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 70-year-old man comes to the physician because of right-sided back pain, red urine, and weight loss for the last 4 months. He has smoked one pack of cigarettes daily for 40 years. A CT scan of the abdomen shows a large right-sided renal mass. Biopsy of the mass shows polygonal clear cells filled with lipids. Which of the following features is necessary to determine the tumor grade in this patient?

Nuclear pleomorphism and nucleolar prominence

Invasion of surrounding structures

Involvement of regional lymph nodes

Size of malignant proliferation

A 43-year-old woman presents to your clinic for the evaluation of an abnormal skin lesion on her forearm. The patient is worried because her mother passed away from melanoma. You believe that the lesion warrants biopsy for further evaluation for possible melanoma. Your patient is concerned about her risk for malignant disease. What is the most important prognostic factor of melanoma?

Depth of invasion of atypical cells

Level of irregularity of the borders

A 62-year-old woman presents to her primary care physician for a routine physical exam. The patient has no specific complaints but does comment on some mild weight gain. She reports that she recently retired from her job as a math teacher and has taken up hiking. Despite the increase in activity, she believes her pants have become "tighter." She denies headaches, urinary symptoms, or joint pains. She has a history of hypertension, type 2 diabetes, and rheumatoid arthritis. Her medications include aspirin, lisinopril, rovastatin, metformin, and methotrexate. She takes her medications as prescribed and is up to date with her vaccinations. A colonoscopy two years ago and a routine mammography last year were both normal. The patient’s last menstrual period was 10 years ago. The patient has a father who died of colon cancer at 71 years of age and a mother who has breast cancer. Her temperature is 98.7°F (37°C), blood pressure is 132/86 mmHg, pulse is 86/min, respirations are 14/min and oxygen saturation is 98% on room air. Physical exam is notable for a mildly distended abdomen and a firm and non-mobile right adnexal mass. What is the next step in the management of this patient?

Exploratory laparotomy and debulking

A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

"Can you tell me more about the symptoms you have been experiencing?"

"Does the diarrhea typically precede the constipation, or vice-versa?"

"Is the diarrhea foul-smelling?"

"Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"

"Are the symptoms worse in the morning or at night?"

A 65-year-old man is admitted to the hospital because of a 1-month history of fatigue, intermittent fever, and weakness. Results from a peripheral blood smear taken during his evaluation are indicative of possible acute myeloid leukemia. Bone marrow aspiration and subsequent cytogenetic studies confirm the diagnosis. The physician sets aside an appointed time-slot and arranges a meeting in a quiet office to inform him about the diagnosis and discuss his options. He has been encouraged to bring someone along to the appointment if he wanted. He comes to your office at the appointed time with his daughter. He appears relaxed, with a full range of affect. Which of the following is the most appropriate opening statement in this situation?

What is your understanding of the reasons we did bone marrow aspiration and cytogenetic studies?

Your lab reports show that you have an acute myeloid leukemia

You must be curious and maybe even anxious about the results of your tests.

I may need to refer you to a blood cancer specialist because of your diagnosis. You may need chemotherapy or radiotherapy, which we are not equipped for.

Would you like to know all the details of your diagnosis, or would you prefer I just explain to you what our options are?

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

Surgical margins and R0 resection for USMLE Step 2 CK: High-Yield Surgery Lessons

🔪 Definition & classification - Getting Edgy with Tumors

Surgical Margin: The rim of non-tumor tissue excised around a primary tumor. The goal is complete oncologic removal.
R Classification (Residual Tumor): Describes the status of the margin after resection.
- R0: Complete resection with no microscopic tumor cells at the inked margin (negative margin).
- R1: Microscopic residual tumor at the margin (microscopic positive).
- R2: Macroscopic residual tumor left in the patient (gross positive).

⭐ R0 resection is the single most important prognostic factor for preventing local recurrence and improving overall survival in most solid tumors.

💡 Margin width requirements are tumor-specific:
- Melanoma: 1-2 cm
- Sarcoma: >1 cm
- Breast (DCIS): ≥2 mm

🔬 Microscopy & Pathogenesis - The "No Ink on Tumor" Rule

The primary goal of curative cancer surgery is achieving a negative surgical margin, ensuring no tumor cells are left behind. This is microscopically verified using the "no ink on tumor" principle.

Surgical Margin: The edge or border of the tissue removed in cancer surgery.
Inking: The pathologist coats the outer surface of the resected specimen with ink. This ink marks the true surgical edge that was created by the surgeon.
Microscopic Evaluation: The specimen is sliced, and slides are examined. If tumor cells are found touching the ink, the margin is considered positive.

⭐

Achieving an R0 resection is one of the most critical prognostic factors for long-term survival and cure in most solid malignancies.

Resection Status (R-Status)

Status	Microscopic Finding	Clinical Implication
R0	No tumor at inked margin	Curative Intent; best prognosis
R1	Microscopic tumor at margin	↑ Risk of local recurrence; needs adjuvant therapy/re-excision
R2	Macroscopic residual tumor	Palliative setting; poor prognosis

Margin Assessment Workflow

✂️ Surgical Margins & R0 Resection

Surgical Margin: The rim of normal-appearing tissue removed around a tumor. The goal is achieving "negative" or "clear" margins.
R Classification (Residual Tumor):
- R0: Complete resection; no tumor cells at the margin (microscopically negative). This is the primary goal of curative surgery.
- R1: Microscopic residual tumor at the margin (positive margin).
- R2: Macroscopic (gross) residual tumor left behind.
Prognosis: Margin status is a critical predictor of local recurrence and overall survival. Positive margins (R1/R2) significantly ↑ recurrence risk.

⭐ The required width for a "negative" margin is tumor-specific. For example, >2 mm for breast ductal carcinoma in situ (DCIS), but up to 1-2 cm for high-risk melanoma.

⚡ Biggest Takeaways

R0 resection (negative margins) is the goal of curative surgery and the strongest predictor of local recurrence.

R1 means microscopic residual tumor at the margin, often requiring adjuvant therapy (e.g., radiation).

R2 indicates macroscopic (gross) residual tumor.

A negative margin is confirmed by "no ink on tumor" on pathology.

Required margin width varies by cancer type (e.g., melanoma, sarcoma).

Intraoperative frozen section can assess margins in real-time.

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