Thyroid adenoma

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

Thyroid adenoma is a benign tumor of the thyroid gland. Thyroid adenoma was first discovered by Fabricius, in 1619 when he described that thyroid enlargement causes midline neck swelling. Thyroid adenoma may be classified according to the histology into 3 subtypes/groups follicular adenoma, papillary adenoma, and signet cell adenoma. Thyroid adenoma arises from epithelial cells of thyroid gland, that are normally involved in secretion of thyroxine hormone. The most common gene involved in the pathogenesis of thyroid adenoma is THADA gene. Common causes of thyroid adenoma include iodine deficiency, chronic inflammation, and genetic mutation of THADA gene. Thyroid adenoma must be differentiated from other thyroid disorders such as multinodular goiter, grave’s disease, Hashimoto’s disease, medullary cell carcinoma, De Quervain’s thyroiditis, thyroid lymphoma, and acute suppurative thyroiditis. The incidence of thyroid adenoma is estimated to be 9 million cases annually in United States. Females are more commonly affected with thyroid adenoma than males. Common risk factors in the development of thyroid adenoma are family history of thyroid adenoma, exposure to radiation, lack of iodine in diet, smoking, and Hashimoto’s thyroiditis. Depending on the extent of the tumor at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as excellent. The hallmark of thyroid adenoma is swelling in front of the neck. A positive history of radiation exposure and family history of thyroid adenoma is suggestive of thyroid adenoma. The most common symptoms thyroid adenoma include cough and hoarseness of voice. On ultrasound, thyroid adenoma is characterized by halo sign or smooth margin of thyroid, hyperechoic nodules, and normal reactive cervical nodes. Fine needle aspiration biopsy may be helpful in diagnosis of thyroid adenoma. Findings on fine needle aspiration biopsy suggestive of thyroid adenoma include cystic changes, fibrosis, and areas of hemorrhage. The mainstay of therapy for thyroid adenoma is supportive therapy and regular monitoring.

Thyroid adenoma was first discovered by Fabricius, in 1619 when he described that thyroid enlargement causes midline neck swelling.

Thyroid adenoma may be classified according to the histology into 3 subtypes/groups follicular adenoma, papillary adenoma, and signet cell adenoma.

Thyroid adenoma arises from epithelial cells of thyroid gland, that are normally involved in secretion of thyroxine hormone. The most common gene involved in the pathogenesis of thyroid adenoma is THADA gene.

Common causes of thyroid adenoma include iodine deficiency, chronic inflammation, and genetic mutation of THADA gene.

Thyroid adenoma must be differentiated from other thyroid disorders such as multinodular goiter, grave’s disease, Hashimoto’s disease, medullary cell carcinoma, De Quervain’s thyroiditis, thyroid lymphoma, and acute suppurative thyroiditis.

The incidence of thyroid adenoma is estimated to be 9 million cases annually in United States. Females are more commonly affected with thyroid adenoma than males.

Common risk factors in the development of thyroid adenoma are family history of thyroid adenoma, exposure to radiation, lack of iodine in diet, smoking, and Hashimoto’s thyroiditis.

Depending on the extent of the tumor at the time of diagnosis, the prognosis of thyroid adenoma may vary. However, the prognosis is generally regarded as excellent. Common complications of thyroid adenoma include hyperthyroidism,thyrotoxicosis, hemorrhage, thyroid cyst, and superior vena cava obstruction.

There is no single diagnostic study of choice for the diagnosis of thyroid adenoma, but thyroid nodules can be diagnosed based on an ultrasound examination of the neck, a screening serum TSH level, and fine needle aspiration biopsy.

The hallmark of thyroid adenoma is swelling infront of the neck. A positive history of radiation exposure and family history of thyroid adenoma is suggestive of thyroid adenoma. The most common symptoms thyroid adenoma include cough and hoarseness of voice.

Patients with thyroid adenoma usually appear normal. Physical examination of patients with thyroid adenoma is usually remarkable for solitary, non-tender nodule in the midline of neck, which is smooth, soft, and mobile.

Laboratory findings consistent with the diagnosis of thyroid adenoma include decreased thyroid stimulating hormone, elevated calcitonin, and decreased calcium.

On ultrasound, thyroid adenoma is characterized by halo sign or smooth margin of thyroid, hyperechoic nodules, and normal reactive cervical nodes.

Other diagnostic studies for thyroid adenoma include thyroid scan, which demonstrates hot, cold, and functioning nodule.

Fine needle aspiration biopsy may be helpful in diagnosis of thyroid adenoma. Findings on fine needle aspiration biopsy suggestive of thyroid adenoma include cystic changes, fibrosis, and areas of hemorrhage.

The mainstay of therapy for thyroid adenoma is supportive therapy and regular monitoring.

Thyroid lobectomy is recommended for all patients who develop pressure symptoms of thyroid adenoma.

There is no established method for prevention of thyroid adenoma.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Roukoz A. Karam, M.D.[2]

There is limited information about the historical perspective of thyroid adenoma.

There is limited information about the historical perspective of thyroid adenoma.

For more information about the history of thyroid nodules click here.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Roukoz A. Karam, M.D.[2]

Thyroid adenoma may be classified based on FNA cytology into 6 groups include macrofollicular, adenomatoid, colloid adenomas, nodular goiter, lymphocytic thyroiditis and granulomatous thyroiditis.

• Thyroid adenoma may be classified based on Fine needle aspiration (FNA) cytology into 6 groups (known as The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC)) :^[1]
  • Macrofollicular
  • Adenomatoid/hyperplastic nodules
  • Colloid adenomas
  • Nodular goiter
  • Lymphocytic thyroiditis
  • Granulomatous thyroiditis

• For information on the classification of thyroid nodules, click here.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

Thyroid adenoma arises from the epithelial cells of the thyroid gland, which are normally involved in secretion of thyroxine hormone. The most common gene involved in the pathogenesis of thyroid adenoma is THADA gene.

Thyroid adenoma are lumps which commonly arise within an otherwise normal thyroid gland. They indicate a thyroid neoplasm.^[1]

• Sometimes a thyroid nodule presents as a fluid-filled cavity called a thyroid cyst. Often, solid components are mixed with the fluid. Thyroid cysts most commonly result from degenerating thyroid adenomas, which are benign, but they occasionally contain malignant solid components.
• Thyroid adenoma may be clinically silent, or it may be a “functional” tumor, producing excessive thyroid hormone. In this case, it may result in symptomatic hyperthyroidism, and may be referred to as a toxic thyroid adenoma.

Colloid nodules are non-neoplastic benign nodules occurring within the thyroid gland. They form the vast majority of nodular thyroid disease. Colloid nodules are composed of irregularly enlarged follicles containing abundant colloid. Some colloid nodules can be cystic (cystic colloid nodule), and may contain areas of necrosis, hemorrhage, and calcification. Colloid nodules may be single or multiple and can vary considerably in size.^[2]

• The target gene associated with thyroid adenoma has been identified and referred to as thyroid adenoma associated (THADA) gene.^[3][4]
• In thyroid adenomas, protein associated with THADA was frequently found to be truncated.
• While competing with the full-length protein translated from the normal allele of THADA, the altered protein derived from the truncated gene might lead to an impaired induction of apoptosis, and subsequently give rise to an increased cell proliferation leading to benign thyroid tumors with 2p21 translocations, without significant changes of the expression level.

• Hyperthyroidism
• Multinodular goiter

Thyroid follicular adenoma ranges in diameter from 3 cm on an average, but sometimes is larger (up to 10 cm) or smaller. The typical thyroid adenoma is a solitary, spherical, and encapsulated lesion that is well demarcated from the surrounding parenchyma.^[5]The color ranges from gray-white to red-brown, depending upon:

1. The cellularity of the adenoma
2. The colloid content

• Areas of hemorrhage, fibrosis, calcification, and cystic change similar to what is found in multinodular goiters, are common in thyroid (follicular) adenoma, particularly in larger lesions.
• Encapsulated tumors without evidence of infiltration may be found.
• Colloid nodules are distinguished by an apparently gelatinous mass of colloid both surrounding and contained within follicular cells. Colloid nodules are not surrounded by a fibrous capsule of compressed tissue. However, they are surrounded by flattened epithelial cells.^[6] Both the number of cells and the type of colloid may vary considerably.^[7]

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Roukoz A. Karam, M.D.[2]

Thyroid nodule may be caused by multinodular (sporadic) goiter, Hashimoto’s thyroiditis, cysts, Hurthle cell adenomas, follicular, and macrofollicular or microfollicular adenomas.

Common causes of thyroid adenoma include:^[1][2]

• Multinodular goiter
• Hashimoto’s thyroiditis
• Cysts
• Follicular adenomas
• Macrofollicular adenomas
• Microfollicular or cellular adenomas
• Hurthle cell adenomas

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

Thyroid adenoma must be differentiated from other thyroid disorders such as multinodular goiter, grave’s disease, Hashimoto’s disease, medullary thyroid carcinoma, De Quervain’s thyroiditis, thyroid lymphoma, and acute suppurative thyroiditis.

• The table below summarizes the findings that differentiate thyroid adenoma from other conditions that cause neck swelling.^[1]

• Thyroid adenoma must be differentiated from other causes of hyperthyroidism such as Grave’s disease and toxic nodular goiter.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2] Roukoz A. Karam, M.D.[3]

The incidence of thyroid adenoma is estimated to be 9 million cases annually in the United States. Females are more commonly affected with thyroid adenoma than males.

• The incidence of thyroid adenoma is approximately 3000 per 100,000 individuals in the United States.^[1][2]

• Thyroid adenoma commonly affects individuals older than 50 years of age.

• Females are more commonly affected by thyroid adenoma than males. The female to males ratio is approximately 6 to 1.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

There are no established risk factors for thyroid adenoma.

• There are no established risk factors for developing thyroid adenoma.
• For more information about risk factors of thyroid nodules, click here.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]

Depending on the extent of the tumor at the time of diagnosis, the prognosis of thyroid adenoma may vary. However, the prognosis is generally regarded as excellent. Common complications of thyroid adenoma include hyperthyroidism, thyrotoxicosis, hemorrhage, thyroid cyst, and superior vena cava obstruction.

• Thyroid adenoma is usually a slow growing tumor which has limited growth and indolent behavior.^[1]

• Common complications of thyroid adenoma include:^[2]

• Hyperthyroidism
• Thyrotoxicosis
• Hemorrhage
• Thyroid cyst
• Thyroid cancer
• Dyspnea
• Stridor
• Dysphagia
• Superior vena cava obstruction

• Thyroid adenoma is a benign tumor and has excellent prognosis.^[3]

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