QUESTION: 169

A 19-year-old woman begins chemotherapy for an acute leukemia. Although you determine that her renal function is unimpaired prior to the initiation of treatment, you feel that she may be at high risk for development of tumor lysis syndrome given her condition's typically good response to chemotherapy.

Which of the following is an appropriate medication to use as a preventative measure prior to and during her treatment for leukemia?

indomethacin
colchicine
allopurinol
probenecid
sulfinpyrazone

Answer(s): C

Explanation:

Tumor lysis syndrome refers to a series of metabolic disturbances resultant from cancer treatment. It generally occurs when a large number of cancer cells are killed rapidly, releasing the contents of those cells into the systemic circulation. These contents include various ions. Tumor lysis syndrome is typically characterized by a combination of hyperuricemia, hyperkalemia, hyperphosphatemia, hypocalcemia, and lactic acidosis. Besides treatment of electrolyte abnormalities, urine alkalinization and aggressive hydration are frequently included as a part of treatment. Patients with tumor lysis syndrome may also develop oliguric acute renal failure, which arises from the precipitation of uric acid, hypoxanthine, or calcium phosphate within the renal tubules. Acute tubular necrosis is generally not seen in the setting of tumor lysis syndrome. Allopurinol reduces the synthesis of uric acid by blocking the metabolism of xanthine and hypoxanthine to uric acid via xanthine oxidase inhibition. This makes it useful in reducing the risk of hyperuricemia from tumor lysis. Urinary alkalinization and aggressive hydration are also components of treatment. Probenecid and sulfinpyrazone enhance urate excretion by blocking the reabsorption of urate from the proximal tubule. Colchicine is effective in treating acute gout attacks by inhibiting leukocyte migration and phagocytosis. Indomethacin, and other NSAIDs, can be effective in treating acute gout attacks by inhibiting urate crystal phagocytosis. However, low-dose aspirin may actually increase the risk of gout.

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QUESTION: 170

A 19-year-old woman begins chemotherapy for an acute leukemia. Although you determine that her renal function is unimpaired prior to the initiation of treatment, you feel that she may be at high risk for development of tumor lysis syndrome given her condition's typically good response to chemotherapy.

Which of the following is typically seen as a feature of tumor lysis syndrome?

hypokalemia
hypocalcemia
hypophosphatemia
acute necrosis of renal tubules
urine alkalinization

Answer(s): B

Explanation:

Tumor lysis syndrome refers to a series of metabolic disturbances resultant from cancer treatment. It generally occurs when a large number of cancer cells are killed rapidly, releasing the contents of those cells into the systemic circulation. These contents include various ions. Tumor lysis syndrome is typically characterized by a combination of hyperuricemia, hyperkalemia, hyperphosphatemia, hypocalcemia, and lactic acidosis. Besides treatment of electrolyte abnormalities, urine alkalinization and aggressive hydration are frequently included as a part of treatment. Patients with tumor lysis syndrome may also develop oliguric acute renal failure, which arises from the precipitation of uric acid, hypoxanthine, or calcium phosphate within the renal tubules. Acute tubular necrosis is generally not seen in the setting of tumor lysis syndrome. Allopurinol reduces the synthesis of uric acid by blocking the metabolism of xanthine and hypoxanthine to uric acid via xanthine oxidase inhibition. This makes it useful in reducing the risk of hyperuricemia from tumor lysis. Urinary alkalinization and aggressive hydration are also components of treatment. Probenecid and sulfinpyrazone enhance urate excretion by blocking the reabsorption of urate from the proximal tubule. Colchicine is effective in treating acute gout attacks by inhibiting leukocyte migration and phagocytosis. Indomethacin, and other NSAIDs, can be effective in treating acute gout attacks by inhibiting urate crystal phagocytosis. However, low-dose aspirin may actually increase the risk of gout.

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QUESTION: 171

A37-year-old White executive secretary comes to you after she found a lump in her right breast while she was showering. She describes a lesion beneath her right nipple. You question her about her personal and family history. She began menarche at age 12, and she is still having regular menstrual periods. She has had two children; the first was born when she was 25 years old. She has no family history of breast, ovarian, or colon cancer on either her maternal or paternal side. You perform a physical examination including a careful examination of her breasts. You note that her breasts contain many small cysts bilaterally. However, you also palpate a localized, firm, nontender mass below the right areola. You also describe a peau d'orange appearance of the areola. What should you advise her?

She appears to have fibrocystic disease and that she should return for a repeat physical examination in 6 months.
Ask her to make another appointment to see you in 2 months.
Order a mammogram.
Obtain serum markers CA-27/29 and CEA.
Order a breast ultrasound.

Answer(s): C

Explanation:

Any new palpable breast lesion in females (or males) of any age necessitates a mammographic evaluation and biopsy. Delay is inadvisable. Serum tumor markers, such as CA-27/29 (or even less specifically CEA), are useful to follow tumor response to therapy; however tumor markers are not reliable as diagnostic tools in breast cancer because of a relatively low sensitivity. Lobular carcinomas are frequently not visualized on mammogram, particularly standard mammograms; ultrasound however detects these tumors and should be ordered when a palpable lesion is not detected on a mammogram.

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QUESTION: 172

A37-year-old White executive secretary comes to you after she found a lump in her right breast while she was showering. She describes a lesion beneath her right nipple. You question her about her personal and family history. She began menarche at age 12, and she is still having regular menstrual periods. She has had two children; the first was born when she was 25 years old. She has no family history of breast, ovarian, or colon cancer on either her maternal or paternal side. You perform a physical examination including a careful examination of her breasts. You note that her breasts contain many small cysts bilaterally. However, you also palpate a localized, firm, nontender mass below the right areola. You also describe a peau d'orange appearance of the areola.

Amammogram is performed; however, the mammogram demonstrates no abnormality involving either breast. What next should be done?

Tell your patient to feel reassured and return if the mass enlarges.
Tell her to stop drinking caffeine, not to eat chocolate, and to reduce the stress in her life.
Return for another physical examination and mammogram in 6 months.
Order an ultrasound of the right breast and lymph node basin.
Order a CT scan of the breast, chest, and axilla.

Answer(s): D

Explanation:

Any new palpable breast lesion in females (or males) of any age necessitates a mammographic evaluation and biopsy. Delay is inadvisable. Serum tumor markers, such as CA-27/29 (or even less specifically CEA), are useful to follow tumor response to therapy; however tumor markers are not reliable as diagnostic tools in breast cancer because of a relatively low sensitivity. Lobular carcinomas are frequently not visualized on mammogram, particularly standard mammograms; ultrasound however detects these tumors and should be ordered when a palpable lesion is not detected on a mammogram.

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QUESTION: 169

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