Congenital anomalies of the thyroid gland are a relatively common problem affecting approximately 1-3% of the general population. These anomalies can lead to a range of thyroid disorders, including hypothyroidism, hyperthyroidism, and goiters, and may require surgical intervention.
Surgical management of congenital anomalies of the thyroid gland can be complex and requires a good understanding of anatomy, surgical techniques, and postoperative care.
From the perspective of the NEET PG exam, congenital anomalies of the thyroid gland are an important topic that is commonly tested in the exams. Having a good understanding of this topic is essential in order to perform well.
In this blog, we have discussed congenital anomalies of thyroid in brief for NEET PG/NExT exam preparations. Read on.
THYROGLOSSAL CYST
Congenital condition, but age of presentation is 15-30yrs. Most common site: Subhyoid
Clinical features
Midline swelling in the anterior part of neck. Which moves with deglutition and moves up on protrusion of tongue
Complication
Infection of thyroglossal cyst leads to abscess formation; managed with Incision and drainage. Thyroglossal Fistula occurs as a complication of I/D. Therefore, it is an acquired condition. Thyroglossal cyst is congenital conditions. Thyroglossal cyst increases the risk for papillary Carcinoma Thyroid.
Treatment
Treatment of choice: Sistrunk Operation (En Bloc removal of central part or body of Hyoid bone with cyst)
ENDEMIC GOITER
5% people in population have goiter
RETROSTERNAL GOITER
AKA Substernal / Mediastinal goiter. >50% of Thyroid Tissue is located below the opening of thoracic cage. Mostly asymptomatic and diagnosed incidentally on radiological investigation
Clinical features
Dyspnea
Dysphasia
Hoarseness of voice
Dilated veins over Anterior Chest wall
Pemberton Sign is positive
Treatment
Thyroidectomy by cervical incision
Commonly used radioisotopes in thyroid disorders
I123 (Iodine 123)
Half-life 13 hours
Used for Diagnostic purpose only RAI (Radioactive Iodine) Scan
I131
Half-life 8 days
Used for Diagnostic and Therapeutic purpose
RAI scan and Ablation
I131
Emits β Rays (90%) and Y - Rays (10%)
Emits β Rays (90%)
Emits Y - Rays (10%)
β Rays mainly responsible for therapeutic effects
Depth of penetration of β Rays - 0.5 min
Y- Rays- Used in Tracer studies and responsible for side effects.
Absolute C/I for Radioactive Iodine Ablation
Pregnancy
Lactation
Radioactive iodine scan aka thyroid scan
Hot nodule: Increased uptake as compared to surrounding tissue- Risk of malignancy 1-3%
Cold Nodule: Decreased uptake as compared to surrounding tissue- Risk of malignancy 17-20%
In Graves’ Disease: In whole thyroid there is relatively increased RAI uptake
In Toxic MultiNodular Goiter: Certain nodules having increased uptake and certain nodules having decreased uptake i.e. both hot and cold nodules are present
In Thyroiditis: There is inflammation of thyroid. Therefore, decreased uptake of RAI i.e. <5% uptake of RAI
Types of thyroidectomy
Total thyroidectomy: Removal of all visible thyroid tissue
Hemithyroidectomy: Removal of one lobe with isthmus
Subtotal Thyroidectomy: Only 3-4 gm of thyroid tissue left in each lobe superiorly
Hartley Dunhill procedure: Modification of Subtotal Thyroidectomy 4-6 gm of tissue left in Single Lobe
Near Total thyroidectomy: Total less than 1 gm of tissue is left near/ adjacent to Recurrent Laryngeal Nerve at Ligament of Berry
Indications
HemiThyroidectomy: Performed in Benign disorder involving one lobe
Total Thyroidectomy: Performed in Thyroid Malignancy and benign disorders involving both lobes
Subtotal Thyroidectomy: Performed in Multinodular Goiter in Elderly
SOLITARY THYROID NODULE
Most common STN: Colloid Goiter > Follicular Adenoma
1st Investigation done in STN: TFT (TSH, T3, T4)
lOC for STN: FNAC
Limitations of FNAC in Solitary Thyroid Nodule
Follicular neoplasms: It cannot differentiate Follicular Adenoma from follicular Carcinoma. (Capsular/Follicular invasion not seen on FNAC). Riedel’s Thyroiditis: Whole thyroid is replaced by fibrous tissue
Thyroid Lymphoma: Any lymphoma Investigation of choice is biopsy. In All of the above limitations of FNAC: Investigation of choice is Biopsy
Most common Cause of Hypothyroidism worldwide: Hashimoto's Thyroiditis. Most common Cause of Hyperthyroidism worldwide: Grave's Disease
GRAVE'S DISEASE
Aka Diffuse Toxic Goiter.Associated with HLA-B8/DR-3. It is an Autoimmune disorder (autoimmune disorder are most commonly seen in females)
Due to increased Ab, there would be↑↑ T3 and↑↑ T4 and negative feedback causes ↓ TSH
↑↑ T3&T4 results in following clinical features
Thyrotoxicosis
Ophthalmopathy
Dermopathy: Pretibial myxedema because of deposition of glycosaminoglycan
Acropathy: Subperiosteal new bone formation
Gynecomastia
Clinical features
Sympathetic Stimulation S/S
Thyroid Stimulation S/S
Tachycardia
Palpitation
Excessive Sweating
Fine Tremors in Finger and Tongue
Mental irritation / Lack of Sleep.
Female Specific S/S
Amenorrhea
Abortions
Infertility
Children Specific S/S
Early Growth and Maturation
In young patients
CNS Symptoms are predominant
In Elderly
CVS Symptoms are predominant
↑ BMR causes ↑↑ Appetite → Weight loss
Excessive Sweating
Heat Intolerance
Diarrhea (Most common GI symptom)
In Thyroid gland
Thyroid Hyperactive: ↑↑ Radioactive Iodine Uptake
Thyroid Hyper vascular: Most prominent at upper pole-palpable thrill, audible Bruit, venous Hum
Diagnosis
Eye Signs present in patients of Hyperthyroidism are Diagnostic
Single Investigation that confirms diagnosis: Presence of autoantibodies
Management
For Sympathetic S/S 1st drug given: Propranolol
Antithyroid drugs: To control over production of T3 &T4
Antithyroid Drugs
Methimazole: Diagnosis of choice in Graves (S/E: ↑↑ risk of Choanal Atresia, Agranulocytosis and Aplasia Cutis. Therefore, not safe in pregnancy)
Carbimazole: Diagnosis of choice in pregnancy
Propylthiouracil: Diagnosis of choice in Thyrotoxic crisis as it Blocks Peripheral Conversion (S/E: ↑↑ risk of Hepatic failure especially in females and children)
The drugs are given to patient to make the patient euthyroid before surgery
Treatment of choice in Grave's: Total Thyroidectomy
RAI Ablation
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