Breast Development:

• The milk line forms at 5 week of gestation and courses from axilla to groin. Normal breasts then form in the prepectoral region at the 4th and 5th intercostal space. The ectodermal layer then penetrates the mesoderm after there has been regression of milk  line. 
• Supporting connective tissue forms from surrounding mesenchyme.
• Estrogen is the primary hormone promoting development of breast epithelium and ductal tissue
• Progesterone acts in combination with estrogen to regulate breast development

Breast Anatomy:

• Sensation to the nipple areolar complex comes mainly from the lateral cutaneous branch of the fourth intercostal nerve.
• Blood supply to the breasts is via the internal thoracic or mammary perforators, lateral thoracic vessels, thoracoacromial vessels (preserved in subpectoral placement). In breast augmentation the internal mammary vessels are divided in both subglandular and subpectoral implant placement. The thoracoacromial vessels are preserved in subglandular implant placement. 
• Blood supply to the nipple areolar complex is from perforators of the internal mammary artery.
• Breast ptosis occurs through a combination of atrophy of the breast, loss of elasticity of the skin envelope, and attenuation of cooper’s ligaments.

Anomalies of breast development:

• Amastia: breast and nipple are absent
• Amazia: absence of breast (nipple is present)
• Athelia: absence of nipple
• Poland syndrome: abnormality of pectoralis muscle and associated ipsilateral limb hypoplasia
• Pectus deformities: alteration in appearance of sternum and costal attachments
• Anterior Thoracic Hypoplasia: presents as unilateral sunken anterior chest wall, hypoplasia of the breast, superiorly placed nipple areolar complex, normal pectoralis muscle, and normal sternum
• Tuberous Breast deformity: presents as hypoplastic breast parenchyma, herniation of parenchyma in the areolae, enlarged areolae, superior placement of the inframammary fold, and general asymmetry
• Treatment includes of tuberous breast deformity includes implant placement vi the dual plane technique, radial parenchymal scoring to prevent double bubble and expand the pocket, lowering of the inframammary fold, and circumaerolar mastopexy which helps reduce the size of the areola
• Accessory breast tissue presents as failure of regression of the milk line. Breast tissue remains in locations outside of normal breast along the milk line. 
• Most common location of accessory breast tissue is the axillae. Treatment includes excision after proper work up (mammogram if greater than >40, no palpable masses etc). If young and no abnormalities, do not need workup prior to resection.
• Aberrant breast tissue presents as breast tissue outside of milk line.

Breast Screening: 

• The American Cancer Society recommends optional annual mammograms starting at age 40-44. Those from 45-54 should undergo annual screening mammography. After the age of 55, biennial screening mammography is recommended.
• Breast implant screening mammography includes Elkund views.
• Diagnostic mammograms are obtained if there is a clinical abnormality or abnormal finding on a screening mammography. This generally includes magnification and spot compression.
• Mammographic findings for fat necrosis include: lipid cysts, scattered microcalcifications (round spherical, punctate and diffusely scattered consistent with benign)
• Cluster, branching patterns may be indicative of malignant
• Changes requiring biopsies more common in breast reduction rather than autologous fat grafting.

Implants: The newest generation of implants are more cohesive, have lower rupture rates, and less rippling.

• Smooth implants are associated with more severe capsular contracture and less incidence of BIA-ALCL. 
• Textured implants are associated with less severe contracture and more BIA-ALCL.
• Anatomic implants are shaped anatomically and need a precise surgical pocket as rotation can cause deformity and need for revision. Malposition is a risk with anatomic implants.
• More prone to seroma
• Given that they are also textured they have less capsular contracture
• Higher cross linking improves form stability (cohesive gel). Risks include gel fracture and delamination of the shell.

Placement of breast implants:

• Most important factor for determining prosthesis size is breast base width
• Placement of an implant may be either subglandular, dual plane, or subpectoral.
• Subglandular is placement above the pectoralis muscle but under the breast.
• Dual plane includes placement of the implant subpectorally in the superior pole and subglandular in the inferior pole.
• To determine which is appropriate Tebbets recommends pinching the skin and subcutaneous poles for a “pinch test”. For thickness <2cm, the author recommends dual plane placement of the implant.
• Subpectoral placement is associated with an animation deformity. This is defined as lateral displacement of implants with activation of the pectoralis muscle (weight lifting, pushups etc.)
• Ideal upper pole to lower pole ratio in a female breast is 45:55.

Capsular Contracture:

• Biofilm formation from subclinical infection known cause of capsular contracture.
• Baker grading system: 1) Normal 2) Palpable 3) Visible 4) Painful
• Operative techniques to decrease capsular contracture include an inframmary fold incision, subpectoral implant placement, use of textured implants. Increase risk of capsular contracture include a periareolar approach, subglandular placement, and smooth implants. 
• Site change and implant exchange are the only factors that have consistently been shown to decrease recurrence of capsular contracture.

Evaluation of breast implants: 

• Most recent FDA recommendations include MRI at 5-6 years post-operatively to evaluate for rupture followed by re-evaluation every 2-3 years.
• Findings for rupture include the linguini sign (intracapsular rupture, clinically generally not evident) or tear drop sign.

Complications of breast augmentation: 

• Revision remains the highest risk of breast augmentation.
• Spontaneous galactorrhea is thought to be due to changes in the innervation to chest (interruption of intercostal nerves or pressure related to implant placement).
• Post partum symptomatic galactocele can be treated with bromocriptine which is a dopamine receptor agonist that inhibits milk production.
• Other complications include late seroma which is defined as occurring >1 year after implant placement. This is most commonly related to textured implants and can create a “double capsule” which fills with fluid. Treatment includes capsulectomy and pocket change

Mastopexy improves ptotic breasts. 

Evaluation of breast ptosis: 

• Regnault Ptosis Classification: 
• Grade 1: nipple is at level of IMF (1cm below) 
• Grade 2: nipple is between IMF and lowest contour of breast (1-3cm below)
• Grade 3: nipple is at lowest contour of the breast
• Ptotic breasts are a result of involutional changes after childbirth which are due to decrease in the number of lobules that are replaced by stromal matrix and fat. 

Operative design of mastopexy: 

• Periaerolar: suited for correcting minimal degrees of ptosis (NAC elevation of 1-2cm).
• Complications include flattening of central breast mound, widening of areolar diameter, irregularity, and “bottoming out”
• Areolar spreading most common
• Vertical mastopexies are associated with increased distance from nipple to IMF (length of the vertical pillars).
• Wise pattern mastopexies: Remember that for marking, the angle of divergence of the lower limbs correlates to the amount of tissue removed. Wider angles mean more tissue resection and can create a lower pole deformity.
• This can be forced to be wider by large areolas
• Complications include boxy breast shape
• NAC position is usually set at Pitanguy’s point. This is determined by transposition of inframammary crease onto breast.

Pedicle

• Superior: internal mammary perforators from the second intercostal space
• Central and inferior: internal mammary perforators from the fourth interspace
• Medial pedicle: internal mammary perforators from the third intercostal space
• Lateral pedicle: superficial branches of lateral thoracic artery

Mastopexy with augmentation:

• In general mastopexy with augmentation is more difficult to predict aesthetic results, complications and revision rates are higher, and operative time is longer
• Advantages include improved superior pole projection over mastopexy alone
• Waterfall breast deformity occurs when the ptotic breast hangs off of implant. Treatment includes implant exchange and mastopexy
• Biggest risk of an augmentation mastopexy is need for revision

Complications:

• Superior nipple malposition. Correction includes resection of lower pole if inframammary fold measurement is too long. This is difficult to correct.
• Normal measurements: 
• Sternal notch to nipple: 19-21cm
• IMF to nipple: 7-9cm 

BIA-ALCL: (breast implant associated- ALCL)

• Associated with textured implants (not smooth) and associated macrotexturing.
• Commonly presents as late seroma. First step is to evaluate with an ultrasound followed by an FNA.
• FNA are sent for markers via flow cytometry (CD30+ and ALK negative)
• T cell mediated process
• Treatment include total capsulectomy and explantation, removal of lymphoma.

Miscellaneous:

• Mondor disease. This is a benign self limiting thrombophlebitis of the inframammary veins and is usually diagnosed 2-3 weeks post operatively. Treatment includes warm moist dressings and anti-inflammatory agents.
• Anticoagulation not indicated