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Adenoma of the Thyroid

Endocrine system

Adenoma of the Thyroid
A thyroid adenoma is a benign, encapsulated tumor arising from follicular cells of the thyroid gland. It is usually solitary and non-functional, although some adenomas can secrete thyroid hormones, leading to hyperthyroidism (toxic adenoma).

Types of Thyroid Adenomas:
1. Follicular Adenoma:
o The most common type, characterized by a proliferation of follicular cells forming small or large follicles.
2. Hurthle Cell Adenoma:
o Composed of Hurthle cells (large, eosinophilic cells with granular cytoplasm).
3. Toxic Adenoma:
o A hyperfunctioning adenoma that produces excess thyroid hormones, causing hyperthyroidism.

Clinical Features:
• Thyroid Nodule:
o A painless, palpable mass in the neck.
• Hyperthyroid Symptoms (in toxic adenomas):
o Weight loss, palpitations, tremors, heat intolerance, and increased appetite.
• Compression Symptoms (rare):
o Dysphagia or hoarseness if the nodule is large enough to compress surrounding structures.

Gross Appearance:
• Size and Shape:
o Solitary, well-circumscribed, and encapsulated nodule.
• Capsule:
o The tumor is surrounded by a thin, fibrous capsule.
• Colour and Texture:
o Tan to brown, solid cut surface.
o May have areas of cystic change, hemorrhage, or fibrosis. 








Microscopic (Histological) Features:
1. Follicular Architecture:
o Uniform follicles filled with colloid, lined by a single layer of cuboidal cells.
2. Capsule:
o Well-defined fibrous capsule, with no capsular or vascular invasion (a key feature distinguishing it from follicular carcinoma).
3. Hurthle Cell Adenoma:
o Cells have abundant eosinophilic, granular cytoplasm.
4. Cystic Changes and Hemorrhage:
o Occasionally seen but not predominant.
5. Mitotic Activity:
o Low to absent, supporting its benign nature.







Diagnosis:
• Clinical Examination:
o Detection of a solitary thyroid nodule.
• Ultrasound:
o Helps differentiate between benign and suspicious nodules.
o Features of a benign adenoma: well-defined margins, hyperechoic texture.
• Fine-Needle Aspiration (FNA):
o Cytology may suggest a follicular lesion, but cannot distinguish adenoma from carcinoma.
• Surgical Excision and Histopathology:
o Required for definitive diagnosis to rule out malignancy.
• Thyroid Function Tests:
o Usually normal, except in toxic adenomas (elevated T3 and T4, suppressed TSH).
• Radioisotope Scan (for toxic adenoma):
o "Hot" nodule on scan (increased uptake).


Management:
• Observation:
o For small, asymptomatic nodules with benign cytological features.
• Surgery:
o Lobectomy or thyroidectomy if there is suspicion of malignancy, compression symptoms, or cosmetic concerns.
• Radioactive Iodine Therapy:
o An option for toxic adenomas.
• Thyroid Hormone Suppression Therapy:
o Rarely used, but may help shrink the nodule.

Prognosis:
• Excellent: As adenomas are benign, surgical removal typically results in a complete cure.
• Potential for Malignancy: Although adenomas themselves are not cancerous, follicular adenomas require careful evaluation to exclude follicular carcinoma.




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