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USMLE Step 1 – High-Yield Practice Test (2026 | 2027 Style) Questions and
Answers with detailed Rationales | Updates | 100% Correct.
Domain 1: Pathology – General & Systemic
1. A 55-year-old male with a history of smoking presents with a 2-month history
of progressive dysphagia and weight loss. An esophagoscopy reveals a firm,
irregular mass in the lower third of the esophagus. Biopsy shows malignant
epithelial cells. What is the most likely diagnosis?
A) Esophageal adenocarcinoma (associated with Barrett's esophagus and GERD)
B) Esophageal squamous cell carcinoma (associated with smoking and alcohol)
C) Esophageal leiomyoma
D) Esophageal stricture
Answer: B
Rationale: Esophageal squamous cell carcinoma is strongly associated with
smoking and alcohol consumption. It typically occurs in the middle to lower third
of the esophagus. Adenocarcinoma is more common in the distal esophagus and is
associated with Barrett's esophagus (chronic GERD).
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2. A 68-year-old male presents with a 2-week history of bright red, painless
rectal bleeding and a change in bowel habits. Colonoscopy reveals a fungating
mass in the descending colon. Biopsy shows malignant glandular cells. What is
the most likely diagnosis?
A) Colorectal adenocarcinoma
B) Crohn's disease
C) Ulcerative colitis
D) Diverticulitis
Answer: A
Rationale: Colorectal adenocarcinoma is the most common type of colon cancer. It
presents with painless rectal bleeding, changes in bowel habits, and weight loss.
Risk factors include age, family history, and inflammatory bowel disease.
3. A 45-year-old female presents with a 3-month history of fatigue, weight loss,
and a non-productive cough. Chest X-ray reveals bilateral hilar
lymphadenopathy and reticular nodular opacities. A lung biopsy shows non-
caseating granulomas. What is the most likely diagnosis?
A) Tuberculosis
B) Sarcoidosis
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C) Histoplasmosis
D) Lung cancer
Answer: B
Rationale: Sarcoidosis is a multisystem granulomatous disease of unknown
etiology. Classic findings include: bilateral hilar lymphadenopathy, reticular
nodular opacities on CXR, and non-caseating granulomas on biopsy. It is more
common in African American females.
4. A 60-year-old male with a 20-year history of type 2 diabetes presents with a
4-day history of fever, chills, and right flank pain. Urinalysis shows WBCs, RBCs,
and bacteria. A CT scan shows a hypo-attenuating area in the renal parenchyma.
What is the most likely diagnosis?
A) Acute pyelonephritis
B) Renal calculi (kidney stones)
C) Renal cell carcinoma
D) Glomerulonephritis
Answer: A
Rationale: Acute pyelonephritis is a bacterial infection of the renal parenchyma.
Classic presentation includes: fever, chills, flank pain, and costovertebral angle
USMLE Step 1 – High-Yield Practice Test (2026 | 2027 Style) Questions and
Answers with detailed Rationales | Updates | 100% Correct.
Domain 1: Pathology – General & Systemic
1. A 55-year-old male with a history of smoking presents with a 2-month history
of progressive dysphagia and weight loss. An esophagoscopy reveals a firm,
irregular mass in the lower third of the esophagus. Biopsy shows malignant
epithelial cells. What is the most likely diagnosis?
A) Esophageal adenocarcinoma (associated with Barrett's esophagus and GERD)
B) Esophageal squamous cell carcinoma (associated with smoking and alcohol)
C) Esophageal leiomyoma
D) Esophageal stricture
Answer: B
Rationale: Esophageal squamous cell carcinoma is strongly associated with
smoking and alcohol consumption. It typically occurs in the middle to lower third
of the esophagus. Adenocarcinoma is more common in the distal esophagus and is
associated with Barrett's esophagus (chronic GERD).
, Page |2
2. A 68-year-old male presents with a 2-week history of bright red, painless
rectal bleeding and a change in bowel habits. Colonoscopy reveals a fungating
mass in the descending colon. Biopsy shows malignant glandular cells. What is
the most likely diagnosis?
A) Colorectal adenocarcinoma
B) Crohn's disease
C) Ulcerative colitis
D) Diverticulitis
Answer: A
Rationale: Colorectal adenocarcinoma is the most common type of colon cancer. It
presents with painless rectal bleeding, changes in bowel habits, and weight loss.
Risk factors include age, family history, and inflammatory bowel disease.
3. A 45-year-old female presents with a 3-month history of fatigue, weight loss,
and a non-productive cough. Chest X-ray reveals bilateral hilar
lymphadenopathy and reticular nodular opacities. A lung biopsy shows non-
caseating granulomas. What is the most likely diagnosis?
A) Tuberculosis
B) Sarcoidosis
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C) Histoplasmosis
D) Lung cancer
Answer: B
Rationale: Sarcoidosis is a multisystem granulomatous disease of unknown
etiology. Classic findings include: bilateral hilar lymphadenopathy, reticular
nodular opacities on CXR, and non-caseating granulomas on biopsy. It is more
common in African American females.
4. A 60-year-old male with a 20-year history of type 2 diabetes presents with a
4-day history of fever, chills, and right flank pain. Urinalysis shows WBCs, RBCs,
and bacteria. A CT scan shows a hypo-attenuating area in the renal parenchyma.
What is the most likely diagnosis?
A) Acute pyelonephritis
B) Renal calculi (kidney stones)
C) Renal cell carcinoma
D) Glomerulonephritis
Answer: A
Rationale: Acute pyelonephritis is a bacterial infection of the renal parenchyma.
Classic presentation includes: fever, chills, flank pain, and costovertebral angle
