True statement regarding follicular cell carcinoma of thyroid: (D. REPEAT 2013)

Ref: Robbins Pathologic Basis of Disease, 8th edition. Pages 1120-24 and Schwartz SurgeryExplanation:Multifocal lesions are seen in Papillary thyroid carcinoma.Follicular cancer can be diagnosed ONLY by histopathological examination.FNAC cannot differentiate between follicular adenoma and carcinoma.FOLLICULAR CANCERSecond most common thyroid malignancy (MC- Papillary).Clinical Features40-60 years.Female: Male =3:1.Most commonly presents as asymptomatic thyroid nodule.TSH depe ndent.Can be associated with Multinodular Goitre in 10%.Hoarseness and firm fixation of the mass on clinical evaluation suggest advanced disease and a poor prognosis, these circumstances are again found in a minority of cases.Associated with iodine deficiency.Not strongly associated with radiation exposure.A subty pe of follicular cancer, known as Hurthle cell carcinoma, consists of oxyphilic cells and tends to occur in older patients, usually 60 to 75 years of age.PathologyHistologic diagnosis of follicular cancer depends on the demonstration of follicular cells occupying abnormal positions, including capsular, lymphatic and vascular invasion.If these findings are absent, the diagnosis is benign follicular adenoma.Using these criteria, two types of follicular carcinoma are usually described, minimally invasive and widely invasive.Lymph node involvement is unusual, occurs in < 10% of cases.Typically spreads via hematogenous routes, which occurs in 10% to 15% of cases.The most common sites for metastatic deposits are lytic bone lesions and lung.Prognostic FactorsPrognosis is less favorable for follicular than for papillary cancer.Best prognosis in young patients w ith limited capsular or vascular invasion.Age is the most important predictor of survival, with a 95% 10-year survival in those younger than 40 years and an 80% 10-year survival between 40 and 60 years.Follicular cancers in older patients also are less likely to respond to radioiodine therapy.Size of the primary tumor is also an important prognostic factor.DiagnosisOnly on Histopathological examination.The distinction betw een a follicular carcinoma and an adenoma can only be made by histological examination.o Invasion of the capsule or of pericapsitlar blood vessels is necessary to diagnose carcinoma which can be demonstrated only by histopathology.o Intraoperative frozen section is not useful.MANAGEMENTBased on size of the lesionIf Size <2cm - Hemithyroidectomy followed by Histopathological examination.If HPE shows:Adenoma - No further treatment.Carcinoma - Proceed with total thyroidectomy.Size >2 cm - Total thyroidectomy.Adjuvant TherapyRadioiodine ablation w ith iodine 131.Long-term monitoring of thyroglobulin.