وصف
Thyroid carcinoma is a type of cancer that develops in the thyroid gland, which is located in the neck and produces hormones that regulate metabolism. Total thyroidectomy, where the entire gland is removed, is typically recommended for papillary and follicular thyroid cancer. Lymph node dissection may also be performed to remove any cancerous lymph nodes in the neck. Advances in surgical techniques, such as the use of minimally invasive procedures, have improved outcomes for patients with thyroid carcinoma.
ملخص
- Thyroid nodules are a common clinical problem, and while many are benign, differentiated thyroid cancer is increasingly prevalent. Although thyroid swelling is more common in females, malignancy is more likely in males. Common causes of thyroid swelling include benign adenomas or colloid cysts, inflammatory or infectious conditions like thyroiditis or tuberculosis, and neoplastic nodules of thyroid follicular, parafollicular, or lymphoid origin (papillary, follicular, medullary carcinoma, and lymphoma).
- Benign and malignant thyroid conditions can present similarly with painless swelling, but malignant nodules are often firm to hard and may be associated with neck nodes. Metastatic presentation can also occur with fractures or lung nodules. A recent or long-standing history of rapid swelling growth suggests a potential malignant transformation. Hoarseness due to nerve involvement is a late symptom often seen in aggressive cancers.
- Initial investigations include a thyroid profile and neck ultrasound to assess thyroid function and nodule characteristics. Hyperthyroidism is less likely to be associated with malignancy, and FNAC should be delayed until the patient is euthyroid. Ultrasound can differentiate between benign and malignant nodules based on consistency, echogenicity, shape, margins, extra-thyroid extension, and microcalcifications, utilizing the TIRADS classification for standardized reporting.
- In hyperthyroid cases, iodine scintigraphy is performed to differentiate between diffuse and focal uptake, guiding treatment decisions. Fine Needle Aspiration Cytology (FNAC) is crucial for guiding surgery, with results standardized using the Bethesda system (Bethesda 1-6) to categorize nodules from non-diagnostic to malignant. Bethesda 3 and 4 represent indeterminate risks, with follicular adenoma and carcinoma differentiation not possible via FNAC.
- Further imaging with CT or MRI is necessary when retropharyngeal extension or fixed masses are present to assess involvement of adjacent structures. PET/CT is generally reserved for suspected anaplastic or medullary thyroid carcinoma. Surgical management options include hemithyroidectomy or total thyroidectomy, with no role for nodulectomy or near-total thyroidectomy in malignancy.
- Neck node clearance (level 6 or lateral compartments 2-5) is performed based on node involvement, with unilateral dissection typically done for papillary and follicular carcinoma. Tracheal resection or laryngectomy may be required in cases of tracheal or laryngeal involvement. Surgical steps involve a skin crease incision, flap elevation, strap muscle separation, and ligation of thyroid pedicles close to the gland to preserve parathyroid blood supply and the recurrent laryngeal nerve.
- Adjuvant therapy, primarily radioactive iodine (RAI), is often administered after total thyroidectomy to ablate residual thyroid tissue or microscopic metastases. Recombinant TSH can be used to reduce the duration of hypothyroidism required for RAI therapy. External beam radiation therapy is considered for residual tissue or in cases of medullary carcinoma.
- Follow-up involves thyroid hormone suppression with levothyroxine, with dosages adjusted to suppress TSH. Regular monitoring includes serum TSH, thyroglobulin (TG) as a biomarker, antithyroglobulin antibodies (TgAb), and ultrasound, with frequency depending on the stage of disease. Differentiated thyroid cancers have excellent prognoses, while anaplastic carcinoma carries a poor prognosis. Factors associated with poorer prognosis include extremes of age, male sex, familial thyroid cancer, extra-thyroid extension, vascular invasion, lymph node metastasis, and specific tumor subtypes.
- Thyroglobulin-elevated negative iodine scintigraphy (TENIS) syndrome refers to elevated thyroglobulin without iodine uptake, indicating de-differentiation. PET scans are useful in these cases due to increased glucose uptake by de-differentiated cells. Minimally invasive approaches without incisions (laparoscopic/robotic) exist but are largely limited to benign cases due to limited dissection in cases of malignancy.
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