Thyroid adenoma is a benign nodular neoplasm of thyroid tissue. Thyroid adenoma may be asymptomatic or manifest signs of hyperthyroidism (weight loss, weakness, tachycardia, sweating, etc.), compression of the neck organs. Diagnosis of thyroid adenoma consists in ultrasound, hormonal studies (T3, T4, TSH, TG), X-ray of the esophagus, puncture biopsy of the gland and cytological examination of the material, scintigraphy. With adenoma, thyrostatic therapy with subsequent surgery (removal of the nodular formation of the thyroid gland, hemithyroidectomy) may be recommended or treatment with radioactive iodine.
D34 Benign neoplasm of the thyroid gland
Thyroid adenoma is a conditionally benign, encapsulated tumor originating from the thyroid epithelium and characterized by independent growth and functioning. Thyroid adenoma accounts for 45 to 75% of all thyroid nodules in endocrinology. The tumor develops 4 times more often in women; the average age of patients with adenoma is 45-55 years. Thyroid adenomas, depending on their hormonal activity, can occur against the background of an euthyroid condition or lead to the development of hyperthyroidism (thyrotoxicosis). Thyroid adenoma refers to tumors with potential malignancy, i.e. the possibility of transformation into thyroid cancer.
Causes of thyroid adenoma
The causes and mechanisms of thyroid adenoma are not clear enough. In the pathogenesis of this process, the role of hypersecretion of thyrotropin, violations of regional sympathetic innervation, mutation of the gene encoding the receptors of thyroid-stimulating hormone of the pituitary gland is not excluded.
Functioning thyroid adenomas often develop against the background of a pre-existing non-toxic node. It follows from this that risk factors may be living in areas with low iodine content in water and soil, the presence of nodular euthyroid goiter, hereditary predisposition. The starting point for the development of thyroid adenoma is often neck injuries (bruises, hematomas). Thyroid adenomas often develop against the background of autoimmune diseases.
Thyroid adenomas usually grow monocentrically, in the form of a single node, have a slow long-term development. Initially, the function of the adenoma does not disrupt the hormonal balance; the formation is reflected on the scintigrams in the form of a “cold” or “warm” node. As the size of the node increases and its functional activity increases, the secretion of TSH begins to be inhibited by the feedback mechanism.
The intact part of the thyroid tissue eventually atrophies and becomes non-functional, and scintigraphy of the thyroid gland reveals the accumulation of radioactive iodine in the area of a hyperfunctioning adenoma (“hot” node). At this time, the patient develops signs of thyrotoxicosis. Non-functioning thyroid adenomas are transformed into toxic ones in 10% of cases.
Depending on the morphological structure, there are follicular, papillary, oxyphilic, functioning, light-cell, etc. types of thyroid adenoma. The source of the development of adenomas are A- and B-follicular cells of the thyroid gland. The most common types of adenomas:
- Follicular. They are rounded encapsulated nodes, of a dense elastic consistency, with sufficient mobility. Among the euthyroid nodular formations of the gland, they make up 15-20%. Follicular formations include such varieties as colloidal (macrofollicular), microfollicular, fetal, trabecular (embryonic) thyroid adenoma.
- Papillary. Such thyroid adenomas have a cystic structure; papillary growths surrounded by brownish fluid are revealed inside the cysts.
- Functioning (toxic). These adenomas are accompanied by the development of Plummer’s disease – excessive production of thyroid hormones (T3 and T4), suppressing the secretion of thyroid-stimulating hormone by the pituitary gland. Clinically manifested by signs of hyperthyroidism.
- Oncocytic. Adenoma developing from B cells (oxyphilic adenoma from Gürtle-Askanazi cells, Langhans tumor) has the most aggressive course and in 10-35% of cases turns out to be malignant during histological examination.
Symptoms of thyroid adenoma
Non-functioning thyroid adenoma remains asymptomatic for a long time and is often detected by an endocrinologist during a routine medical examination or during an ultrasound of the thyroid gland. In this case, when palpating the neck, a solitary nodular formation of one of the thyroid lobes is detected: painless, mobile, dense or mildly elastic.
With an increase in the size of the thyroid adenoma, there may be a visible deformation of the neck, compression syndrome – a feeling of pressure, dysphagia, shortness of breath. A long course of adenoma may be accompanied by its calcification and ossification, the development of nodular toxic goiter, malignant degeneration, hemorrhage into the adenoma tissue, infection of the hematoma.
The development of toxic thyroid adenoma is accompanied by a decrease in body weight with a normal lifestyle and diet, sweating, tremor, fatigue during physical exertion, poor tolerance of heat and heat. Patients have increased emotional lability, irritability, anxiety, insomnia, tearfulness. Typically, the occurrence of sinus tachycardia or atrial fibrillation, angina attacks, arterial hypertension.
In the future, left ventricular and then right ventricular heart failure (edema, hepatomegaly) may join. Feverish conditions, disorders of the gastrointestinal tract, exophthalmos are often noted. With hyperthyroidism, due to an imbalance of sex hormones, men may develop gynecomastia and decreased potency; women – menstrual disorders and infertility.
In order to confirm and verify the diagnosis of thyroid adenoma, laboratory and instrumental studies are carried out:
- Ultrasound of the thyroid gland. The size, number, and localization of nodes are determined.
- Radioisotope scanning. It shows the degree of functional activity of the adenoma depending on the absorption of radioiode by the node (“cold”, “warm” or “hot” node).
- Hormone analysis. With toxic thyroid adenoma, the level of TSH in the blood serum is reduced; T3 and T4 are elevated or are at the upper limit of the norm. With non-functioning adenoma, hormone levels remain normal.
- Biochemical blood analysis. Hypolipidemia, impaired glucose tolerance is determined.
- Histological examination. The final confirmation of the diagnosis and determination of the morphological form of the adenoma is based on the results of a fine needle aspiration biopsy and a study of the cellular composition of the tumor. In 80% of cases, a biopsy makes it possible to differentiate adenoma and thyroid cancer.
When compression of neck structures is performed, radiography of the esophagus with barium is performed. In case of thyrotoxicosis, an examination of the heart (ECG, EchoCG), liver and kidneys (biochemical blood test, ultrasound) is performed. In the process of diagnosis, other thyroid lesions are excluded – nodular goiter, autoimmune thyroiditis, thyroid cancer.
Treatment of thyroid adenoma
Thyroid adenomas are subject to surgical removal. Conservative treatment is allowed only with colloidal adenoma, mainly during pregnancy, since this type of tumor is less likely to be malignized.
The operation should be performed against the background of an euthyroid condition, therefore, with thyrotoxicosis, preliminary drug treatment with thyrostatic drugs (carbimazole, thiamazole, propylthiouracil) is carried out. In the preoperative period, mental rest, a diet enriched with proteins and vitamins, full sleep, herbal medicine are recommended; it is forbidden to take sun baths and visit a solarium.
Upon reaching euthyroidism, the thyroid node is enucleated with an urgent histological examination of the adenoma. When a significant part of the thyroid gland is affected or malignized forms of adenoma, the scope of the operation is expanded to hemithyroidectomy, subtotal resection of the thyroid gland, or thyroidectomy.
In elderly patients or with contraindications to surgical treatment of thyroid adenoma, radioactive iodine therapy is used. In some cases, sclerosis of the adenomatous node by injection of ethyl alcohol is successful. This leads to the death of tumor cells and destruction of thyroid adenoma.
Timely comprehensive examination and individualized treatment of thyroid adenoma ensure complete recovery. After total removal of the thyroid gland, lifelong replacement therapy is necessary – the intake of thyroid hormones. After surgery, it is necessary to follow up with an endocrinologist, periodic monitoring of thyroid hormones, rejection of bad habits, avoidance of excessive insolation.