USMLE STEPS

1)A diabetic patient complains to a physician of a sensation of walking on pebbles with bare feet. Physical examination demonstrates clawing of the toes with flexion of the interphalangeal joints and extension of the metatarsophalangeal joints. Atrophy of which of the following muscles is most likely responsible for the observed changes?

Options:
A. Flexor digitorum longus
B. Lumbricals and interossei
C. Peroneus longus
D. Tibialis anterior
E. Tibialis posterior

2)A leukemia patient who has undergone multiple courses of chemotherapy develops herpes simplex encephalitis. Which of the following would you expect a CT scan of the patient's brain to show?

Options:
A. Generalized volume loss
B. Volume loss selectively in the basal ganglia
C. Volume loss selectively in the brainstem
D. Volume loss selectively in the cerebellum
E. Volume loss selectively in the temporal and frontal lobes

3)A 50-year-old man undergoes biopsy of a reddish scaly plaque on the skin of his thigh. The biopsy is diagnosed as mycosis fungoides. Which of the following was seen on the biopsy?

Options:
A. Keratinocytes with cytoplasmic inclusions
B. Malignant-appearing lymphocytes
C. Nits
D. Septate hyphae
E. Vascular proliferation

4)An 80-year-old woman dies after a long history of progressive memory loss, apraxia, and recurrent episodes of confusion. In the last months of life she was bedridden and unable to recognize familiar faces and objects. The pathologist identifies numerous flame-shaped intracytoplasmic inclusions in neurons of the neocortex and hippocampus. These consist of paired helical filaments (PHFs) on electron microscopy. Which of the following biochemical changes most likely accounts for the development of PHFs in this condition?

Options:
A. Abnormal degradation of amyloid precursor protein (APP)
B. Abnormal phosphorylation of tau
C. Accumulation of advanced glycosylation end (AGE) products
D. Increased expression of APP
E. Precipitation of insoluble alpha-tubulin

5)A family consults a physician because all of the family members are experiencing severe itchiness at night. Examination of the various family members demonstrates large numbers of itchy papules, particularly at the flexor surfaces of the wrists and elbows, buttocks, along the belt line, and genitalia. Careful examination of these areas demonstrates scattered fine wavy lines up to 1 cm in length. A tiny dark dot is visible at one end of many of these lines. Which of the following is the most likely diagnosis?

Options:
A. Cutaneous larva migrans
B. Molluscum contagiosum
C. Pediculosis
D. Rosacea
E. Scabies

6)A patient experiences intermittent, severe pain in the right upper quadrant of the abdomen, especially after fatty meals. Ultrasound demonstrates multiple small opacities in the gall bladder that change with the patient's position. Which of the following is a risk factor for this patient's disorder?

Options:
A. 20 years of age
B. Male sex
C. Native American origin
D. Nulliparity
E. Thin build