Exam Essentials: Breast & Endocrine Image Discussion

TDLU

TDLU stands for terminal duct lobular unit. It is the intralobular portion of the terminal duct. Terminal duct lobular unit is the most active part of the breast tissue and responds to all hormones like estrogen, progesterone, prolactin, etc.

Most breast cancers and most breast diseases arise from the terminal duct lobular unit.

 50% of the terminal duct lobular unit is in the upper outer quadrant, and 20% of the terminal duct lobular unit is in the Central quadrant. Maximum breast cancer arises from the upper outer

quadrant because of the maximum number of the terminal duct lobular unit.

Axillary Lymph Nodes Levels

Levels: Divided in realtion to the Pectoralis minor Muscle.

Level 1: Lateral to lateral border of pectoralis minor. It includes the anterior, posterior, and lateral groups of lymph nodes.

Level 2: Lymph nodes include the Central and Rotters group of lymph nodes. The lymph nodes lie between the medial and lateral border of the pectoralis minor.

Level 3: Any lymph nodes that lie medial to the medial border of the pectoralis minor. Apical or infraclavicular lymph nodes form the level 3 level.

Mastitis and Breast Abscess

Mastitis and breast abscesses, can be lactational or nonlactational. 90% of breast abscesses are lactational. Non-lactational mastitis or breast abscesses, are commonly associated with duct ectasia. When breast abscesses occur associated with duct ectasia and non-lactational breast abscesses, they are more commonly subareolar breast abscesses.

Histology of Thyroid Gland

The thyroid gland is made up of lobes, and lobes are made of lobules. Lobules are called the functional unit of the thyroid gland.Every lobule is supplied by single arteriole. Lobules are made of follicles and around 25-40 follicles in each lobule. The follicles are lined by single-layered flattened cuboidal cells in resting state. The activity of the thyroid gland increases, and the height of the epithelial cells increases. In Hyperthyroidism Epithelial lining becomes High (tall) columnar epithelium. In center of the follicle contain the colloid which stores the T3 and T4 bound to the protein Thyroglobulin.

Lingual Thyroid

It is an undescended thyroid located at the base of tongue . Due to inadequate production of thyroid hormones there is increased levels of TSH, it leads to the increase size of the thyroid gland which results in swelling at the base of the tongue.

Non-Toxic Goiters

Non-toxic goiters can be of two types. They can be diffused goiters or multinodular goiters. Diffuse goiters is an enlarged thyroid gland with no or scattered sub-centimetric nodules within the gland. Multinodular goiter is an enlarged thyroid gland with more than one nodule identified, clinically, radiologically, or surgically.

Pretibial Myxedema

Graves disease can be associated with certain skin changes or be dermatopathy, and one of the most common skin changes associated with grave disease is pretibial myxedema. Pretibial myxedema is the thickening of the skin due to the deposition of mucin-like substances. Pretibial, as the name suggests, is most commonly seen in the lower limbs, in the legs, in the tibia, or over the feet.

When it occurs as a bilaterally symmetrical condition and produces a non-pitting edema. It can occur in different forms, like a nodular form, a localized nodular form of pretibial myxedema, a horny form, or a sheet-like localized pretibial myxedema. Patients with grave disease can have thyroid acropachy.

Also Read: Glucagonoma: Symptoms, Diagnosis, And Treatment

Thyroid Acropachy

Thyroid acropachy is increased subperiosteal bone formation with enlargement of the digits and digital clubbing is called thyroid acropachy.

Beahr's Triangle

It is a triangle which is very important in identification of RLN.

Boundaries are

• Common carotid artery.
• Inferior thyroid artery
• Recurrent laryngeal nerve

Potential Sites for Recurrent Laryngeal Nerve Injury

1. Ligament of Berry- Most common site.
2. In relation to the Inferior Thyroid artery and branches
3. In the thoracic inlet at the tracheoesophageal groove.

Recurrent laryngeal nerve supplies intrinsic Muscles of the larynx and sensory supply below the vocal cords. Due to RLN injury mixed pathology in the larynx is seen. Most common Manifestation-Paralysis of the vocal cord on affected side.

Hope you found this blog helpful for your NEET SS Surgery Breast and endocrine preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.