NBME CBSE (USMLE STEP 1) 2026-2027: THE ULTIMATE
HIGH-YIELD TEST BANK 180 NGN-Style Clinical Vignette
Questions with Evidence-Based Rationales | Derived from
NBME Comprehensive Basic Science Examination
Content Outline | Guaranteed A+ on Your First Attempt
This test bank includes 50 of the most difficult, frequently tested questions
that students consistently miss on the NBME CBSE. Master these, and you'll
pass with confidence!
SECTION 1: GENERAL PRINCIPLES OF PATHOLOGY (Questions 1-22)
Q1. A 58-year-old male with a 40-pack-year smoking history presents with a
persistent cough and weight loss. A chest CT reveals a 3 cm mass in the
right upper lobe. Biopsy shows malignant cells with keratin pearls and
intercellular bridges. Which of the following genetic mutations is MOST
commonly associated with this type of malignancy?
A) KRAS mutation
B) EGFR mutation
C) TP53 mutation
D) ALK rearrangement
E) BRAF V600E mutation
,Correct Answer: C
Rationale:This patient has squamous cell carcinoma of the lung,
characterized by keratin pearls and intercellular bridges. TP53
mutations*are the most common genetic alteration in squamous cell lung
cancer, occurring in approximately 50-70% of cases. KRAS mutations are
more common in adenocarcinoma. EGFR mutations and ALK
rearrangements are also more characteristic of adenocarcinoma,
particularly in non-smokers. BRAF V600E is associated with melanoma,
colorectal cancer, and hairy cell leukemia.
Q2. A 45-year-old woman with a history of systemic lupus erythematosus
presents with fatigue, weight loss, and a malar rash. Laboratory studies
reveal proteinuria and hematuria. A renal biopsy shows diffuse thickening
of the glomerular basement membrane with a "wire-loop" appearance on
light microscopy. Which of the following is the MOST likely mechanism of
injury in this patient's renal disease?
A) Type I hypersensitivity reaction
B) Type II hypersensitivity reaction
C) Type III hypersensitivity reaction
D) Type IV hypersensitivity reaction
E) Type V hypersensitivity reaction
,Correct Answer: C
Rationale: This patient has class V lupus nephritis (membranous lupus
nephritis), characterized by diffuse thickening of the glomerular basement
membrane and "wire-loop" lesions. The underlying mechanism is a **Type
III hypersensitivity reaction**, involving the deposition of immune
complexes (antigen-antibody complexes) in the glomerular basement
membrane. Type I is IgE-mediated (anaphylaxis). Type II is antibody-
mediated (cytotoxic). Type IV is T-cell mediated (delayed-type
hypersensitivity). Type V is antibody-mediated (stimulatory).
Q3.A 72-year-old male presents with progressive difficulty swallowing, first
with solids and now with liquids. He reports a 20-pound unintentional
weight loss over the past 3 months. An upper endoscopy reveals a mass in
the mid-esophagus. Biopsy shows malignant cells with glandular formation.
Which of the following risk factors is MOST strongly associated with this
condition?
A) Human papillomavirus infection
B) Gastroesophageal reflux disease with Barrett esophagus
C) Alcohol consumption
D) Tobacco use
E) Achalasia
Correct Answer: B
, Rationale: This patient has esophageal adenocarcinoma, which arises from
Barrett esophagus (intestinal metaplasia of the esophageal mucosa).
Gastroesophageal reflux disease (GERD) with Barrett esophagus is the
strongest risk factor for esophageal adenocarcinoma. The incidence of
adenocarcinoma has been increasing, particularly in Western countries.
Barrett esophagus results from chronic acid exposure leading to
metaplastic change from stratified squamous to columnar epithelium. HPV
infection, alcohol, and tobacco are more strongly associated with
squamous cell carcinoma of the esophagus. Achalasia is a risk factor for
squamous cell carcinoma.
Q4. A 28-year-old woman presents with a painless, firm, rubbery mass in
the upper outer quadrant of her right breast. She reports that the mass is
mobile and not fixed to the underlying tissue. A fine-needle aspiration
shows benign cells. Which of the following is the MOST likely diagnosis?
A) Infiltrating ductal carcinoma
B) Fibroadenoma
C) Phyllodes tumor
D) Intraductal papilloma
E) Fat necrosis
Correct Answer: B
HIGH-YIELD TEST BANK 180 NGN-Style Clinical Vignette
Questions with Evidence-Based Rationales | Derived from
NBME Comprehensive Basic Science Examination
Content Outline | Guaranteed A+ on Your First Attempt
This test bank includes 50 of the most difficult, frequently tested questions
that students consistently miss on the NBME CBSE. Master these, and you'll
pass with confidence!
SECTION 1: GENERAL PRINCIPLES OF PATHOLOGY (Questions 1-22)
Q1. A 58-year-old male with a 40-pack-year smoking history presents with a
persistent cough and weight loss. A chest CT reveals a 3 cm mass in the
right upper lobe. Biopsy shows malignant cells with keratin pearls and
intercellular bridges. Which of the following genetic mutations is MOST
commonly associated with this type of malignancy?
A) KRAS mutation
B) EGFR mutation
C) TP53 mutation
D) ALK rearrangement
E) BRAF V600E mutation
,Correct Answer: C
Rationale:This patient has squamous cell carcinoma of the lung,
characterized by keratin pearls and intercellular bridges. TP53
mutations*are the most common genetic alteration in squamous cell lung
cancer, occurring in approximately 50-70% of cases. KRAS mutations are
more common in adenocarcinoma. EGFR mutations and ALK
rearrangements are also more characteristic of adenocarcinoma,
particularly in non-smokers. BRAF V600E is associated with melanoma,
colorectal cancer, and hairy cell leukemia.
Q2. A 45-year-old woman with a history of systemic lupus erythematosus
presents with fatigue, weight loss, and a malar rash. Laboratory studies
reveal proteinuria and hematuria. A renal biopsy shows diffuse thickening
of the glomerular basement membrane with a "wire-loop" appearance on
light microscopy. Which of the following is the MOST likely mechanism of
injury in this patient's renal disease?
A) Type I hypersensitivity reaction
B) Type II hypersensitivity reaction
C) Type III hypersensitivity reaction
D) Type IV hypersensitivity reaction
E) Type V hypersensitivity reaction
,Correct Answer: C
Rationale: This patient has class V lupus nephritis (membranous lupus
nephritis), characterized by diffuse thickening of the glomerular basement
membrane and "wire-loop" lesions. The underlying mechanism is a **Type
III hypersensitivity reaction**, involving the deposition of immune
complexes (antigen-antibody complexes) in the glomerular basement
membrane. Type I is IgE-mediated (anaphylaxis). Type II is antibody-
mediated (cytotoxic). Type IV is T-cell mediated (delayed-type
hypersensitivity). Type V is antibody-mediated (stimulatory).
Q3.A 72-year-old male presents with progressive difficulty swallowing, first
with solids and now with liquids. He reports a 20-pound unintentional
weight loss over the past 3 months. An upper endoscopy reveals a mass in
the mid-esophagus. Biopsy shows malignant cells with glandular formation.
Which of the following risk factors is MOST strongly associated with this
condition?
A) Human papillomavirus infection
B) Gastroesophageal reflux disease with Barrett esophagus
C) Alcohol consumption
D) Tobacco use
E) Achalasia
Correct Answer: B
, Rationale: This patient has esophageal adenocarcinoma, which arises from
Barrett esophagus (intestinal metaplasia of the esophageal mucosa).
Gastroesophageal reflux disease (GERD) with Barrett esophagus is the
strongest risk factor for esophageal adenocarcinoma. The incidence of
adenocarcinoma has been increasing, particularly in Western countries.
Barrett esophagus results from chronic acid exposure leading to
metaplastic change from stratified squamous to columnar epithelium. HPV
infection, alcohol, and tobacco are more strongly associated with
squamous cell carcinoma of the esophagus. Achalasia is a risk factor for
squamous cell carcinoma.
Q4. A 28-year-old woman presents with a painless, firm, rubbery mass in
the upper outer quadrant of her right breast. She reports that the mass is
mobile and not fixed to the underlying tissue. A fine-needle aspiration
shows benign cells. Which of the following is the MOST likely diagnosis?
A) Infiltrating ductal carcinoma
B) Fibroadenoma
C) Phyllodes tumor
D) Intraductal papilloma
E) Fat necrosis
Correct Answer: B
