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 The right nipple was retracted and the right breast was warmer than the left breast.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 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

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 34-year-old Ethiopian woman who recently moved to the United States presents for evaluation to a surgical outpatient clinic with painful ulceration in her right breast for the last 2 months. She is worried because the ulcer is increasing in size. On further questioning, she says that she also has a discharge from her right nipple. She had her 2nd child 4 months ago and was breastfeeding the baby until the pain started getting worse in the past few weeks, and is now unbearable. According to her health records from Africa, her physician prescribed antimicrobials multiple times with a diagnosis of mastitis, but she did not improve significantly. Her mother and aunt died of breast cancer at 60 and 58 years of age, respectively. On examination, the right breast is enlarged and firm, with thickened skin, diffuse erythema, edema, and an ulcer measuring 3 × 3 cm. White-gray nipple discharge is present. The breast is tender with axillary and cervical adenopathy. Mammography is ordered, which shows a mass with a large area of calcifications, parenchymal distortion, and extensive soft tissue and trabecular thickening in the affected breast. The patient subsequently undergoes core-needle and full-thickness skin punch biospies. The pathology report states a clear dermal lymphatic invasion by tumor cells. Which of the following is the most likely diagnosis?

Ductal carcinoma in situ (DCIS)

Lobular carcinoma in situ (LCIS)

An excisional biopsy is performed and the diagnosis of superficial spreading melanoma is confirmed. The lesion is 1.1 mm thick. Which of the following is the most appropriate next step in management?

Surgical excision with 1-2 cm safety margins and sentinel lymph node study

Surgical excision with 0.5-1 cm safety margins only

Surgical excision with 1 cm safety margins only

Surgical excision with 1-2 cm safety margins only

Surgical excision with 0.5-1 cm safety margins and sentinel lymph node study

A 50-year-old obese woman presents for a follow-up appointment regarding microcalcifications found in her left breast on a recent screening mammogram. The patient denies any recent associated symptoms. The past medical history is significant for polycystic ovarian syndrome (PCOS), for which she takes metformin. Her menarche occurred at age 11, and the patient still has regular menstrual cycles. The family history is significant for breast cancer in her mother at the age of 72. The review of systems is notable for a 6.8 kg (15 lb) weight loss in the past 2 months. The vital signs include: temperature 37.0°C (98.6°F), blood pressure 130/70 mm Hg, pulse 82/min, respiratory rate 17/min, and oxygen saturation 98% on room air. On physical examination, the patient is alert and cooperative. The breast examination reveals no palpable masses, lymphadenopathy, or evidence of skin retraction. A biopsy of the left breast is performed, and histologic examination demonstrates evidence of non-invasive malignancy. Which of the following is the most appropriate definitive treatment for this patient?

Observation with bilateral mammograms every 6 months

Sentinel lymph node biopsy for USMLE Step 2 CK: High-Yield Surgery Lessons

🕵️ Core concept - The Lymph Node Spy

Identifies the first lymph node(s) ("sentinel node") draining a primary tumor, predicting the status of the entire axillary basin.
💡 Purpose: Accurately stages the axilla while minimizing morbidity (e.g., lymphedema, nerve injury) compared to a full Axillary Lymph Node Dissection (ALND).
Technique: Dual-agent injection near the tumor.
- Technetium-99m sulfur colloid (radiotracer)
- Isosulfan blue or Methylene blue (visible dye)

⭐ Per the ACOSOG Z0011 trial, for T1/T2 tumors with 1-2 positive SLNs undergoing breast conservation & whole-breast radiation, ALND may be omitted.

🕵️ Who Needs a Spy?

Primary Indication: Early-stage invasive breast cancer (e.g., T1-T3 tumors) with clinically negative axillary nodes (cN0) on physical exam and imaging.
Special Case: Ductal Carcinoma In Situ (DCIS) when a mastectomy is planned. Mastectomy disrupts lymphatic channels, making future SLNB impossible.
Contraindications:
- Palpable/biopsy-proven axillary nodes (cN+).
- Inflammatory breast cancer.
- Prior axillary surgery or radiation.

⭐ A positive SLNB may lead to complete axillary dissection (ALND) or axillary radiation, especially with minimal nodal burden (1-2 nodes per ACOSOG Z0011).

🗺️ Diagnosis - Mission: Find the Sentinel

Goal: Identify the first lymph node(s) draining the tumor to stage the axilla with minimal morbidity.
Mapping Technique (Dual-agent standard):
- Radiotracer: Technetium-99m ($^{99m}$Tc) sulfur colloid injected pre-op. A gamma probe detects "hot" nodes.
- Blue Dye: Isosulfan or methylene blue injected intra-op for visual identification of "blue" nodes.

⭐ A negative SLNB has a >95% negative predictive value, accurately predicting a disease-free axilla and helping avoid a more morbid axillary lymph node dissection (ALND).

Sentinel Lymph Node Biopsy Procedure

⚠️ Complications - When the Spy Trips

False-Negative Rate: ~5-10%. The most critical limitation.
- Can lead to under-staging and inadequate treatment.
Nerve Injury:
- Intercostobrachial (most common): Upper arm numbness/paresthesia.
- Long thoracic: "Winged scapula" (serratus anterior palsy).
- Thoracodorsal: Weak arm adduction (latissimus dorsi palsy).
Lymphedema: Significantly lower risk than ALND (~5% vs. 20%).
Anaphylaxis: Rare, severe reaction to blue dye (isosulfan).
Site Issues: Seroma, hematoma, infection.

⭐ The false-negative rate is a key limitation, as it can lead to under-staging and sparing a patient from necessary axillary treatment (ALND/radiation).

🕵️ Management - Decoding the Spy's Report

SLNB Negative: Axilla staged N0. No further axillary surgery required.
SLNB Positive: Management depends on the number of positive nodes and planned treatment.

⭐ ACOSOG Z0011 Trial: Revolutionized care by showing that for patients with 1-2 positive SLNs undergoing breast-conserving therapy (BCT) and whole-breast radiation (WBRT), omitting a full axillary lymph node dissection (ALND) does not worsen survival outcomes.

⚡ Biggest Takeaways

Primary goal: Axillary staging for clinically node-negative (cN0) invasive breast cancer.

Avoids morbidity of full axillary lymph node dissection (ALND), especially lymphedema.

Procedure uses a radiotracer and/or blue dye to identify the first draining lymph node(s).

A negative SLN means no further axillary surgery is required.

A positive SLN may lead to completion ALND or axillary radiation.

Contraindicated in patients with clinically positive nodes or inflammatory breast cancer.

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