THYROID NODULE - AMERICAN THYROID ASOCIATION GUIDE (REVIEW)

Thyroid nodules

Epidemiologic

studies have shown the prevalence of palpablethyroid nodules to be approximately 5% in women and 1% in men living in iodine-sufficient parts of the world (1,2). In contrast, high-resolution ultrasound can detect thyroid nodules in 19%–67% of randomly selected individuals with higher frequencies in women and the elderly (3). The clinical importance of thyroid nodules rests with the need to exclude thyroid cancer that occurs in 5%–10% depending on age, gender, radiation exposure history, family history, and other factors (4, 5). Differentiated thyroid cancer, which includes papillary and follicular cancer, comprises the vast majority (90%) of all thyroid cancers

Generally, only nodules larger than 1 cm should be evaluated, because they have the potential to be clinically significant cancers. Occasionally, there may be nodules smaller than 1 cm that require evaluation, because of suspicious ultrasound findings, a history of head and neck irradiation, or

a positive family history of thyroid cancer. Pertinent historical factors predicting malignancy include

a history of head and neck irradiation, total body irradiation

for bone marrow transplantation (16), family history of thyroid

carcinoma in a first-degree relative, exposure to fallout

from Chernobyl under the age of 14 years (17), and rapid

growth and hoarseness. Pertinent physical findings suggesting

possible malignancy include vocal cord paralysis, ipsilateral

cervical lymphadenopathy and fixation of the nodule

to surrounding tissues.

R1. Every patient with a mass of 1-1.5cm should be measured of tsh

With the discovery

of a thyroid nodule larger than 1–1.5 cm in any diameter,

a serum thyrotropin (TSH) level should be obtained. If

the serum TSH is subnormal, a radionuclide thyroid scan

should be obtained to document whether the nodule is functioning

(i.e., has tracer uptake greater than the surrounding

normal thyroid), isofunctioning or “warm” (i.e., has tracer

uptake equal to the surrounding thyroid), or nonfunctioning

(i.e., has uptake less than the surrounding thyroid tissue). The US should answer Is there truly a nodule that

corresponds to the palpable abnormality? Is the nodule

greater than 50% cystic? Is the nodule located posteriorly in

the thyroid gland? Even if the TSH is elevated, FNA is recommended

because the rate of malignancy in nodules is similar

in thyroid glands involved with Hashimoto’s thyroiditis

as in normal thyroid glands.

R2. Every patient with one or more nodules should performed a US.

R3. Routine measurement of TG is not needed.

R4. Serum calcitonin > 100, a medullar carcinoma is likely. Not a real recommendation

R6. Cystic nodules that repeatedly yield nondiagnostic aspirates

need close observation or surgical excision. Surgery

should be more strongly considered if the cytologically nondiagnostic

nodule is solid—Recommendation A

R8. At the present time, the use of specific molecular markers

to improve the diagnostic accuracy of indeterminate nodules

is not recommended—Recommendation

R9. If the cytology reading is indeterminate (often termed

“suspicious,” “follicular lesion,” or “follicular neoplasm”), a

radioiodine thyroid scan should be considered, if not already

done. If a concordant autonomously functioning nodule is

not seen, lobectomy or total thyroidectomy should be considered—

Recommendation B

R10. If the reading is “suspicious for papillary carcinoma or

Hürthle cell neoplasm,” a radionuclide scan is not needed,

and either lobectomy or total thyroidectomy is recommended—

Recommendation A

Sonographic

characteristics are superior to nodule size for identifying

nodules that are more likely to be malignant (37,38) and include

the presence of microcalcifications, hypoechogenicity

(darker than the surrounding thyroid parenchyma) of a solid

nodule, and intranodular hypervascularity

In the presence of two or more thyroid nodules larger

than 1–1.5 cm, those with a suspicious sonographic appearance

should be aspirated preferentially

R13. A low or low-normal serum TSH concentration may

suggest the presence of autonomous nodule(s). A radioiodine

scan should be performed and directly compared to the

ultrasound images to determine functionality of each nodule

larger than 1–1.5 cm. FNA should then be considered

only for those isofunctioning or nonfunctioning nodules,

among which those with suspicious sonographic features

should be aspirated preferentially—Recommendation B

R14. Easily palpable benign nodules do not require sonographic

monitoring, but patients should be followed clinically

at 6–18 month intervals. It is recommended that all other benign

thyroid nodules be followed with serial ultrasound examinations

6–18 months after initial FNA. If nodule size is

stable, the interval before the next follow-up clinical examination

or ultrasound may be longer—Recommendation B

R15. If there is evidence for nodule growth either by palpation

or sonographically, repeat FNA, preferably with ultrasound

guidance—Recommendation B

R17. Patients with growing nodules that are benign after repeat

biopsy should be considered for continued monitoring

or intervention with surgery based on symptoms and clinical

concern—Recommendation C.

R19. For euthyroid and hypothyroid pregnant women with

thyroid nodules, FNA should be performed. For women with

suppressed serum TSH levels that persist after the first

trimester, FNA may be deferred until after pregnancy when

a radionuclide scan can be performed to evaluate nodule

function—Recommendation A

R20. A nodule with malignant cytology discovered early in

pregnancy should be monitored sonographically and if it

grows substantially (as defined above) by 24 weeks’ gestation,

surgery should be performed at that point. However,

if it remains stable by midgestation or if it is diagnosed in

the second half of pregnancy, surgery may be performed after

delivery—Recommendation C

References

- Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer - American Thyroid Asociation. PDF Download