Patients with thyroid carcinoma will have an enlargement of the thyroid gland due to the presence of a nodule in either or both thyroid lobes. They can be symptomatic with either hypothyroid or hyperthyroid characteristics. 

Ultrasound imaging and ultrasound-guided fine needle aspiration or core biopsy are used to diagnose primary thyroid carcinoma. Ultrasound of primary thyroid cancer usually shows solid hypoechoic nodules with micro-calcification, poorly defined margins, and vascular patterns with the dominant intranodular flow, as opposed to perinodular.[14]  CT and MRI are used to evaluate extrathyroidal tumor extension but not for the thyroid nodule itself.[14] The sample received from fine needle aspiration or core biopsy is then viewed under the microscope for confirmation. Follicular thyroid carcinoma is diagnosed based on pathologic confirmation of follicular cells that do not have the nuclear atypia seen in papillary thyroid cancer including capsular and vascular invasion. Therefore, the basis of evaluation is mainly on the histologic findings of the pathologist. Thyroid carcinoma is classified to be follicular if invasive and contains mostly follicles. Histologic findings of pathologist have been reported to vary leading to controversy in the classification of follicular thyroid carcinoma.[15]

The treatment and management of follicular thyroid carcinoma depend on the stage at presentation. Follicular thyroid carcinoma with minimally invasive characteristics is treated with thyroid lobectomy and isthmectomy, but for invasive follicular carcinoma, total thyroidectomy, radioiodine ablation, thyrotropin suppressing medications are recommended.[16] A study reported a 2.1 fold increase of follicular thyroid cancer recurrence in those who did not undergo radioiodine ablation compared to those who did, which is why the standard treatment recommendation is total thyroidectomy followed by radioiodine radiation.[17] For patients with metastasis to bones and soft tissue, either radiotherapy or chemotherapy or both are indicated after the total thyroidectomy. Chemotherapy that has been reported to control tumor progression and prolong progression-free survival includes tyrosine kinase inhibitor such as sorafenib, lenvatinib, vandetanib, and cabozantinib.[18] Thyroglobulin levels are measured to monitor for recurrence. 

Differential diagnosis of follicular thyroid carcinoma includes a follicular variant of papillary thyroid carcinoma, papillary thyroid carcinoma, and follicular adenoma. There is a controversy with the pathologic diagnosis of follicular thyroid carcinoma and identification could differ from one pathologist to the other. This controversy is due to two factors including the degree of nuclear atypia and the degree of capsular or vascular invasion.[15]

The TNM staging system is used to classify differentiated thyroid carcinoma. The T describes the size of the tumor. Tx indicates that primary tumor cannot be assessed, T0 means tumor not palpable, T1 means less than 1cm, T2 means 1 to 4cm, T3 indicates greater than 4cm, and T4 means any tumor size with extrapyramidal invasion. The N signifies lymph node involvement. Nx signifies regional adenopathy is not assessable, NO means no palpable cervical adenopathy, N1 means ipsilateral cervical adenopathy, N2 means contralateral or bilateral cervical adenopathy, N3 means fixed cervical nodes. M means metastases with M0 indicative of no distant metastases and M means distant metastases. Follicular thyroid carcinoma classifies into stages from stage I through stage IV. Stage I under 45 years old is any T, N, and M0, and over 45-years-old is T1, N0, M0; for stage II under 45 years old is any T, N and M1 and over 45 years old is T2, N0, M0; stage III described over 45 years of age with T4, N0, MO, and stage IV describes any T, N, M1.[13]

The thyroid cancer death rate has remained steady even with the increase in the incidence. It is one of the lowest mortality cancers in the United States. In 2017, an estimated 2010 death occurred due to thyroid cancer compared to more than 150000 deaths from lung cancer.[12] Follicular thyroid cancer has a worse prognosis compared to papillary thyroid cancer due to its higher incidence of distant metastasis and patients presenting with more advanced stage disease.[12] Even though follicular thyroid cancers have distant metastasis, metastasis to lymph nodes is uncommon, and occurrence is estimated to be fewer than 10%.[19] On the other hand, some studies reported that there is no prognostic difference between follicular thyroid cancer and papillary thyroid cancer when controlling for factors such as age and sex.[15] The overall 10-year survival of follicular cancer depends on the level of invasiveness. For minimally invasive cancers, 10-year survival is reported to be 98%, and for invasive follicular cancer, it is 80%.[4] Some studies also report that the survival rate ranges from 46% to 97% also depending on the degree of capsular or vascular invasion.[15] The mortality rate of follicular thyroid carcinoma range from 5 to 15% and those with capsular invasive characteristics have an overall worse prognosis compared to those without invasion.[20]

The complication involved in follicular thyroid cancer is metastasis. Studies have reported metastasis to mostly to bones, lungs and lymph nodes. In a study done by Parasmeswaran et al. (2017), they found that 42% of their subjects had metastasis to the bones, 33% to the lungs and 8% to the lymph nodes.[3] The incidence of distance metastasis in follicular thyroid carcinoma is estimated to be 6 to 20%.[21]

Other complications correlate with surgery. The external and recurrent laryngeal nerves are near the thyroid gland, and can mistakenly get damaged during surgery or resected due to invasion.[22] This will cause hoarseness of patient voice. There are also reports of hematoma and keloid formation in some patients after the surgery.[22]

Because the patient is undergoing total thyroidectomy, hypothyroidism will develop, and patients will require thyroxin replacement therapy. 

Although the prognosis of thyroid cancer has been reported to be good compared to other forms of cancer, the mention of the word "cancer" will still be a concern for most patients. For instance, most patients will still opt for surgical removal of the thyroid even if they have the non-invasive follicular thyroid cancer that can be followed due to its slow growth. Patients and their physicians need to work together to decide the best treatment option. Knowledge gained by patients will enable them to make better decisions about their health.

The incidence of thyroid cancer has increased over the past few decades which is attributed to over-diagnoses.[23] As a result in 2017, USPTF recommends against the screening of thyroid cancer with either neck palpation or ultrasound in asymptomatic patients.[12]  In 2015, American thyroid association recommended active surveillance of low-risk thyroid carcinomas with serial ultrasound and that not all patients require surgery. Also, the organization released guidelines in 2015, not to biopsy thyroid nodules that are less than 1cm.[12] Physicians including nurse practitioners and other healthcare professionals should be aware of these guidelines; this will prevent potential harm to patient from overtreatment of low-risk thyroid cancers and appropriate treatment to those patients who have high-risk disease. Reportedly, the overall cost of thyroid cancer in 2019 would be 18 to 21 billion dollars due to surgery cost.[12] Not all thyroid neoplasms require surgery and physicians should keep this in mind when managing patients who develop thyroid cancer.