Thyroid Cancer, Follicular

• • History of radiation to the neck in some patients

  • Painless or enlarging nodule, dysphagia, or hoarseness

  • Firm or hard, fixed thyroid nodule; cervical lymphadenopathy

  • Normal thyroid function; nodule stippled with calcium (x-ray), solid (US), cold (radioiodine scan), positive or suspicious cytologic studies

  • Family history of thyroid cancer

Epidemiology

• • Accounts for approximately 10% of all malignant thyroid tumors

  • Appears later in life than papillary thyroid cancers, with peak incidence in fifth decade

  • 3 times more common in women than in men

  • Incidence decreasing as the intake of dietary iodine has increased

  • 80% of encapsulated follicular tumors > 4 cm are malignant

Symptoms and Signs

• • Thyroid nodule: Hard, rubbery, or soft

  • Enlarged or hard cervical lymph nodes

  • Pain in the thyroid or paralaryngeal neck

  • Hoarseness

  • Dyspnea

  • Stridor

  • Dysphagia

Laboratory Findings

• • Normal thyroid-stimulating hormone (TSH) levels

Imaging Findings

• • US: Solid or cystic nodule

  • Radioiodine scans: Nonfunctioning (cold)

• • Fine-needle aspiration is unable to reliably differentiate the atypical cells of invasive follicular adenocarcinoma from its counterpart benign adenoma

  • Follicular carcinoma distinguished from follicular adenoma by capsular and vascular invasion

  • 7% spread lymphatically; most spread hematogenously (to lungs, skeleton, liver, and CNS)

  • Skeletal metastases may appear 10 years after resection of primary tumor

Rule Out

• • Concurrent hyperparathyroidism (so that it can be treated at the same operation if necessary)

• • Complete history and physical exam, with attention to risk factors, family history, palpable characteristics of the nodule or lymphadenopathy

  • Measurement of serum TSH and calcium

  • Cervical ultrasound to assess the thyroid gland and cervical adenopathy

  • Fine-needle aspiration biopsy

• • Operative removal

  • External beam radiation may palliate nonresectable metastases that are resistant to radioiodine

Surgery

Indications

• • All follicular thyroid cancers should be excised

  • Imageable or palpable nodal recurrences

Medications

• • Suppressive doses of thyroid hormone after thyroid ablation or thyroidectomy

  • Radioactive iodine therapy for remnant, recurrent, or metastatic disease

Treatment Monitoring

• • Semiannual or yearly neck exams, serum thyroglobulin, thyroglobulin antibodies, and whole body radioiodine scan

Complications

• • Neck hematoma

  • Superior laryngeal nerve injury

  • Recurrent laryngeal nerve injury

  • Transient or permanent hypoparathyroidism

  • Wound infection

Prognosis

• • Worse prognosis predicted by extensive angioinvasion, older age, and presence of distant metastases

  • 10-year survival nearly 100% with only microinvasion

  • 10-year survival about 72% with angioinvasion

References