QUESTION: 197

A64-year-old man with a long history of smoking but no significant past medical history presents to his physician's office complaining of a 12 week history of worsening dyspnea, facial swelling, and discoloration. He has also had swelling and discomfort of his right arm. Physical examination reveals edema with plethora of the face and right arm, with prominent collateral veins over the chest wall.

What test is most likely to establish the cause of the patient's symptoms?

PA and lateral chest radiograph
echocardiogram
CT of the chest with intravenous contrast
ultrasound with Doppler flow studies of the right arm
arteriogram of the carotid and axillary arteries

Answer(s): C

Explanation:

The patient's most likely diagnosis is superior vena cava syndrome (SVCS), which is usually due to external compression of the SVC by tumor or lymph nodes, sometimes associated with intraluminal thrombosis. The diagnosis is established by CT of the chest with intravenous contrast, which can demonstrate the level and extent of obstruction, as well as the presence of any caval thrombus. Plain chest radiography may show some mediastinal widening, but yields much less information. Echocardiography would be appropriate if the patient had suspected pericardial effusion with tamponade, but that would not produce unilateral arm edema and discoloration. Doppler studies of the deep veins of the arm would be useful if the problem were isolated to the upper extremity. In this case, the cerebral venous drainage is also involved, so the obstruction is more proximal, i.e. at the level of the SVC. Arteriogram would not be indicated, since the issue in this case is venous obstruction, not arterial insufficiency. Unless the patient has cerebral edema with mental status changes or upper airway compromise due to tracheal obstruction, the diagnosis of SVCS is not immediately life-threatening, and emergent therapy is not usually indicated. The majority of patients with SVCS present with this as the initial presentation of their malignancy, before a tissue diagnosis has been established. This is problematic, since therapy is guided by the underlying malignancy (radiation therapy for non-small cell lung cancers, chemotherapy +/- radiation for small cell lung cancers or lymphomas), but empiric initiation of radiation or glucorticoids (if the underlying diagnosis is lymphoma) may obscure the histologic diagnosis. The most important initial step is to try to obtain a biopsy to establish the cancer type before initiating therapy. If symptoms are severe, placement of intravascular stents may provide rapid symptomatic relief without compromising subsequent diagnostic or therapeutic efforts. Surgical intervention is rarely indicated, and usually only for benign causes of SVCS.

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QUESTION: 198

A64-year-old man with a long history of smoking but no significant past medical history presents to his physician's office complaining of a 12 week history of worsening dyspnea, facial swelling, and discoloration. He has also had swelling and discomfort of his right arm. Physical examination reveals edema with plethora of the face and right arm, with prominent collateral veins over the chest wall.

Following the establishment of a diagnosis, what is the most appropriate initial therapy?

elevation of the head and monitoring for airway obstruction
urgent radiation therapy
administration of glucocorticoids
empiric chemotherapy for suspected lung cancer
surgical evaluation for resection of the obstructing mass

Answer(s): A

Explanation:

The patient's most likely diagnosis is superior vena cava syndrome (SVCS), which is usually due to external compression of the SVC by tumor or lymph nodes, sometimes associated with intraluminal thrombosis. The diagnosis is established by CT of the chest with intravenous contrast, which can demonstrate the level and extent of obstruction, as well as the presence of any caval thrombus. Plain chest radiography may show some mediastinal widening, but yields much less information. Echocardiography would be appropriate if the patient had suspected pericardial effusion with tamponade, but that would not produce unilateral arm edema and discoloration. Doppler studies of the deep veins of the arm would be useful if the problem were isolated to the upper extremity. In this case, the cerebral venous drainage is also involved, so the obstruction is more proximal, i.e. at the level of the SVC. Arteriogram would not be indicated, since the issue in this case is venous obstruction, not arterial insufficiency. Unless the patient has cerebral edema with mental status changes or upper airway compromise due to tracheal obstruction, the diagnosis of SVCS is not immediately life-threatening, and emergent therapy is not usually indicated. The majority of patients with SVCS present with this as the initial presentation of their malignancy, before a tissue diagnosis has been established. This is problematic, since therapy is guided by the underlying malignancy (radiation therapy for non-small cell lung cancers, chemotherapy +/- radiation for small cell lung cancers or lymphomas), but empiric initiation of radiation or glucorticoids (if the underlying diagnosis is lymphoma) may obscure the histologic diagnosis. The most important initial step is to try to obtain a biopsy to establish the cancer type before initiating therapy. If symptoms are severe, placement of intravascular stents may provide rapid symptomatic relief without compromising subsequent diagnostic or therapeutic efforts. Surgical intervention is rarely indicated, and usually only for benign causes of SVCS.

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QUESTION: 199

A 25-year-old woman with acute myelocytic leukemia is undergoing induction chemotherapy and presents to the Emergency Center complaining of a 1-day history of fever to 102º F with no other symptoms. Other than having a fever, her vital signs and physical examination are normal. Laboratory evaluation reveals pancytopenia, with a WBC count of 0.3 k/L, hemoglobin concentration of 9.2 mg/dL, and platelet count of 23,000/L.
What is the most appropriate initial management?

Obtain blood cultures, urine culture, a chest x-ray, and discharge patient to home with follow-up in 12 days to review culture results.
Obtain blood cultures, urine culture, a chest x-ray, and admit the patient to the hospital for observation with plan to institute antibiotics if any culture becomes positive.
Obtain blood culture, urine culture, a chest x-ray, and admit the patient to the hospital for empiric broad- spectrum antibiotics with Gram-negative coverage.
Obtain blood culture, urine culture, a chest x-ray, and admit the patient to the hospital for empiric antibiotics with Gram-positive coverage.
Forego cultures and admit the patient to the hospital for empiric antibiotics with both Gram-positive and Gram-negative coverage.

Answer(s): C

Explanation:

This patient has neutropenia (neutrophil count <500/L) with fever. For high-risk patients, such as patients with leukemia, the standard of care is to obtain cultures and a chest radiograph, perform any other studies as indicated by the patient's clinical presentation, and initiate empiric antibiotic therapy. Guidelines from the Infectious Disease Society of America recommend empiric broad-spectrum coverage for Gram-negative organisms, including anti-pseudomonal coverage. Antibiotics such as vancomycin, for Gram-positive infection, are added if there is hypotension, suspicion for a central venous catheter-related infection, or recent or current evidence for Gram-positive infection (such as MRSA colonization, or positive culture for Gram-positive cocci).

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QUESTION: 200

A 32-year-old man who is HIV-positive was found to have Burkitt's lymphoma with diffuse bulky abdominal disease. He now reports to the hospital and is scheduled to begin chemotherapy. Admission laboratory studies show elevations of his uric acid at 15 mg/dL, serum phosphorus at 8.5 mg/dL, creatinine at 2.9 mg/ dL, and potassium at 6.1 mEq/L.

What therapy is most likely to reverse the patient's metabolic abnormalities?

administration of intravenous saline with mannitol to try to keep urine output >2.5 L/day
allopurinol 300 mg/day
administration of intravenous sodium bicarbonate to keep urinary pH >7.0
hemodialysis
administration of the recombinant uricase enzyme rasburicase to lower uric acid levels

Answer(s): D

Explanation:

This patient has tumor lysis syndrome (TLS), a group of metabolic derangements due to rapid cell turnover with release of intracellular contents, such as phosphate and potassium, and increased purine metabolism, leading to hyperuricemia. It is usually seen after the initiation of cytotoxic chemotherapy, but occasionally occurs spontaneously in patients with bulky disease such as Burkitt's lymphoma. The uric acid crystallizes in the renal tubules and can cause oliguric renal failure. Once renal failure has occurred, patients usually require hemodialysis until renal function recovers. Each of the other choices may be employed to prevent the development of TLS in high-risk patients prior to beginning chemotherapy

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QUESTION: 197

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QUESTION: 199

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