Usmle practice Q.1
A 59-year-old man has experienced chronic fatigue for the past 18 months. On physical examination he is afebrile. A chest radiograph shows bilateral pulmonary edema and a prominent border on the left side of the heart. The representative gross appearance of the heart is shown. Laboratory studies show:
Serum glucose - 74 mg/dL
Total cholesterol - 189 mg/dL
Total protein - 7.1 g/dL
Albumin - 5.2 g/dL
Creatinine - 6.1 mg/dL
Urea nitrogen - 58mg/dL
What is the most likely diagnosis?
A) Chronic alcoholism
B) Systemic hypertension
C) Pneumoconiosis
D) Hemochromatosis
E) Diabetes mellitus
Answer & Explanation :
The correct answer is B.
The markedly thickened left ventriclular wall is characteristic of hypertrophy owing to increased pressure load from hypertension, which often is associated with chronic renal disease.
Chronic alcoholism is associated with dilated cardiomyopathy.
Pneumoconiosis produce restrictive lung disease with cor pulmonale and predominantly right ventricular hypertrophy.
Hemochromatosis leads to restrictive cardiomyopathy.
Diabetes mellitus accelerates atherosclerosis, leading to ischemic heart disease and myocardial infarction.
USMLE Practice question #2
A child is in the nursery one day after birth. A nurse notices a urine-like discharge being expressed through the umbilical stump.
What two structures in the embryo are connected by the structure that failed to obliterate during the embryologic development of this child?
A) Pulmonary artery - aorta
B) Bladder - yolk sac
C) Bladder - small bowel
D) Liver - umbilical vein
E) Kidney - large bowel
Explanation: CORRECT ANS. IS B
Leaking of urine from the umbilical stump represents a failure of obliteration of the urachus. The urachus is the embryological remnant of the allantois that originally connected the bladder to the yolk sac.
Failure of urachal obliteration results in an abnormal connection between the bladder and outside. In severe cases, the bladder can extrude through the umbilicus (urachal diverticulum) and must be corrected surgically. During normal development the allantois provides a connection between the bladder and yolk sac.
It then gives rise to the umbilical artery and vein. During normal development the urachus is obliterated and gives rise to the the median umbilical ligament which connects the bladder to the anterior abdominal wall.
Lipskar et al. review their experience with the non-operative management of urachal remnants. They found that in many cases, drainage of a urachal cyst will precipitate obliteration of the cyst over time. They found that this process would occur even in cysts that showed signs of infection. So, the correct answer is B.
USMLE Practice question #3
A 5-year-old girl is brought to her pediatrician because her mother says she is frequently bumping into stationary objects while playing. Visual field examination shows bilateral peripheral vision defects. CT of the head reveals calcifications in the pituitary fossa. Which of the following is the most likely origin of this child's brain tumor?
A) Adenohypophyseal lactotrophs
B) Fourth ventricle neuroectoderm
C) Rathke's pouch
D) Vascular endothelium
E) Ventricular lining
Explanation:
The visual field defect described is a bitemporal hemianopia, typically caused by lesions in the sella turcica impinging on the optic chiasm. In children the most common tumor in this location is a craniopharyngioma, derived from the remnants of Rathke's pouch. This embryologic structure buds from the roof of the mouth to form the anterior pituitary. Bitemporal hemianopia is typically accompanied by severe headaches and poor pituitary function. Treatment includes surgery, radiotherapy, or both. 📝The correct answer is C.
USMLE Practice question #4
A baby boy dies 2 days after birth. He was born with wrinkled skin, deformed limbs, and abnormal facies. The mother's pregnancy was complicated by oligohydramnios.
Which of the following embryologic process most likely failed in this child?
A) Development of dermis
B) Development of the kidneys
C) Fusion of maxillary and medial nasal prominences
D) Migration of neural crest cells to the distal colon
E) Outgrowth of limb buds
Source: First Aid. Embryology
Explanation
The correct answer is B. The presentation described here is consistent with Potter's syndrome, or bilateral renal agenesis. The failure of both kidneys to develop leads to oligohydramnios because the fetus cannot excrete urine into the amniotic sac. This in turn allows compression of the fetus by the uterine wall, leading to limb deformities, abnormal facies, and wrinkly skin. Death occurs shortly after birth unless an appropriate donor is found.
Answer A is incorrect. A failure of development of the dermis would not present with oligohydramnios or deformed limbs, but rather skin abnormalities.
Usmle Practice question #5
A neonate is found to have strong, bounding pulses in both upper extremities and carotids, but her femoral pulses are very weak. She is diagnosed with coarctation of the aorta and is taken to surgery to correct the defect. Subsequent follow-up examinations show no further heart abnormalities. Sixteen years later, the patiet is noted to have poorly developed sexondary sexual characteristics, including persistent, nonprogressive Tanner stage 2 breast and pubic hair development.
She has not experienced menarche. Which of the following would most likely be found in this patient?
A) Decreased estrogen levels
B) Normal ovaries
C) Patent ductus arteriosus
D) Simian crease
E) 46, XY karyotype
#embryology
Source: First Aid. Embryology
Explanation: The patient has Turner's syndrome, which is associated with coarctation of the aorta. Turner's syndrome often presents in adolescence with amenorrhea, and a diagnostic work-up shows a 45, XO karyotype. Patients with Turner's syndrome have poor development of secondary sexual characteristics and are infertile. So the correct answer is A.
Those patients have rudimentary ovaries and that is why the answer B is incorrect.
Answer C is incorrect, because Turner's syndrome is not associated with PDA. Also, in the vignette the patient's cardiac examination is normal. With a PDA, the patient would have a continuous machinelike murmur.
Answer D is incorrect, because a simian crease is seen in Down's syndrome (trisomy 21), but not in Turner's syndrome.
Answer E is incorrect, because patients with Turner's syndrome have a 45, XO karyotype.
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