USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 561:

  A39-year-old woman known to have fibrocystic disease of the breast complains of persistent fullness and pain in both breasts. Which of the following drugs will be most effective in relieving her symptoms?

  A. tamoxifen

  B. bromocriptine

  C. medroxyprogesterone acetate

  D. danazol

  E. hydrochlorothiazide

  Correct Answer: D

  Danazol, in oral doses of 100, 200, or 400 mg daily for 46 months, relieves breast pain and reduces nodularity in 90% of women. The beneficial effects often last for several months after discontinuation of the drug. Tamoxifen is a synthetic antiestrogen that competes with estrogen receptors in the breast. Relief of symptoms symptoms has been achieved in approximately 70% of women in small studies, and seems to be ore effective in women with cyclic rather than continuous pain. Bromocriptine inhibits prolactin secretion, not recognized as a cause of fibrocystic breast disease and mastodynia. Oral progestins (e.g., medroxyprogesterone acetate), depot medroxyprogesterone acetate (Depo Provera), or OCs may provide symptomatic relief, but symptoms usually return after these are stopped. Hydrochlorothiazide provides unpredictable relief of symptoms.

• Question 562:

  A 55-year-old woman has a bloody discharge from her left breast. A mammogram discloses a cluster of

  microcalcifications 3 cm beneath her left nipple.

  Which of the following is the best predictor of survival after appropriate treatment of breast cancer?

  A. an initial tumor 1.5 cm or smaller in diameter

  B. the presence of estrogen receptors

  C. the presence of progesterone receptors

  D. a well-differentiated tumor

  E. axillary nodes negative for cancer

  Correct Answer: A

  In women with a primary tumor of 11.5 cm or less, the recurrence risk is approximately 15%, primarily because the likelihood of complete excision is greatest. Women with positive sex- steroid receptors in the tumor also have a better prognosis for several reasons: the tumor tends to be better differentiated, and 5year therapy with tamoxifen significantly reduces recurrence. Although survival decreases as the number of positive axillary lymph nodes increases, the role of sentinel lymph node biopsy and axillary lymphadenectomy has become controversial. There appears to be a trend against axillary lymphadenectomy, especially with ductal carcinoma in situ less than 1.5 cm diameter.

• Question 563:

  A 55-year-old woman has a bloody discharge from her left breast. A mammogram discloses a cluster of microcalcifications 3 cm beneath her left nipple.

  Which of the following is the most common type of breast cancer?

  A. inflammatory carcinoma

  B. lobular carcinoma in situ

  C. lobular infiltrating carcinoma

  D. infiltrating ductal carcinoma

  E. ductal carcinoma in situ

  Correct Answer: D

  Infiltrating (invasive) ductal carcinoma accounts for 6580% of all breast carcinomas. Infiltrating lobular carcinoma accounts for 1014%, and the others 5% or less

• Question 564:

  A 55-year-old woman has a bloody discharge from her left breast. A mammogram discloses a cluster of microcalcifications 3 cm beneath her left nipple.

  Which of the following factors is associated with the greatest lifetime risk for developing breast cancer?

  A. obesity

  B. early menarche

  C. late menopause

  D. age

  E. having a mother with a history of breast cancer

  Correct Answer: D

  The factor associated with the greatest lifetime risk for developing breast cancer is age of the woman. Hereditary breast cancers account for 510% of all breast cancers and give the woman a relative risk of approximately 2. The relative risk is 4 with two first-degree relatives. Increased lifetime estrogen exposure is a minor risk factor for breast cancer. Obesity, early menarche, late menopause, and low parity are associated with an increased lifetime estrogen exposure and are minor risk factors for breast cancer. The prevalence of breast cancer increased from 30 per 10,000 women years (no hormone replacement) to 38 per 10,000 women years (women on hormone replacement), according to data from the Women's Health Initiative. This increase was not statistically significant, but the hormone arms of the study were stopped after 5.56 years because a prestudy threshold defined by the investigators' Data Safety Monitoring Board was exceeded. Stated otherwise, the risk of breast cancer increases from 3.3 to 4.1 per 1000 women using hormone replacement. Estrogens are considered promoters of breast cancer rather than inducers or initiators.

• Question 565:

  A 55-year-old woman has a bloody discharge from her left breast. A mammogram discloses a cluster of microcalcifications 3 cm beneath her left nipple.

  Which of the following is the best next step in her evaluation?

  A. cytologic evaluation of the nipple discharge

  B. fine-needle aspiration under radiologic guidance

  C. MRI of the breast and axillary nodes

  D. image-guided percutaneous biopsy of the left breast

  E. segmental mastectomy

  Correct Answer: D

  Both the bloody nipple discharge and the microcalcifications are indications for a breast biopsy. Although there are benign-appearing radiographic calcifications, clusters of calcification are associated with a 25% chance of a cancer. An image-guided percutaneous biopsy is preferred because a fine- needle biopsy has about a 20% false negative rate. Cytology is a screening tool. In the presence of significant risk factors for cancer, a tissue diagnosis is mandatory. Imaging studies are also screening tools with a false negative and a false positive rate, making such studies inappropriate fordiagnosis

• Question 566:

  A 55-year-old woman has a bloody discharge from her left breast. A mammogram discloses a cluster of microcalcifications 3 cm beneath her left nipple.

  Which of the following is the principal advantage of a fine-needle aspiration of a breast mass?

  A. It reassures the patient if it is negative.

  B. It reduces the number of open breast biopsies.

  C. It differentiates between noninvasive and invasive cancer.

  D. It replaces the need for subsequent mammography.

  E. It helps to determine the extent of in situ breast carcinoma.

  Correct Answer: B

  The advantages of a fine-needle aspiration of a breast mass are that it can distinguish between a cystic and solid lesion, and it reduces the number of open breast biopsies when it is positive for cancer. However, a negative needle biopsy is nondiagnostic (and nonreassuring), and an open biopsy is still necessary. A fineneedle biopsy does not differentiate between noninvasive and invasive cancer, nor does it delineate the extent of in situ disease. Most breast surgeons will not perform definitive surgery (e.g., mastectomy or lumpectomy with lymph node dissection) without histologic confirmation of cancer: core-needle biopsy, surgical biopsy, or frozen section at the time of lumpectomy or mastectomy

• Question 567:

  A 34-year-old woman just delivered a 4100-g boy after a 15-hour labor, including a 21/2-hour second stage. During the repair of a midline episiotomy, there is a marked increase in the amount of vaginal bleeding.

  Which of the following is the best immediate management of the probable cause of this postpartum hemorrhage?

  A. massage and compression of the uterine fundus

  B. intravenous administration of 20 units of oxytocin

  C. abdominal hysterectomy

  D. uterine artery embolization

  E. hypogastric artery ligation

  Correct Answer: A

  Immediate management is bimanual massage and compression of the uterine fundus by placing one fist into the anterior vaginal fornix and the other hand abdominally posterior to the uterus. The uterine massage is often enough to cause myometrial contractions and slowing of the bleeding. Oxytocin or an ergot alkaloid (e.g., methylergonovine) should then be administered if bimanual massage of the uterus is ineffective. Insertion of a gauze pack is never indicated because it is rarely effective. It may actually worsen the bleeding by preventing contraction of the myometrium. Persistent bleeding from the uterus despite these measures may indicate uterine rupture, retained placental fragments, or placenta accreta. If a careful curettage of the uterine lining fails to remove any placental fragments and decrease uterine bleeding, hypogastric artery ligation or a hysterectomy must be considered.

• Question 568:

  A 34-year-old woman just delivered a 4100-g boy after a 15-hour labor, including a 21/2-hour second stage. During the repair of a midline episiotomy, there is a marked increase in the amount of vaginal bleeding.

  Which of the following is the most common cause of immediate postpartum hemorrhage?

  A. retained placental fragments

  B. uterine atony

  C. cervical laceration

  D. vaginal laceration

  E. disseminated intravascular coagulation

  Correct Answer: B

  The main mechanism by which hemostasis is achieved following delivery is contraction of the myometrium to compress the uterine vessels that had been supplying the placenta. Lack of effective myometrial contraction (i.e., uterine atony) is the major cause of postpartum hemorrhage. If the uterus is found to be firmly contracted, then other factors, such as cervical or vaginal lacerations or a coagulopathy, must be sought.

• Question 569:

  When counseling pregnant women about the dangers of drug use during pregnancy, they should be told that the rate of spontaneous major malformations in newborns is what?

  A. less than 1%

  B. 24%

  C. 68%

  D. 1012%

  E. more than 12%

  Correct Answer: B

  Approximately 3% of live born infants have a major congenital anomaly detected at birth.The incidence increases to 67% later in childhood. Chromosomal and single-gene defects account for 10 25% of human malformations. Fetal infections (35%), maternal disease (4%), and drugs and medications (<1%) account for the remaining recognized causes of human malformations. Sixty-five to seventy-five percent of malformations have an unknown or multifactorial etiology

• Question 570:

  A pregnant woman has been taking phenytoin (Dilantin) for a seizure disorder. She is concerned that the drug will cause fetal abnormalities. Which of the following defects is the most common anomaly associated with phenytoin?

  A. atrial septal defect

  B. ventricular septal defect

  C. cleft lip/palate

  D. spina bifida

  E. hydrocephalus

  Correct Answer: C

  As many as 30% of fetuses exposed to phenytoin had minor craniofacial and digital anomalies. Cleft lip/ palate, hypertelorism, broad nasal bridge, and epicanthal folds are the craniofacial anomalies observed. Hypoplasia of the distal phalanges and nails are the digital anomalies. In addition, these infants may have growth and cognitive deficiencies. Trimethadione, another anticonvulsant, causes similar anomalies. Spina bifida occurs in 12% of infants whose mothers took valproic acid during pregnancy.