL.

Comparison of Clinical and Pathological Diagnoses in Cats and Dogs

The comparison of clinical ante-mortem and pathological post-mortem diagnoses is a prerequisite for quality control, but is rarely done in veterinary medicine. This study reports the occurrence and concurrence of clinical and pathological diagnoses linked to death in 1,000 cats and 1,000 dogs examined and subjected to necropsy examination at the University of Zurich, Switzerland. Potential factors influencing the correlation between diagnoses were examined retrospectively. In 5.8% of cats and 5.2% of dogs no diagnosis was made; in 2.6% and 3.8% of cases only a clinical, and in 17.8% and 11.2%, respectively, only a pathological diagnosis was available. Of the 73.8% of cats and 79.8% of dogs with both diagnoses present, 38.3% and 36.2% were in agreement, while there was disagreement in 17.9% and 16.0%, respectively. The remaining cases (43.8% and 47.8%) had different levels of further diagnostic procedures following necropsy examination. In both species, the manner of death, the clinical discipline submitting the animal for necropsy examination and the quality of the necropsy submission request, as well as the timespan between death and necropsy examination in dogs, proved to influence the concurrence between diagnoses. In contrast, the organ system affected and the type of disease entity were, for both species, the most influential factors in the concurrence of diagnoses. Therefore, in veterinary medicine, even in times of improving diagnostic abilities, necropsy examination still reveals important information for quality control and education.

Monitoring the Growth of an Orthotopic Tumour Xenograft Model: Multi-Modal Imaging Assessment with Benchtop MRI (1T), High-Field MRI (9.4T), Ultrasound and Bioluminescence

BACKGROUND

Research using orthotopic and transgenic models of cancer requires imaging methods to non-invasively quantify tumour burden. As the choice of appropriate imaging modality is wide-ranging, this study aimed to compare low-field (1T) magnetic resonance imaging (MRI), a novel and relatively low-cost system, against established preclinical techniques: bioluminescence imaging (BLI), ultrasound imaging (US), and high-field (9.4T) MRI.

METHODS

A model of colorectal metastasis to the liver was established in eight mice, which were imaged with each modality over four weeks post-implantation. Tumour burden was assessed from manually segmented regions.

RESULTS

All four imaging systems provided sufficient contrast to detect tumours in all of the mice after two weeks. No significant difference was detected between tumour doubling times estimated by low-field MRI, ultrasound imaging or high-field MRI. A strong correlation was measured between high-field MRI estimates of tumour burden and all the other modalities (p < 0.001, Pearson).

CONCLUSION

These results suggest that both low-field MRI and ultrasound imaging are accurate modalities for characterising the growth of preclinical tumour models.

Nanosized Ultrasound Enhanced-Contrast Agent for in Vivo Tumor Imaging via Intravenous Injection

To enhance the detection limit of ultrasound (US) imaging, ultrasound enhanced-contrast agents (UECAs) that can go preferentially to the target tissue such as a tumor and amplify the US signal have been developed. However, nanosized UECAs among various UECAs developed are very limited to clearly demonstrate proper ability for selective tumor detection by US imaging upon their intravenous injection. In this study, we prepared CaCO3 nanoparticles that were formed inside a flexible and biocompatible pluronic-based nanocarrier. This nanosized UECA was stable in serum-containing media and generated CO2, more preferentially at low pH; thus, it could be detected by US imaging. After intravenous injection into tumor-bearing mice, this nanosized UECA showed a significant US contrast enhancement at the tumor site in 1 h, in contrast to no change in the liver, followed by a rapid clearance from the body in 24 h. Therefore, the present nanosized UECA could be applied as an effective diagnostic modality for in vivo tumor imaging by ultrasonography.

CLINICAL AND MAGNETIC RESONANCE IMAGING FEATURES OF INFLAMMATORY VERSUS NEOPLASTIC MEDIAL RETROPHARYNGEAL LYMPH NODE MASS LESIONS IN DOGS AND CATS

Medial retropharyngeal lymph node (MRLN) mass lesions are a common cause of cranial cervical masses in dogs and cats, and are predominantly due to metastatic neoplasia, primary neoplasia, or inflammatory lymphadenitis. The purpose of this retrospective cross-sectional study was to test the hypothesis that clinical and magnetic resonance imaging (MRI) characteristics for dogs and cats with MRLN mass lesions would differ for inflammatory vs. neoplastic etiologies. Dogs and cats with MRLN mass lesions that had undergone MRI and had a confirmed cytological or histopathological diagnosis were recruited from medical record archives. Clinical findings were recorded by one observer and MRI characteristics were recorded by two other observers who were unaware of clinical findings. A total of 31 patients were sampled, with 15 in the inflammatory lymphadenitis group and 16 in the neoplasia group. Patients with inflammatory lymphadenitis were more likely to be younger and present with lethargy (P = 0.001), pyrexia (P = 0.000), and neck pain (P = 0.006). Patients with inflammatory lymphadenitis were also more likely to have a leukocystosis (P = 0.02) and segmental neutrophilia (P = 0.001). Inflammatory masses were more likely to have moderate or marked MRI perinodal contrast enhancement (P = 0.021) and local muscle contrast enhancement (P = 0.03) whereas the neoplastic masses were more likely to have greater MRI width (P = 0.002) and height (P = 0.009). In conclusion, findings indicated that some clinical and MRI characteristics differed for dogs and cats with inflammatory vs. neoplastic medial retropharyngeal lymph node masses. Although histopathological or cytological diagnosis remains necessary for confirmation, these findings may help with the ranking of differential diagnoses of future cases.

Clinical, pathologic, and immunohistochemical prognostic factors in dogs with thyroid carcinoma

Background

Prognostic markers for dogs with thyroid tumors are limited.

Hypothesis/Objectives

To identify clinical, pathologic, and immunohistochemical prognostic factors for dogs with thyroid tumors.

Animals

Seventy dogs with thyroid neoplasia.

Methods

Retrospective study. Dogs with thyroid neoplasia were included when follow‐up information and formalin‐fixed paraffin‐embedded tumor samples were available. Immunohistochemistry (IHC) was performed for thyroglobulin, calcitonin, Ki‐67, and E‐cadherin. Correlation of tumor variables (diameter, volume, localization, scintigraphic uptake, thyroid function, IHC) with local invasiveness and metastatic disease was performed on all tumor samples. Forty‐four dogs treated by thyroidectomy were included in a survival analysis.

Results

Fifty dogs (71%) had differentiated follicular cell thyroid carcinoma (dFTC) and 20 (29%) had medullary thyroid carcinoma (MTC). At diagnosis, tumor diameter (P = .007; P = .038), tumor volume (P = .020), tumor fixation (P = .002), ectopic location (P = .002), follicular cell origin (P = .044), and Ki‐67 (P = .038) were positively associated with local invasiveness; tumor diameter (P = .002), tumor volume (P = .023), and bilateral location (P = .012) were positively associated with presence of distant metastases. Forty‐four dogs (28 dFTC, 16 MTC; stage I–III) underwent thyroidectomy. Outcome was comparable between dogs with dFTC and MTC. Macroscopic (P = .007) and histologic (P = .046) vascular invasion were independent negative predictors for disease‐free survival. Although time to presentation, histologic vascular invasion and Ki‐67 were negatively associated with time to metastases, and time to presentation was negatively associated with time to recurrence, no independent predictors were found. E‐cadherin expression was not associated with outcome.

Conclusions and Clinical Importance

Prognostic factors have been identified that provide relevant information for owners and clinicians.

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.

Prevalence of incidental thyroid nodules in ultrasound studies of dogs with hypercalcemia (2008-2013)

Ultrasound is commonly used to evaluate the cervical region in dogs with hypercalcemia due to suspected hyperparathyroidism. Incidental thyroid nodules may be detected during these studies, however little information has been published to guide clinical decision-making when this occurs. The purpose of this cross-sectional study was to determine the prevalence of incidental thyroid nodules in hypercalcemic dogs undergoing cervical ultrasound at our hospital during the period of 2008-2013. Dogs with a palpable neck mass were excluded. Cervical ultrasound images for each dog were retrieved and reviewed by a board certified veterinary radiologist who was unaware of patient outcome. Presence, number, and dimensions of thyroid nodules were recorded. Results of thyroid nodule aspirate, biopsy or necropsy were recorded from medical records when available. Ninety-one dogs met inclusion criteria. Of these, 14/91 (15%) dogs had at least one thyroid nodule. Mean (± standard deviation) thyroid gland nodule length, width, and height were 1.51 ± 0.74, 0.96 ± 0.73, and 0.75 ± 0.36 cm, respectively. A histologic diagnosis was available for the incidental thyroid lesions in eight dogs, including one dog with two nodules. Confirmed diagnoses for these nodules were thyroid cyst (3/9, 33%), thyroid adenoma (3/9, 33%), thyroid adenocarcinoma (2/9, 22%) and nodular hyperplasia (1/9, 11%). Findings indicated that incidental thyroid nodules may be present in hypercalcemic dogs with no palpable neck mass and no clinical signs of thyroid disease. Some of these nodules may be malignant and therefore a recommendation for cytology or biopsy may be justified.

All lesions great and small, part 2. Diagnostic cytology in veterinary medicine

This is the second in a two‐part review of diagnostic cytopathology in veterinary medicine. As in human medicine, cytopathology is a minimally invasive, rapid, and cost‐effective diagnostic modality with broad utilization. In this second part, the diagnostic applications of cytology in respiratory, gastrointestinal, genitourinary, endocrine, ocular, and central nervous system tissues are discussed with a section describing fluid analysis in veterinary medicine. As noted in the previous manuscript, which characterized the cytology of the skin/subcutis, musculoskeletal, and lymphoid tissues, the interpretation of veterinary cytology samples must be undertaken with extensive knowledge of the breadth of animal species, including familiarity with the frequency and clinical progression of diseases, both of which can be influenced by species, breed, and husbandry conditions. Similar to part one, this review focuses on the most common domestic companion animal species (dog, cat, and horse) and highlights lesions that are either unique to veterinary species or have relevant correlates in people. The cytologic features and biological behavior of similar lesions are compared, and selected mechanisms of disease and ancillary diagnostics are reviewed when appropriate. Supporting figures illustrate a subset of lesions. While not an exhaustive archive of veterinary cytology, the goal is to give cytopathologists working in human medicine a general impression of correlates and unique entities in veterinary practice. Diagn. Cytopathol. 2014;42:544–552. © 2014 Wiley Periodicals, Inc.

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.

Hyperthyroidism and hyperparathyroidism in guinea pigs (Cavia porcellus)

Abnormal conditions of the thyroid and parathyroid in the guinea pig appear in the English-language scientific literature on an emerging basis. Although true descriptions of abnormal thyroid and parathyroid anatomy or morphology are not new findings, the clinical condition of abnormal thyroid or parathyroid function seems to be a more common observation by clinicians in recent years. This article is an overview of general clinical conditions and adequate diagnosis, and offers treatment options.