Thyroid nodule resident survival guide
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mahshid Mir, M.D. [2]
| Thyroid nodule Resident Survival Guide Microchapters |
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| Overview |
| Classification |
| Causes |
| FIRE |
| Diagnosis |
| Treatment |
| Do's |
| Don'ts |
Overview
Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. The American Thyroid Association has published guidelines for the management of thyroid nodules, which were updated in 2015. The major causes of thyroid nodule development include, multinodular (sporadic) goiter, Hashimoto's thyroiditis, cysts, macrofollicular/microfollicular adenomas, childhood radioiodine exposure, familial history, and gene mutations. Neck masses can be mistaken for thyroid nodules. The most important neck masses that can be mistaken with thyroid nodules include, thyroglossal duct cyst, parathyroid cancer, parathyroid cyst, and branchial cleft cyst. While the diagnosis of a thyroid nodule is established, thyroid nodule should be differentiated based on benign or malignant features and the type of nodule. Common risk factors associated with thyroid nodules include, older age, iodine deficiency, previous history of iodine deficiency and hypothyroidism, living in iodine deficient areas, family history of autoimmune diseases, multiparity, and smoking. A solitary thyroid nodule may become symptomatic if it grows rapidly due to hemorrhage or malignancies, invades laryngeal nerves, compressing nearby structures, and secretory nodules that produce TSH. Thyroid nodules may be a manifestation of thyroid cancer, that usually develops in the 6th decade of life, and start with symptoms such as weight loss, fatigue, and hoarseness. Without treatment, the patient with benign nodules may remain asymptomatic, while the patients with thyroid neoplasm may develop distant metastasis, which may eventually lead to death. The most common complications of thyroid nodules are hoarseness, horner's syndrome, nodule rupture, needle track seeding, hemorrhage/hematoma, dysphagia, upper airway obstruction, pain, skin burn, vasovagal reaction, hypothyroidism, transient thyrotoxicosis, anaphylactic reaction, thromboembolism, and pneumothorax. Physical examination should focus on the thyroid gland and the lateral and central neck and should assess for supraclavicular and submandibular adenopathy. In case of active hot thyroid nodules that produce thyroid hormones, antithyroid drugs should be administered, that include beta-blockers, antithyroid drugs (methimazole,carbimazole,propylthiouracil), radioactive iodine, and thyroidectomy. If the nodule excision treatment (lobectomy, isthmectomy, and total thyroidectomy) is not curative, then treatment with postoperative radioactive iodine (RAI) remnant ablation and recombinant human TSH–mediated therapy is recommended. Surgical management of thyroid nodule is performed in case of non-diagnostic or suspicious biopsy, for removal of primary thyroid cancer or for thyroid cancer staging for radioactive ablation and serum thyroglobulin monitoring. Primary prevention of thyroid nodule is aimed at prevention of thyroid cancer. Avoidance of exposure to radiation and monitoring the population with an increased risk of development of a malignant thyroid nodule play major roles in primary prevention. Secondary prevention of thyroid nodules focuses on prevention of recurrence of nodules. Different prevention strategies may be used depending upon whether the nodule is benign or malignant. In case of a malignant nodule, the major focus is on the prevention of recurrence after removal of a primary nodule. Post-operative periodic monitoring with serum thyroglobulin levels, radioactive iodine scanning, neck ultrasound and thyroid stimulating hormone (TSH) may decrease the chances of recurrence.
Classification
The various classification systems for thyroid nodules can be summarized as follows:
| Thyroid nodule classification | |||||||||||||||||||||||||||||||||||||
| Bethesda classification system | TIRAD classification system | ||||||||||||||||||||||||||||||||||||
| Based on thyroid cytopathology | Based on sonographic features | ||||||||||||||||||||||||||||||||||||
| •Benign •Nondiagnostic or Unsatisfactory •Follicular lesion of undetermined significance •Atypia of undetermined significance •Follicular neoplasm •Suspicious for a follicular neoplasm •Malignant | •TIRADS 1=Normal thyroid gland •TIRADS 2=Benign lesions •TIRADS 3=Probably benign lesions •TIRADS 4= Contain 1-4 suspicious features •TIRADS 5=Contain all five suspicious features •TIRADS 6=Biopsy proven malignancy | ||||||||||||||||||||||||||||||||||||
| Differentiated and anaplastic thyroid carcinoma | |||||||||||||||||||||||||||||||||||||
| TNM staging AJCC UICC 2017 | Classification based on their origin | ||||||||||||||||||||||||||||||||||||
| •Primary tumor (T) •Regional lymph nodes (N) •Distant metastasis (M) | Nonmedullary (epithelial) thyroid cancers (NMTCs) •Papillary cell tumors •Follicular tumors •Hurthle cell tumors •Anaplastic tumors | Medullary thyroid cancers | |||||||||||||||||||||||||||||||||||
Causes
Life-threatening causes
The most important genes which can lead to thyroid cancer include:[1][2][3]
Causes of malignant nodule mutations:
- Childhood radioiodine exposure
- Familial history
Common causes
The most important causes of thyroid nodule development include:[4][5][6]
- Causes of benign thyroid nodule:
- Multinodular (sporadic) goiter ("colloid adenoma")
- Hashimoto's (chronic lymphocytic) thyroiditis
- Cysts (colloid, simple, or hemorrhagic)
- Follicular adenomas
- Macrofollicular adenomas
- Microfollicular or cellular adenomas
- Hürthle cell (oxyphil cell) adenomas
- Macro- or microfollicular patterns
A Complete Diagnostic Approach and Management
Abbreviations:
TSH: Thyroid stimulating hormone, FNA: Fine needle aspiration, FLUS: Follicular lesion of undetermined significance, AUS: Atypia of undetermined significance.
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Do's
Thyroglobulin level monitoring
- Order serum thyroglobulin periodically during follow-up of patients with differentiated thyroid cancer who have undergone less than total thyroidectomy
- Order serum thyroglobulin periodically during follow-up of patients with differentiated thyroid cancer who have had a total thyroidectomy but not radioactive iodine ablation
Cervical ultrasound
- Perform neck ultrasound to evaluate thyroid 6–12 months following surgery
18FDG-PET scanning
- Consider 18FDG-PET scanning in high-risk differentiated thyroid cancer patients with elevated serum thyroglobulin (generally >10 ng/mL) and negative radioactive iodine imaging
CT scans
- Order chest CT scan with or without intravenous contrast in high-risk differentiated thyroid cancer patients with elevated serum thyroglobulin (generally >10 ng/mL) or rising thyroglobulin antibodies with or without negative radioactive iodine imaging
TSH range
- Maintain serum TSH below 0.1 mU/L in patients with a structural incomplete response to therapy, indefinitely in the absence of specific contraindications
- Maintain serum TSH between 0.5-2 mU/L in patients with an excellent or indeterminate response to therapy, especially those at low risk for recurrence
Surgery for nodal disease
- Perform surgery in patients with clinically apparent, macroscopic nodal disease
- Perform therapeutic compartmental central and/or lateral neck dissection in a previously operated compartment, in patients with biopsy-proven persistent or recurrent disease for central neck nodes ≥8 mm and lateral neck nodes ≥10 mm
- Perform compartmental surgery
- Perform combination of surgery and radioactive iodine and/or external beam radiation therapy (EBRT) in patients with aerodigestive invasive disease
- Order complete blood count and assessment of renal function before administration of radioactive iodine
- Discuss preventive strategies for dental caries with patients with xerostomia
Radioactive iodine therapy
- Order pregnancy test before radioactive iodine administration
- Administer radioactive iodine therapy in patients with iodine-avid bone metastases
- Administer radioactive iodine therapy in patients with pulmonary micrometastases and every 6-12 months
Don'ts
- Do not administer radioactive iodine to pregnant women
- Do not administer radioactive iodine to nursing women
- Do not perform surgery with focal “berry-picking” techniques
References
- ↑ Bomeli SR, LeBeau SO, Ferris RL (2010). "Evaluation of a thyroid nodule". Otolaryngol. Clin. North Am. 43 (2): 229–38, vii. doi:10.1016/j.otc.2010.01.002. PMC 2879398. PMID 20510711.
- ↑ Jena A, Patnayak R, Prakash J, Sachan A, Suresh V, Lakshmi AY (2015). "Malignancy in solitary thyroid nodule: A clinicoradiopathological evaluation". Indian J Endocrinol Metab. 19 (4): 498–503. doi:10.4103/2230-8210.159056. PMC 4481656. PMID 26180765.
- ↑ Chibishev A, Simonovska N, Shikole A (2010). "Post-corrosive injuries of upper gastrointestinal tract". Prilozi. 31 (1): 297–316. PMID 20693948.
- ↑ Bomeli SR, LeBeau SO, Ferris RL (2010). "Evaluation of a thyroid nodule". Otolaryngol. Clin. North Am. 43 (2): 229–38, vii. doi:10.1016/j.otc.2010.01.002. PMC 2879398. PMID 20510711.
- ↑ Jena A, Patnayak R, Prakash J, Sachan A, Suresh V, Lakshmi AY (2015). "Malignancy in solitary thyroid nodule: A clinicoradiopathological evaluation". Indian J Endocrinol Metab. 19 (4): 498–503. doi:10.4103/2230-8210.159056. PMC 4481656. PMID 26180765.
- ↑ Chibishev A, Simonovska N, Shikole A (2010). "Post-corrosive injuries of upper gastrointestinal tract". Prilozi. 31 (1): 297–316. PMID 20693948.