A 66-year-old woman comes to the office due to 2 months of worsening fatigue and dyspnea with moderate exertion.  The patient has a history of breast cancer treated with surgery and combination chemotherapy 6 years ago.  She has no other medical conditions.  Vital signs are within normal limits.  Physical examination reveals normal jugular venous pressure, clear lungs, and normal heart sounds; there is no hepatosplenomegaly, lymphadenopathy, or extremity edema.  Laboratory results are as follows:

Peripheral blood smear shows oval macrocytic red cells and hyposegmented neutrophils.  Bone marrow biopsy of this patient is most likely to reveal which of the following?

A previously healthy 30-year-old woman is admitted to the hospital.  She complains of a rash over her ankles that started 2 weeks ago and slowly spread up to her knees.  The patient has no other medical problems and takes no regular medications.  Her vital signs are within normal limits.  Physical examination shows fine petechiae and purpura around her ankles and lower legs.  There is no lymphadenopathy or hepatosplenomegaly.  Laboratory results are as follows:

Peripheral blood smear shows thrombocytopenia.  After reviewing the laboratory results, the admitting resident orders 6 units of random donor platelet transfusion.  The following day, the platelet count is 10,000/µL.

Item 1 of 2

Which of the following is the most likely cause of the drop in the platelet count?

Item 2 of 2

Which of the following is the most appropriate next step in management of this patient?

A 66-year-old man comes to the office due to several weeks of back and lower extremity pain.  The pain feels dull and achy and is worsened by movement, causing him to have difficulty bearing weight and ambulating.  He has had no bladder or bowel dysfunction, extremity weakness, or numbness.  The patient takes metformin for type 2 diabetes mellitus.  He drinks 2 alcoholic beverages daily.  Physical examination shows no gross abnormality or deformity of the back or extremities.  There is no swelling or redness of the legs, and neurological examination is normal.  A radiograph of the right lower extremity is shown in the exhibit.  Laboratory results are as follows:

Which of the following is the most likely explanation for this patient’s bone changes?

A 54-year old Caucasian man comes to the office complaining of fatigue, poor exercise tolerance, and an unexplained weight loss over the last 6 months.  He does not use tobacco, alcohol, or drugs.  His family history is noncontributory.  He takes no medications.  His vital signs are within normal limits.  Examination reveals mild splenomegaly but no lymphadenopathy.  Laboratory tests show the following:

Cytogenetic testing reveals a bcr/abl translocation.  Which of the following is the best initial treatment option for this patient?

A 64-year-old man with diffuse large B-cell lymphoma is hospitalized for chemotherapy initiation.  The patient has extensive bulky lymphadenopathy.  Medical history also includes hypertension and stage 3 chronic kidney disease.  Treatment with cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab is begun.  The patient is also given intravenous hydration and rasburicase.  Four days later, his serum creatinine is acutely elevated and his urine output is decreased.  Vital signs are normal.  Cardiopulmonary examination is normal.  The abdomen is soft with no distension or tenderness.  Laboratory studies are as follows:

Urinalysis shows no cells or casts.  Which of the following is the most likely cause of this patient’s acute kidney injury?

A 62-year-old Caucasian man comes to the office with complaints of a dull, non-throbbing headache, hearing loss on the left side, and persistent tinnitus.  His symptoms have been getting progressively worse for the last two weeks.  He has a history of small cell cancer of the lung, which was treated with a combination of chemotherapy and radiotherapy four months ago.  His lung mass has reduced considerably in size after its treatment.  A contrast-enhanced magnetic resonance imaging scan shows a 1 x 2 cm circumscribed mass in the left cerebellopontine angle compressing the eighth cranial nerve.  There is another small 0.5 x 1 cm mass in the left frontal lobe cortex with significant edema surrounding the lesion.  Which of the following is the most likely cause of this patient’s symptoms?

A 35-year-old woman comes to the office for evaluation of fatigue and exertional dyspnea.  She has a history of systemic lupus erythematosus and is noncompliant with therapy.  The patient takes naproxen as needed for joint pains.  Vital signs are within normal limits.  Examination shows mild pallor.  The remainder of the examination shows no abnormalities.  Laboratory results are as follows:

Which of the following is the most likely underlying cause of her current condition?

A 29-year-old woman with chronic anemia comes to the emergency department with fatigue and progressive dyspnea.  Physical examination shows pallor but no jaundice.  Lungs are clear on auscultation and abdominal examination is benign.  Laboratory results are as follows:

Packed red blood cell transfusion is started.  Thirty minutes later, the patient complains of severe bilateral flank pain.  She has received multiple blood transfusions in the past, but all were uncomplicated.  Her temperature is 38.3 C (101 F), blood pressure is 100/70 mm Hg, pulse is 120/min, and respirations are 16/min.  Pulse oximetry is 97% on room air.  Urine is dark.  Which of the following is the best next step in management of this patient?

A 55-year-old woman is being evaluated for persistent nonproductive cough.  She also has had worsening exercise intolerance and fatigue for the past 4 weeks.  Physical examination shows conjunctival pallor.  Laboratory results are as follows:

Serum chemistry and kidney function test results are normal.  Iron studies and serum vitamin B₁₂ and folic acid levels are within normal limits.  Chest imaging reveals an anterior mediastinal mass.  Which of the following is the most likely cause of this patient’s hematologic disorder?

A 54-year-old woman with stage 4 chronic kidney disease due to polycystic kidney disease undergoes elective arteriovenous fistula creation.  Excessive bleeding is noted during the surgery, and postoperatively, the patient experiences prolonged oozing that is persistent despite the application of pressure.  The patient says she has had recent episodes of easy bruising and epistaxis but recalls no excessive bleeding after cesarean delivery 20 years ago.  Medical history also includes hypertension.  Vital signs are within normal limits.  Preoperative laboratory results are as follows:

Which of the following is the best next step in management of this patient’s bleeding?

A 48-year-old woman complains of persistent fatigue and daytime sleepiness.  Her other medical problems include hypertension and rheumatoid arthritis.  Her medications include naproxen, enalapril, and a multivitamin supplement with iron.  She has no known drug allergies.  Vital signs are within normal limits.  Examination shows conjunctival pallor and bilateral hand joint deformities with tenderness to palpation at metacarpophalangeal joints.  Stool testing for occult blood is negative.

Laboratory results are as follows:

Which of the following would be the most appropriate next step in managing this patient’s anemia?

A 56-year-old previously healthy man comes to the office with a 1-week history of worsening pain, paresthesia, and blackish discoloration of several fingers.  He also has been experiencing fatigue and back pain over the past 2 months.  He does not use tobacco, alcohol, or recreational drugs.  Temperature is 37.2 C (99 F), blood pressure is 130/80 mm Hg, and pulse is 86/min and regular.  The patient’s hand is shown in the image below:

There are areas of vertebral tenderness on palpation of the spine, and skin examination shows livedo reticularis and a retiform, purpuric lower extremity rash.  Laboratory evaluation shows normocytic anemia and elevated levels of serum creatinine, serum calcium, and erythrocyte sedimentation rate.  Serum total protein is elevated with reversal of the albumin/globulin ratio.  Radiographs reveal scattered lytic vertebral lesions.  Which of the following is most likely involved in the pathogenesis of this patient’s hand findings?