A 62-year-old woman presents to her physician with a painless breast mass on her left breast for the past 4 months. She mentions that she noticed the swelling suddenly one day and thought it would resolve by itself. Instead, it has been slowly increasing in size. On physical examination of the breasts, the physician notes a single non-tender, hard, and fixed nodule over left breast. An ultrasonogram of the breast shows a solid mass, and a fine-needle aspiration biopsy confirms the mass to be lobular carcinoma of the breast. When the patient asks about her prognosis, the physician says that the prognosis can be best determined after both grading and staging of the tumor. Based on the current diagnostic information, the physician says that they can only grade, but no stage, the neoplasm. Which of the following facts about the neoplasm is currently available to the physician?

The tumor cells exhibit marked nuclear atypia.

The tumor invades the pectoralis major.

The tumor has spread via blood-borne metastasis.

The tumor has not metastasized to the contralateral superior mediastinal lymph nodes.

The tumor has metastasized to the axillary lymph nodes.

A 59-year-old woman presents to her primary care provider with a 6-month history of progressive left-arm swelling. Two years ago she had a partial mastectomy and axillary lymph node dissection for left breast cancer. She was also treated with radiotherapy at the time. Upon further questioning, she denies fever, pain, or skin changes, but reports difficulty with daily tasks because her hand feels heavy and weak. She is bothered by the appearance of her enlarged extremity and has stopped playing tennis. On physical examination, nonpitting edema of the left arm is noted with hyperkeratosis, papillomatosis, and induration of the skin. Limb elevation, exercise, and static compression bandaging are started. If the patient has no improvement, which of the following will be the best next step?

Vascularized lymph node transfer

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 72-year-old man presents to the physician with blood in his sputum for 3 days. He also mentions that he has had a cough for the last 3 months but thought that it was because of the winter season. He also has often experienced fatigue recently. His temperature is 37.0°C (98.6°F), the respiratory rate is 15/min, the pulse is 67/min, and the blood pressure is 122/98 mm Hg. Auscultation of his chest reveals normal heart sounds but localized rhonchi over the right infrascapular region. A detailed diagnostic evaluation including a complete blood count and other serum biochemistry, chest radiogram, computed tomography of chest and abdomen, magnetic resonance imaging of the brain, bone scan, and pulmonary function tests are ordered, which confirm a diagnosis of limited-disease small cell lung cancer of 2.5 cm (1 in) in diameter, located in the lower lobe of the right lung, with the involvement of ipsilateral hilar lymph nodes and intrapulmonary lymph nodes. The mediastinal, subcarinal, scalene or supraclavicular lymph nodes are not involved, and there is no distant metastasis. There is no additional comorbidity and his performance status is good. The patient does not have any contraindication to any chemotherapeutic agents or radiotherapy. Which of the following is the best treatment option for this patient?

Platinum-based chemotherapy plus etoposide and thoracic radiation therapy

Thoracic radiation therapy followed by prophylactic cranial irradiation

Lobectomy with adjuvant topotecan-based chemotherapy

Pneumonectomy with adjuvant platinum-based chemotherapy and thoracic radiation therapy

Topotecan-based chemotherapy plus thoracic radiation therapy

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

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 39-year-old man presents with painless swelling of the right testis and a sensation of heaviness. The physical examination revealed an intra-testicular solid mass that could not be felt separately from the testis. After a thorough evaluation, he was diagnosed with testicular seminoma. Which of the following group of lymph nodes are most likely involved?

Superficial inguinal lymph nodes (lateral group)

Superficial inguinal lymph nodes (medial group)

Lymph node sampling techniques for USMLE Step 2 CK: High-Yield Surgery Lessons

🎯 Core Principles - The Sentinel Hunt

The Sentinel Lymph Node (SLN) is the first lymph node to receive lymphatic drainage from a primary tumor. Its histological status predicts the status of the entire regional nodal basin, guiding decisions on further axillary lymph node dissection (ALND).

Lymphatic Mapping Techniques:
- Blue Dye: Isosulfan blue (or methylene blue) is injected peritumorally. It stains lymphatic channels and the SLN blue for direct visual identification. ⚠️ Risk of anaphylaxis with isosulfan.
- Radiotracer: Technetium-99m ($^{99m}$Tc) sulfur colloid is injected, localizing in the SLN. Detected intraoperatively with a handheld gamma probe.

Sentinel lymph node biopsy with dye injection and removal

⭐ The dual-tracer technique (blue dye + radiocolloid) is the gold standard, maximizing the SLN identification rate to >95% in melanoma and breast cancer.

🔪 Management: Biopsy vs. Dissection

Decision-making for regional lymph nodes hinges on clinical status. The goal is accurate staging with minimal morbidity.

Feature	Sentinel Lymph Node Biopsy (SLNB)	Axillary/Regional Lymph Node Dissection (ALND/RLND)
Indication	Clinically node-negative (cN0) disease	Clinically node-positive (cN+) or SLNB-positive disease
Goal	Staging (diagnostic)	Therapeutic & Staging (locoregional control)
Extent	Removal of 1-3 "sentinel" nodes	Removal of a larger group of nodes (e.g., Level I/II axillary)
Morbidity	Low	High
Complications	↓ Lymphedema, ↓ nerve injury	↑ Lymphedema (~20-30%), ↑ nerve injury, shoulder dysfunction

⭐ ACOSOG Z0011 Trial: In early-stage breast cancer (T1/T2, cN0) with 1-2 positive sentinel nodes undergoing lumpectomy and whole-breast radiation, ALND shows no survival benefit over SLNB alone.

⚠️ Complications - Post-Op Perils

Lymphedema: Chronic, non-pitting edema in the ipsilateral arm from impaired lymphatic drainage.

⭐ Lymphedema risk is significantly lower with Sentinel Lymph Node Biopsy (SLNB) (~~5%) compared to Axillary Lymph Node Dissection (ALND) (~~20-30%).
Nerve Injury:
- Long Thoracic n.: Innervates serratus anterior → Injury causes "Winged Scapula".
- Thoracodorsal n.: Innervates latissimus dorsi → Injury causes weak arm adduction & internal rotation.
- Intercostobrachial n.: Sensory nerve → Injury causes numbness of medial arm/axilla.
Seroma: Fluid collection in surgical dead space; may require aspiration.
Shoulder Dysfunction: Pain, stiffness, ↓ range of motion.

Winged Scapula: Anatomy and Physical Exam Finding

📊 Clinical Correlations - Staging Significance

TNM Staging: Lymph node status is the 'N' in TNM staging ($N_x, N_0, N_1-N_3$), a powerful independent prognostic factor for most solid tumors.
Prognosis: Node positivity (N+) significantly worsens prognosis and increases the risk of distant recurrence.
Adjuvant Therapy: A positive node finding is a primary driver for recommending adjuvant systemic chemotherapy and/or regional radiation therapy (XRT).
Decision Impact: The number and anatomic level of positive nodes determine the specific N-stage, guiding treatment intensity.

⭐ For many cancers (e.g., breast, colon), the absolute number of positive lymph nodes is a more powerful predictor of survival than the size of the primary tumor (T-stage).

⚡ Biggest Takeaways

Sentinel Lymph Node Biopsy (SLNB) is the standard for staging clinically node-negative breast cancer and melanoma.

It identifies the first draining lymph node(s) using a radiotracer (technetium-99m) and/or blue dye.

A negative SLNB avoids a more morbid Axillary Lymph Node Dissection (ALND).

ALND is indicated for positive SLNB or clinically palpable, biopsy-proven nodes.

Major ALND risk is chronic lymphedema; also nerve injury (long thoracic, thoracodorsal).

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