NBME Practice MCB Questions and
answers from 1-200
,A 2 year old girl who is exposed to the sun has progressive development of dryness of the skin, excessive
freckling, and keratoses. Skin fibroblasts cultured from this child are most likely to be defective in which
of the following? - CORRECT ANS:Nuclear excision repair of pyrimidine dimers
a 65 year old man has a radical prostacetomy and lymph node dissection for adenocarcinoma of the
prostate. which of the following features is involved in the grading of this neoplasm - CORRECT
ANS:Tumor size
A man with a fair complexion develops an ulcerated nodule on his face after prolonged exposure to
sunlight. Examination of tissue obtained on excision of the nodule shows invasive squamous cell
carcinoma. Which of the following types of DNA damage is most likely responsible for this leason? -
CORRECT ANS:Pyrimidine dimers
A 45 year old woman with cancer is undergoing an intensive 2 week course of chemotherapy with
vinblastine. Which of the following changes is most likely to occur by the end of this treatment? -
CORRECT ANS:Decreased number of neutrophils - vinblastin mechanism is to bind microtubular proteins
in the mitotic spindle, thereby preventing cell division during metaphase. (anaphase promoting complex
inhibitor)
An 11 year old boy has had pain in his right mid thigh for 2 weeks. Physical examination shows an area
of warmth and tenderness around an ill defined mass. X ray of the femure shows a solitary mid
diaphyseal osteolytic lesion with permeative margins. The lesion is surrounded by concentric layers of
reactive bone. Tissue obtained on biosy of the mass is composed of poorly differentiated sheets of small,
uniform, hyperchromatic cells with a very high nuclear cytoplasmic ratio, scant stroma, and no visible
matrix. Which of the following is the most likely diagnosis? - CORRECT ANS:Ewing sarcoma - Ewing
sarcoma is a type of cancer that may be a bone sarcoma or a soft-tissue sarcoma. Symptoms may
include swelling and pain at the site of the tumor, fever, and a bone fracture.
a 55 year old woman with colon cancer and a healthy 55 year old woman are participating in a study of
colon cancer. malignant cells are obtained from the tumor in the affect patient, and normal colonic
epithelial cells are procured from the healthy subject. After both cell tpyes are treated with transforming
growth factor B, the number of normal cells decreases whereas the number of tumor cells remains
unchanged. The tumor cells most likely express a mutation that inhibits which of the following
physiological processes. - CORRECT ANS:Apoptosis
, A 10 month old boy has an abdominal mass noted during a routine physical examination. Abdominal
ultrasonography shows a 10 cm solid mass on the upper pole of the left kidney. Angiographically, the
mass is hypervascular. Which of the following is the most likely diagnosis? - CORRECT
ANS:Nephroblastoma (Wilms Tumor)
A 52 year old man comes to the physician because of a 3 month hisotry of epigastric abdominal painl; he
used to live in japan, is a smokr and drinks three to four glasses of wine daily. Physical exam shows
epigastric tenderness. Upper gastrointestinal endoscopy shows a 4 cm ulcer in the stomach.
Examination of a biosy specimen of the lesion confirms adenocarinoma. Which of the following is the
strongest predisposing risk factor for the patient's condition? - CORRECT ANS:Diet
An investigator conducts a study of the molecular basis of von Hippel lindau disease, specifically the role
of the VHL protein in the disease process. The protein forms part of a ubiquitin ligase complex (E3) that
targets hypoxia- inducible factor -1. The pathway is shown in the diagram. Step IV most likely involves
which of the following organelles? - CORRECT ANS:Proteasome
A 28 year old man is diagnosed with advanced testicular cancer. Combination chemotherapy is being
considered. Cisplatin is included in the regimen because of its effect on which of the following? -
CORRECT ANS:DNA
A study is conducted of breast cancer cell invasion of surrounding tissues and metastasis. Two breast
cancer cell lines, in the presence and absence of macrophages are analyzed. The macrophages are found
to secrete a protein that is essential for invasion and metastasis. This protein is most likely which of the
following? - CORRECT ANS:Metalloproteinases (MMPS)
An investigator is studying the effect of paclitaxel on the growth of breast cancer cells. The investigator
observes that the drug binds to microtubules. This binding will interfere with the completion of which of
the following stages of the cell cycle? - CORRECT ANS:M phase
A 3 year old boy is brought to the physician because of episodes of sunburn after brief sun exposure
during the past 18 months. Typically, the sunburn persisted for more than 2 weeks. A 12 year old cousin
has basal cell carinoma. Physical examination shows numerous freckles and erythamatous, scaly, rough
answers from 1-200
,A 2 year old girl who is exposed to the sun has progressive development of dryness of the skin, excessive
freckling, and keratoses. Skin fibroblasts cultured from this child are most likely to be defective in which
of the following? - CORRECT ANS:Nuclear excision repair of pyrimidine dimers
a 65 year old man has a radical prostacetomy and lymph node dissection for adenocarcinoma of the
prostate. which of the following features is involved in the grading of this neoplasm - CORRECT
ANS:Tumor size
A man with a fair complexion develops an ulcerated nodule on his face after prolonged exposure to
sunlight. Examination of tissue obtained on excision of the nodule shows invasive squamous cell
carcinoma. Which of the following types of DNA damage is most likely responsible for this leason? -
CORRECT ANS:Pyrimidine dimers
A 45 year old woman with cancer is undergoing an intensive 2 week course of chemotherapy with
vinblastine. Which of the following changes is most likely to occur by the end of this treatment? -
CORRECT ANS:Decreased number of neutrophils - vinblastin mechanism is to bind microtubular proteins
in the mitotic spindle, thereby preventing cell division during metaphase. (anaphase promoting complex
inhibitor)
An 11 year old boy has had pain in his right mid thigh for 2 weeks. Physical examination shows an area
of warmth and tenderness around an ill defined mass. X ray of the femure shows a solitary mid
diaphyseal osteolytic lesion with permeative margins. The lesion is surrounded by concentric layers of
reactive bone. Tissue obtained on biosy of the mass is composed of poorly differentiated sheets of small,
uniform, hyperchromatic cells with a very high nuclear cytoplasmic ratio, scant stroma, and no visible
matrix. Which of the following is the most likely diagnosis? - CORRECT ANS:Ewing sarcoma - Ewing
sarcoma is a type of cancer that may be a bone sarcoma or a soft-tissue sarcoma. Symptoms may
include swelling and pain at the site of the tumor, fever, and a bone fracture.
a 55 year old woman with colon cancer and a healthy 55 year old woman are participating in a study of
colon cancer. malignant cells are obtained from the tumor in the affect patient, and normal colonic
epithelial cells are procured from the healthy subject. After both cell tpyes are treated with transforming
growth factor B, the number of normal cells decreases whereas the number of tumor cells remains
unchanged. The tumor cells most likely express a mutation that inhibits which of the following
physiological processes. - CORRECT ANS:Apoptosis
, A 10 month old boy has an abdominal mass noted during a routine physical examination. Abdominal
ultrasonography shows a 10 cm solid mass on the upper pole of the left kidney. Angiographically, the
mass is hypervascular. Which of the following is the most likely diagnosis? - CORRECT
ANS:Nephroblastoma (Wilms Tumor)
A 52 year old man comes to the physician because of a 3 month hisotry of epigastric abdominal painl; he
used to live in japan, is a smokr and drinks three to four glasses of wine daily. Physical exam shows
epigastric tenderness. Upper gastrointestinal endoscopy shows a 4 cm ulcer in the stomach.
Examination of a biosy specimen of the lesion confirms adenocarinoma. Which of the following is the
strongest predisposing risk factor for the patient's condition? - CORRECT ANS:Diet
An investigator conducts a study of the molecular basis of von Hippel lindau disease, specifically the role
of the VHL protein in the disease process. The protein forms part of a ubiquitin ligase complex (E3) that
targets hypoxia- inducible factor -1. The pathway is shown in the diagram. Step IV most likely involves
which of the following organelles? - CORRECT ANS:Proteasome
A 28 year old man is diagnosed with advanced testicular cancer. Combination chemotherapy is being
considered. Cisplatin is included in the regimen because of its effect on which of the following? -
CORRECT ANS:DNA
A study is conducted of breast cancer cell invasion of surrounding tissues and metastasis. Two breast
cancer cell lines, in the presence and absence of macrophages are analyzed. The macrophages are found
to secrete a protein that is essential for invasion and metastasis. This protein is most likely which of the
following? - CORRECT ANS:Metalloproteinases (MMPS)
An investigator is studying the effect of paclitaxel on the growth of breast cancer cells. The investigator
observes that the drug binds to microtubules. This binding will interfere with the completion of which of
the following stages of the cell cycle? - CORRECT ANS:M phase
A 3 year old boy is brought to the physician because of episodes of sunburn after brief sun exposure
during the past 18 months. Typically, the sunburn persisted for more than 2 weeks. A 12 year old cousin
has basal cell carinoma. Physical examination shows numerous freckles and erythamatous, scaly, rough
