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NBME CBSE REAL EXAM 270 QUESTIONS AND ANSWERS LATEST
2026-2027 COMPLETE EXAM (USMLE STEP 1)MEDICAL
EXAMINATION 100% CORRECT ALREADY GRADED A+
Q1.
A 23-year-old man presents to the emergency department with sudden onset chest
pain and shortness of breath after lifting a heavy box. He is tall, thin, and has a
history of occasional smoking. On examination, there is decreased breath sounds
on the right, hyperresonance to percussion, and tracheal deviation to the left.
Which of the following is the most likely diagnosis?
A) Pulmonary embolism
B) Tension pneumothorax
C) Spontaneous bacterial pneumonia
D) Acute asthma exacerbation
E) Pericardial tamponade
Answer & Explanation:
👉 Correct = B. Tension pneumothorax.
The sudden unilateral chest pain, decreased breath sounds, hyperresonance, and
tracheal deviation point to tension pneumothorax. Other options don’t fit the acute
presentation with tracheal deviation.
Q2.
A 4-year-old boy is brought in with recurrent infections, chronic diarrhea, and
failure to thrive. His lab results show low immunoglobulin levels across all classes
and absent tonsils/lymph nodes on examination. Genetic testing reveals a defect in
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the BTK gene.
This patient’s condition most closely resembles which of the following?
A) Common variable immunodeficiency
B) Selective IgA deficiency
C) Bruton’s agammaglobulinemia
D) DiGeorge syndrome
E) Hyper-IgE syndrome
Answer & Explanation:
👉 Correct = C. Bruton’s agammaglobulinemia.
BTK gene defect = failure of B-cell maturation → no immunoglobulins, recurrent
bacterial infections, absent lymphoid tissue.
Q3.
A 45-year-old woman presents with progressive fatigue, pruritus, and jaundice. She
has no history of alcohol use. Physical examination shows hepatomegaly and
xanthelasma around the eyes. Labs reveal elevated alkaline phosphatase and
positive antimitochondrial antibodies.
Which of the following is the most likely diagnosis?
A) Primary sclerosing cholangitis
B) Autoimmune hepatitis
C) Primary biliary cholangitis
D) Alcoholic liver disease
E) Wilson’s disease
Answer & Explanation:
👉 Correct = C. Primary biliary cholangitis (PBC).
Middle-aged woman, pruritus, cholestatic pattern (↑ ALP), antimitochondrial
antibodies = PBC.
Q4.
A 60-year-old man presents with worsening cough and weight loss. He has a 40-
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pack-year smoking history. Imaging shows a central lung mass with cavitation.
Histology reveals keratin pearls and intercellular bridges.
Which of the following is the most likely type of lung cancer?
A) Adenocarcinoma
B) Small cell carcinoma
C) Squamous cell carcinoma
D) Large cell carcinoma
E) Carcinoid tumor
Answer & Explanation:
👉 Correct = C. Squamous cell carcinoma.
Smoking history + central location + keratin pearls = classic squamous cell
carcinoma.
Q5.
A 12-year-old boy presents with bone pain and a palpable mass in his left femur.
X-ray reveals a destructive lesion with a sunburst pattern and Codman’s triangle.
Biopsy shows malignant osteoblasts producing osteoid.
Which of the following is the most likely diagnosis?
A) Osteoid osteoma
B) Ewing sarcoma
C) Osteosarcoma
D) Chondrosarcoma
E) Giant cell tumor of bone
Answer & Explanation:
👉 Correct = C. Osteosarcoma.
Sunburst pattern, Codman’s triangle, adolescents → osteosarcoma.
Q21.
A 32-year-old woman presents with muscle weakness and difficulty climbing
stairs. She reports that her symptoms worsen at the end of the day but improve
after rest. Physical exam reveals ptosis and double vision when looking upward for
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a prolonged period. Edrophonium test improves her symptoms.
Which of the following is most likely the underlying pathophysiology?
A) Autoantibodies against presynaptic calcium channels
B) Autoantibodies against postsynaptic acetylcholine receptors
C) Demyelination of peripheral motor neurons
D) Deficiency of choline acetyltransferase
E) Mutation in dystrophin gene
Answer & Explanation:
👉 Correct = B. Autoantibodies against postsynaptic acetylcholine receptors →
Myasthenia gravis.
Q22.
A 45-year-old man with chronic alcohol use presents with confusion, ataxia, and
ophthalmoplegia. His diet consists mostly of beer, and he has lost weight recently.
Lab results show macrocytic anemia.
Which of the following vitamin deficiencies is most responsible for his
neurological findings?
A) Vitamin B1 (thiamine)
B) Vitamin B6 (pyridoxine)
C) Vitamin B9 (folate)
D) Vitamin B12 (cobalamin)
E) Vitamin C (ascorbic acid)
Answer & Explanation:
👉 Correct = A. Vitamin B1 (thiamine) → Wernicke encephalopathy (confusion,
ataxia, ophthalmoplegia).
Q23.
A 65-year-old man presents with worsening dyspnea and chronic cough producing
sputum. He has smoked two packs per day for 40 years. Physical exam reveals
cyanosis, clubbing, and bilateral wheezes. Pulmonary function tests show
NBME CBSE REAL EXAM 270 QUESTIONS AND ANSWERS LATEST
2026-2027 COMPLETE EXAM (USMLE STEP 1)MEDICAL
EXAMINATION 100% CORRECT ALREADY GRADED A+
Q1.
A 23-year-old man presents to the emergency department with sudden onset chest
pain and shortness of breath after lifting a heavy box. He is tall, thin, and has a
history of occasional smoking. On examination, there is decreased breath sounds
on the right, hyperresonance to percussion, and tracheal deviation to the left.
Which of the following is the most likely diagnosis?
A) Pulmonary embolism
B) Tension pneumothorax
C) Spontaneous bacterial pneumonia
D) Acute asthma exacerbation
E) Pericardial tamponade
Answer & Explanation:
👉 Correct = B. Tension pneumothorax.
The sudden unilateral chest pain, decreased breath sounds, hyperresonance, and
tracheal deviation point to tension pneumothorax. Other options don’t fit the acute
presentation with tracheal deviation.
Q2.
A 4-year-old boy is brought in with recurrent infections, chronic diarrhea, and
failure to thrive. His lab results show low immunoglobulin levels across all classes
and absent tonsils/lymph nodes on examination. Genetic testing reveals a defect in
,2 | Page
the BTK gene.
This patient’s condition most closely resembles which of the following?
A) Common variable immunodeficiency
B) Selective IgA deficiency
C) Bruton’s agammaglobulinemia
D) DiGeorge syndrome
E) Hyper-IgE syndrome
Answer & Explanation:
👉 Correct = C. Bruton’s agammaglobulinemia.
BTK gene defect = failure of B-cell maturation → no immunoglobulins, recurrent
bacterial infections, absent lymphoid tissue.
Q3.
A 45-year-old woman presents with progressive fatigue, pruritus, and jaundice. She
has no history of alcohol use. Physical examination shows hepatomegaly and
xanthelasma around the eyes. Labs reveal elevated alkaline phosphatase and
positive antimitochondrial antibodies.
Which of the following is the most likely diagnosis?
A) Primary sclerosing cholangitis
B) Autoimmune hepatitis
C) Primary biliary cholangitis
D) Alcoholic liver disease
E) Wilson’s disease
Answer & Explanation:
👉 Correct = C. Primary biliary cholangitis (PBC).
Middle-aged woman, pruritus, cholestatic pattern (↑ ALP), antimitochondrial
antibodies = PBC.
Q4.
A 60-year-old man presents with worsening cough and weight loss. He has a 40-
,3 | Page
pack-year smoking history. Imaging shows a central lung mass with cavitation.
Histology reveals keratin pearls and intercellular bridges.
Which of the following is the most likely type of lung cancer?
A) Adenocarcinoma
B) Small cell carcinoma
C) Squamous cell carcinoma
D) Large cell carcinoma
E) Carcinoid tumor
Answer & Explanation:
👉 Correct = C. Squamous cell carcinoma.
Smoking history + central location + keratin pearls = classic squamous cell
carcinoma.
Q5.
A 12-year-old boy presents with bone pain and a palpable mass in his left femur.
X-ray reveals a destructive lesion with a sunburst pattern and Codman’s triangle.
Biopsy shows malignant osteoblasts producing osteoid.
Which of the following is the most likely diagnosis?
A) Osteoid osteoma
B) Ewing sarcoma
C) Osteosarcoma
D) Chondrosarcoma
E) Giant cell tumor of bone
Answer & Explanation:
👉 Correct = C. Osteosarcoma.
Sunburst pattern, Codman’s triangle, adolescents → osteosarcoma.
Q21.
A 32-year-old woman presents with muscle weakness and difficulty climbing
stairs. She reports that her symptoms worsen at the end of the day but improve
after rest. Physical exam reveals ptosis and double vision when looking upward for
, 4 | Page
a prolonged period. Edrophonium test improves her symptoms.
Which of the following is most likely the underlying pathophysiology?
A) Autoantibodies against presynaptic calcium channels
B) Autoantibodies against postsynaptic acetylcholine receptors
C) Demyelination of peripheral motor neurons
D) Deficiency of choline acetyltransferase
E) Mutation in dystrophin gene
Answer & Explanation:
👉 Correct = B. Autoantibodies against postsynaptic acetylcholine receptors →
Myasthenia gravis.
Q22.
A 45-year-old man with chronic alcohol use presents with confusion, ataxia, and
ophthalmoplegia. His diet consists mostly of beer, and he has lost weight recently.
Lab results show macrocytic anemia.
Which of the following vitamin deficiencies is most responsible for his
neurological findings?
A) Vitamin B1 (thiamine)
B) Vitamin B6 (pyridoxine)
C) Vitamin B9 (folate)
D) Vitamin B12 (cobalamin)
E) Vitamin C (ascorbic acid)
Answer & Explanation:
👉 Correct = A. Vitamin B1 (thiamine) → Wernicke encephalopathy (confusion,
ataxia, ophthalmoplegia).
Q23.
A 65-year-old man presents with worsening dyspnea and chronic cough producing
sputum. He has smoked two packs per day for 40 years. Physical exam reveals
cyanosis, clubbing, and bilateral wheezes. Pulmonary function tests show
