Thyroid Nodule
meduploader - 06-30-09 12:48

Nodules are more common in women but are more likely to be malignant in men. Radiation exposure (e.g., Chernobyl; treatment of childhood acne) is a major risk factor. The “90%” mnemonic applies:
90% of nodules are benign.
90% of nodules are cold on RAI uptake scan; 15–20% of these are malignant and 1% of hot nodules are malignant.
90% of thyroid malignancies present as a thyroid nodule or lump.
> 90% of cancers are either papillary or follicular, which carry the best prognoses.
Present with a firm, palpable nodule.
Cervical lymphadenopathy and hoarseness are concerning signs.
Often found incidentally on radiologic studies done for other purposes.
Thyroid nodules may be benign or represent one of four main types of cancer: 1° thyroid cancer:
Papillary: Most common; spreads lymphatically. Has an excellent prognosis overall, with a > 95% five-year survival for all but metastatic disease.
Follicular: More aggressive; spreads locally and hematogenously. Can metastasize to the bone, lungs, and brain. Rarely produces thyroid hormone.
Medullary: A tumor of parafollicular C cells. May secrete calcitonin. Fifteen percent are familial or associated with multiple endocrine neoplasia (MEN) 2A or 2B.
Anaplastic: Undifferentiated. Has a poor prognosis; usually occurs in older patients.
Other: Metastases to thyroid (breast, kidney, melanoma, lung); lymphoma (1° or metastatic).
Approach:
If thyroid nodule palpable
GET TSH First.
If High TSH – suggests cold nodule. Get Thyroid Ultrasound to look for suspicious features. If no suspicious features, get free T4, TPO Antibodies and Rx as Hashimatos. If Suspicious features on ultrasound, get FNAC
If TSH low – suggests Hot nodule ( toxic adenoma) but not confirmative ( What if theres GRAVES and this is a cold nodule?) à so, get RAIU scan next à if COLD nodule get FNAC. If RAIU scan shows Hot nodule treat with I131 or follow up.
If TSH normal – get Ultrasound next. Do FNAC where indicated ( see below)
FNAC indicated if
Nodule > 10 mm in diameter
On ultrasound if nodule has suspicious features à hypoechoic, microcalcifications, irregular shape, blurred margin or increased vascularity
Cold nodules are more likely to be malignant when compared to hot nodules ( hot/ functioning nodule virtually rules out malignancy)
A negative FNAC does not rule out cancer completely. So, if clinical suspicion for cancer is high à consider surgical excision of the nodule. ( esply follicular adenoma)
Further Approach
If FNAC is benign
Cystic nodule – use percutaneous Ethanol injection to get rid of nodule
Solid Nodule – use suppressive therapy with levothyroxine if there are no contraindications ( Heart disease, old age). Suppressive therapy with LT4 aims to reduce TSH and there by, regress the nodule
If FNAC is malignant à SURGERY
If FNAC is follicular adenoma (benign) à get a thyroid scan if not already done à If this is hot/functioning nodule, it rules out malignancy – so, follow-up. If this is a cold nodule, a negative FNAC from one area may not rule out possibility of follicular carcinoma in follicular adenoma – so, do Surgery in those cases.
If FNAC is non-diagnostic à repeat FNAC