A 36-year-old Asian male complains of difficulty swallowing. Esophagoscopy reveals a polypoid mass that is subsequently biopsied. In addition to tumor cells, the esophageal biopsy show normal smooth muscle and striated muscle in the same section. Which portion of the esophagus was the source of this biopsy?
A 26-year-old man presents to his physician with a chronic cough. The man is a smoker, and states that he also gets frequent headaches and aches in his legs when he exercises. Chest x-ray demonstrates notching of his ribs. Which of the following undiagnosed congenital defects may be responsible for these findings?
Administration of an experimental drug that acts on PNS myelin is shown to increase the space constant of an axon in a peripheral nerve. Action potentials traveling down the axon would be predicted to be
A 3-year-old child develops headaches and is brought to the family doctor. Funduscopic examination reveals papilledema; one retina also shows a very vascular tumor. CT of the head demonstrates a cystic tumor of the cerebellum. This child has a high likelihood of later developing which of the following?
A 3-year-old child is referred to a major medical center because of an abdominal mass arising from his right adrenal gland. Biopsy of the lesion demonstrates sheets of small cells with hyperchromatic nuclei containing occasional pseudorosettes composed of circles of tumor cells with central young nerve fibers arising from the tumor cells. Which of the following oncogenes is associated with this patient's tumor?
A child who has had abnormal development of the membranous bones has a broad skull with associated facial and dental anomalies. Which other bones are most likely to also be affected?
A 48-year-old female is being treated for breast carcinoma. Over the past few days, she has been complaining of dysuria and frequency. Laboratory examination revealed the presence of microscopic hematuria. The next day the patient developed gross hematuria. Which of the following agents most likely caused the development of these signs and symptoms?
Which of the following renal structures is most medially located?
An otherwise healthy 3-year-old child is brought to the pediatrician with umbilicated, flesh-colored papules on his trunk. This condition is related to infection with which of the following viruses?
A 30-year-old pregnant woman complains to her physician of feeling very tired during her pregnancy. A complete blood count with differential reveals a hematocrit of 30%, with hypersegmented neutrophils and large, hypochromic red cells. Deficiency of which of the following would be most likely to produce these findings?