Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.
A 69-year-old woman is evaluated for a lump under her arm found on self-examination. She is otherwise healthy and has no other symptoms. Medical and family histories are unremarkable, and she takes no medications.
On physical examination, temperature is 37.4 °C (99.3 °F), blood pressure is 110/70 mm Hg, pulse rate is 72/min, and respiration rate is 14/min. The patient has a hard, fixed, 2-cm mass palpable in the right axilla. The remainder of the examination, including breast examination, is normal.
Complete blood count and serum creatinine, total bilirubin, and alkaline phosphatase levels are normal.
A needle aspirate of the right axillary mass reveals adenocarcinoma. Bilateral mammography and breast MRI are normal. CT scan of the chest, abdomen, and pelvis demonstrates the enlarged axillary lymph node and no other abnormalities.
Which of the following is the most appropriate initial treatment?
A: Breast cancer chemotherapy regimen
B: Excision of the axillary lymph node
C: Mastectomy with axillary lymph dissection
D: Radiation therapy to the right axilla
MKSAP Answer and Critique
The correct answer is C: Mastectomy with axillary lymph dissection.
Mastectomy and axillary lymph dissection should be performed, and the patient should be treated for breast cancer. A patient is considered to have cancer of unknown primary (CUP) site when a tumor is detected at one or more metastatic sites and routine evaluation fails to define a primary site. The initial workup of patients presenting with presumed CUP should not be exhaustive but should focus on evaluation of likely primary sites. Women who present with axillary lymphadenopathy without other findings should be treated for stage II breast cancer. An occult primary tumor is identified on mastectomy in 50% to 60% of these patients, even when the physical examination and mammogram are normal. MRI of the breast can often identify a primary site even if mammography is normal and can often lead to breast conservation and is a recommended part of the evaluation. Patients who have CUP with axillary lymphadenopathy only and who are found to have breast cancer have the same survival rate as patients with stage II disease.
This patient has potentially curable disease, and neither chemotherapy alone nor radiation therapy alone, which is palliative, is adequate. Excision of the lymph node alone would also be insufficient because the breast is the presumed source of the primary tumor, and there may be tumor involvement in additional lymph nodes.
Key Point
- Cancer of unknown primary site presenting as axillary lymphadenopathy in women should be managed as stage II breast cancer.
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