A 49-year-old woman presents to her physician with complaints of breast swelling and redness of the skin over her right breast for the past 1 month. She also mentions that the skin above her right breast appears to have thickened. She denies any pain or nipple discharge. The past medical history is significant for a total abdominal hysterectomy at 45 years of age. Her last mammogram 1 year ago was negative for any pathologic changes. On examination, the right breast was diffusely erythematous with gross edema and tenderness and appeared larger than the left breast. The right nipple was retracted and the right breast was warmer than the left breast. No localized mass was palpated. Which of the following statements best describes the patient’s most likely condition?

The inflammation is due to obstruction of dermal lymphatic vessels.

It shows predominant lymphatic spread.

The lesion expresses receptors for estrogen and progesterone.

The lesion is due to Streptococcal infection.

The patient undergoes a mammogram, which shows a 6.5mm sized mass with an irregular border and spiculated margins. A subsequent core needle biopsy of the mass shows infiltrating ductal carcinoma with HER2-positive, estrogen-negative, and progesterone-negative immunohistochemistry staining. Blood counts and liver function tests are normal. Laboratory studies show: Hemoglobin 12.5 g/dL Serum Na+ 140 mEq/L Cl- 103 mEq/L K+ 4.2 mEq/L HCO3- 26 mEq/L Ca2+ 8.9 mg/dL Urea Nitrogen 12 mg/dL Glucose 110 mg/dL Alkaline Phosphatase 25 U/L Alanine aminotransferase (ALT) 15 U/L Aspartate aminotransferase (AST) 13 U/L Which of the following is the most appropriate next step in management?

Breast-conserving therapy and sentinel lymph node biopsy

Bilateral mastectomy with lymph node dissection

A 42-year-old woman presents to the physician because of an abnormal breast biopsy report following suspicious findings on breast imaging. Other than being concerned about her report, she feels well. She has no history of any serious illnesses and takes no medications. She does not smoke. She consumes wine 1–2 times per week with dinner. There is no significant family history of breast or ovarian cancer. Vital signs are within normal limits. Physical examination shows no abnormal findings. The biopsy shows lobular carcinoma in situ (LCIS) in the left breast. Which of the following is the most appropriate next step in management?

Careful observation + routine mammography

Left mastectomy + axillary dissection + local irradiation

Lumpectomy + breast irradiation

A 40-year-old man presents with a painless firm mass in the right breast. Examination shows retraction of the nipple and the skin is fixed to the underlying mass. The axillary nodes are palpable. Which of the following statements is FALSE regarding the above condition?

Lobular cancer is the most common breast cancer in males

BRCA2 mutations are associated with increased risk

These are positive for estrogen receptor

Endocrine therapy plays an important role in treatment

Gynecomastia may be caused by certain medications

A 39-year-old African American woman is admitted to the hospital following a seizure with a severe post-ictal headache. She was diagnosed with breast cancer 1 year ago when she presented with a hard, rock-like, immobile mass with irregular borders accompanied by changes in the breast skin, including erythema and dimpling. She had ipsilateral mobile axillary lymphadenopathy at that time. A biopsy confirmed the diagnosis of stage 2B invasive breast cancer. Her mother died at 42 years of age due to the same type of breast cancer. A CT scan done during this admission reveals multiple metastatic lesions in the brain and liver, along with the involvement of supra- and infra-clavicular lymph nodes. Which of the following molecular profile most likely characterizes this patient?

Progesterone receptor (PR) positive

Estrogen receptor (ER) positive

A 61-year-old woman presents to a surgical oncologist for consideration of surgical removal of biopsy-confirmed breast cancer. The mass is located in the tail of Spence along the superolateral aspect of the left breast extending into the axilla. The surgical oncologist determines that the optimal treatment for this patient involves radical mastectomy including removal of the axillary lymph nodes. The patient undergoes all appropriate preoperative tests and is cleared for surgery. During the operation, multiple enlarged axillary lymph nodes are present along the superolateral chest wall. While exposing the lymph nodes, the surgeon accidentally nicks a nerve. Which of the following physical examination findings will most likely be seen in this patient following the operation?

Scapular protrusion while pressing against a wall

Internal rotation, adduction, and extension of the arm

Weakness in arm flexion at the elbow and numbness over the lateral forearm

Weakness in shoulder abduction and numbness over the lateral shoulder

Weakness in wrist extension and numbness over the dorsal hand

A 47-year-old woman comes to the physician for a mass in her left breast she noticed 2 days ago during breast self-examination. She has hypothyroidism treated with levothyroxine. There is no family history of breast cancer. Examination shows large, moderately ptotic breasts. The mass in her left breast is small (approximately 1 cm x 0.5 cm), firm, mobile, and painless. It is located 4 cm from her nipple-areolar complex at the 7 o'clock position. There are no changes in the skin or nipple, and there is no palpable axillary adenopathy. No masses are palpable in her right breast. A urine pregnancy test is negative. Mammogram showed a soft tissue mass with poorly defined margins. Core needle biopsy confirms a low-grade infiltrating ductal carcinoma. The pathological specimen is positive for estrogen receptors and negative for progesterone and human epidermal growth factor receptor 2 (HER2) receptors. Staging shows no distant metastatic disease. Which of the following is the most appropriate next step in management?

Lumpectomy with sentinel lymph node biopsy, followed by radiation and hormone therapy

Lumpectomy with sentinel lymph node biopsy followed by hormone therapy

Nipple-sparing mastectomy with axillary lymph node dissection followed by hormone therapy

Nipple-sparing mastectomy with axillary lymph node dissection, followed by radiation and hormone therapy

Radical mastectomy followed by hormone therapy

Breast cancer staging and surgical management for USMLE Step 3: High-Yield Surgery Lessons

🗺️ Pathology - Staging the Enemy

TNM Staging (AJCC 8th Ed.) is the cornerstone for prognosis and treatment planning.
T (Tumor Size):
- T1: ≤ 2 cm
- T2: > 2 cm to ≤ 5 cm
- T3: > 5 cm
- T4: Any size with direct extension to chest wall/skin (e.g., ulceration, edema/peau d'orange), or inflammatory breast cancer.
N (Nodal Status):
- Clinically node-negative: Sentinel Lymph Node Biopsy (SLNB) is standard.
- Clinically node-positive: Axillary Lymph Node Dissection (ALND).
⭐ Axillary lymph node status is the single most important prognostic factor in early-stage breast cancer.
M (Metastasis):
- M0: No distant spread.
- M1: Distant spread (bone, lung, liver, brain).

Axillary Lymph Node Levels Diagram

🎀 Breast Cancer Staging & Surgical Management

Staging (TNM):
- T (Tumor): T1 (≤2cm), T2 (>2-5cm), T3 (>5cm), T4 (chest wall/skin, inflammatory).
- N (Nodes): Sentinel Lymph Node Biopsy (SLNB) for clinically node-negative axilla. Axillary Lymph Node Dissection (ALND) for positive SLNB or clinically positive nodes.
- M (Metastasis): M1 indicates distant disease (Stage IV), typically managed non-surgically first.
Surgical Decision-Making:
- Breast Conserving Surgery (BCS): Lumpectomy + SLNB. Requires adjuvant radiation to reduce local recurrence.
- Mastectomy: Removal of breast tissue ± SLNB/ALND. Radiation may still be needed for large tumors or positive nodes.

⭐ For early-stage breast cancer (Stage I/II), BCS followed by radiation therapy offers equivalent survival rates to mastectomy.

Lumpectomy vs. Mastectomy: Pros and Cons

🔪 Axillary Dissection Details

Axillary Anatomy: Nerves and Vessels at Risk in Dissection

Axillary Lymph Node Levels: Defined by relation to pectoralis minor muscle.
- Level I: Lateral to the muscle's lateral border.
- Level II: Posterior/deep to the muscle.
- Level III: Medial to the muscle's medial border.
Nerves at Risk & Deficits:
- Long Thoracic N.: Runs on serratus anterior. Injury → winged scapula (impaired arm abduction >90°).
- Thoracodorsal N.: Travels with thoracodorsal artery. Injury → weak arm adduction, extension, internal rotation.
- Intercostobrachial N.: Sensory nerve. Injury → numbness/paresthesia of medial arm/axilla.

⭐ The intercostobrachial nerve is the most frequently injured nerve during axillary dissection, leading to sensory loss, not motor deficit.

⚠️ Complications - Post-Op Pitfalls

Lymphedema: Chronic, non-pitting edema of the ipsilateral arm. Major risk with Axillary Lymph Node Dissection (ALND); significantly lower with SLNB. Management: compression, physical therapy.
Nerve Injury (during ALND):
- Long Thoracic n.: Serratus anterior palsy → "winged scapula".
- Thoracodorsal n.: Latissimus dorsi weakness → weak arm adduction/internal rotation.
Other: Seroma, hematoma, surgical site infection, chronic pain (post-mastectomy pain syndrome).

⭐ The intercostobrachial nerve is most commonly injured during axillary dissection, causing sensory loss to the medial arm and axilla.

⚡ Biggest Takeaways

TNM staging dictates prognosis; metastasis (M) is the most critical factor.

Sentinel lymph node biopsy (SLNB) is the standard for axillary staging in clinically node-negative patients.

Axillary lymph node dissection (ALND) is reserved for positive SLNB or clinically positive nodes.

Breast-conserving therapy (BCT)-lumpectomy + radiation-offers equivalent survival to mastectomy for early-stage disease.

Mastectomy is indicated for large tumors, multicentric disease, or contraindications to radiation.

Stage IV disease management is primarily systemic therapy, not curative surgery.

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