10 USMLE General Pathology Questions with Answers and Explanations (Set 1)

These 10 USMLE general pathology practice questions cover cell adaptation, hypersensitivity, bleeding disorders, DNA repair defects, kidney and bladder cancers, plasma cell disorders, skin cancers, blistering diseases and chemical carcinogens. Each question includes the correct answer and an explanation.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. An 18-year-old man presents to the office for evaluation of multiple swellings in his neck. On examination, he has multiple large lymph nodes in his neck. Neurological examination reveals poor coordination on walking. Biopsy of lymph node is positive for lymphoma. He is diagnosed with ataxia-telangiectasia. What is the etiology of this disorder?

A- Defective DNA repair mechanisms
B- Deletion of VHL gene on chromosome 3
C- Mutation in the NF1 gene on chromosome 17
D- Mutation in PKD1 on chromosome 16
E- Mutation in APC gene on chromosome 5

A- Defective DNA repair mechanisms- Ataxia-telangiectasia is a recessive autosomal disorder caused by defective DNA repair mechanisms. It results in weakness of immune systems which leads to multiple infections and increasing risk of cancer. enzymes are all normal.
The correct answer is A

 

Question 2. Which one of the following conditions most likely occurs in a patient with thrombocytopenia?

A- Cerebral hemorrhage
B- Hemarthrosis
C- Petechiae
D- Subungual hemorrhage

C- Petechiae- It is the most common condition in a patient with thrombocytopenia. Other types of hemorrhages on the list most likely occur with hemophilia.
The correct answer is C

 

Question 3. Serum sickness involves which one of the following types of hypersensitivity?

A- Type 1 (IgE mediated reaction)
B- Type II (Antibody-mediated reaction)
C- Type III (Immune complex reaction)
D- Type IV (T-cell-mediated reaction)

C- Type III (Immune complex reaction)- Serum sickness involves an immune complex reaction and so, it is considered type III hypersensitivity. Other diseases involving type III of hypersensitivity are post-streptococcal glomerulonephritis, rheumatoid arthritis and systemic lupus erythematosus.
The correct answer is C

 

Question 4. Transplantation of the left lobe of liver is performed for a patient with hepatic failure. A year later, the size of the recipient liver becomes greater than at the time of the transplantation. Which one of the following cellular changes most likely takes place in the patient’s liver?

A- Anaplasia
B- Dysplasia
C- Hyperplasia
D- Metaplasia

C- Hyperplasia- Hepatocytes are stable cells and are able to re-enter the cell cycle and regenerate. The other choices are pathological changes.
The correct answer is C

 

Question 5. An autopsy is performed for an obese male died of a heart attack. Microscopic examination of the heart shows the myocardial fibers are increased in size and adipocytes are interdigitating with these fibers. Which of the following most likely explains the presence of adipocytes in the patient’s heart?

A- Cholesterol deposition
B- Fatty infiltration
C- Steatosis
D- Xanthomatosis

B- Fatty infiltration- This is a normal deposition of normal fat cells (adipocytes) in the tissues of obese persons.
The correct answer is B

 

Question 6. A 50-year-old man has noticed darker urine for the last week. There is no pain, discomfort or any other symptoms. Examination reveals no abnormalities. Urine analysis shows 2+blood, no glucose or protein. Urine cytology shows atypical cells. Cystoscopy shows no mucosal lesions of the urinary bladder. He has a 30-year history of smoking. Which of the following is the most likely diagnosis?

A- Adenocarcinoma of the prostate
B- Transitional cell (urothelial) carcinoma of the urinary bladder
C- Renal cell carcinoma

C- Renal cell carcinoma- It is the most common and smoking is a major risk. It manifests as hematuria which is usually accompanied by lower back pain.
The correct answer is C

 

Question 7. In a case of multiple myeloma, a sternal bone marrow sample is performed. Which of the following cell types is mostly found in this aspirate?

A- Giant cells
B- Fibroblasts
C- Osteoblasts
D- Plasma cells

D- Plasma cells- Serum globulin is also high in multiple myeloma due to monoclonal gammopathy. Other types of cells are just distractions.
The correct answer is D

 

Question 8. A 65-year-old farmer presents to the clinic for evaluation of a long time lesion on his forehead. During an examination for life insurance, the nurse noticed it and advised him to go to the clinic for evaluation. The lesion is 1.5 in diameter, tan and nodular with an adherent greasy scale. Microscopically, it shows atypical keratinocytes invading the dermis and presence of intercellular bridges between the tumor cells. What is the most likely diagnosis?

A- Basal cell carcinoma
B- Langerhans cell histiocytosis
C- Malignant melanoma
D- Mycosis fungoides
E- Squamous cell carcinoma

This is a typical presentation of squamous cell carcinoma. Forehead is a common site due to direct exposure to sun. Gross and microscopic findings are typical for squamous cell carcinoma.
The correct answer is E

 

Question 9. A 72-year-old man complains of itchy skin lesions in the axilla, groin and medial aspect of the thigh. Examination reveals pruritic lesions and bullae in the areas mentioned above and also on forearms and lower legs. There are no oral lesions. There is no eye involvement and Nikolsky sign is negative. What is the most likely diagnosis?

A- Pemphigus vulgaris
B- Bullous pemphigoid
C- Cicatricial pemphigoid
D- Scabies
E- Dermatitis herpetiformis

This lesion is most likely bullous pemphigoid. Absence of oral lesions, a negative Nikolsky sign besides the sites of the lesions confirm the diagnosis. This lesion is similar to pemphigus vulgaris except that Nikolsky’s sign is positive in the later. Cicatricial pemphigoid is a rare blistering disease characterized by scarring of the erosions of the mucous membranes. Scabies and dermatitis herpetiformis have clinical pictures different from this condition.
The correct answer is B

 

Question 10. Workers in the aniline dye industry are more susceptible to bladder cancer than general population. Meanwhile, studies show that animals, when exposed to beta-naphthylamine develop liver cancer but not bladder cancer. What is the most likely explanation of this finding?

A- Metabolism of beta-naphthylamine by human cytochrome 450 system in the liver
B- Detoxification of beta-naphthylamine by glucuronic acid conjugation.
C- Human urinary glucuronidase splits beta-naphthylamine into glucuronic acid and a toxic metabolite.
D- Beta-naphthylamine is directly carcinogenic to human bladder

Urinary glucuronidase is found only in human. It splits beta-naphthylamine into glucuronic acid and a toxic carcinogenic metabolite. This metabolite is the responsible agent for bladder cancer in human. Other options are distractions.
The correct answer is C

 

High-yield points from this set

  • Ataxia-telangiectasia = defective DNA repair (ATM gene), immunodeficiency and cancer risk.
  • Thrombocytopenia causes petechiae and mucosal bleeding; hemarthrosis suggests hemophilia.
  • Serum sickness is a type III (immune complex) hypersensitivity.
  • Liver regeneration after partial transplant is hyperplasia of stable hepatocytes.
  • Fat cells between heart muscle fibers in obesity = fatty infiltration.
  • Painless hematuria in a smoker with a normal cystoscopy: think renal cell carcinoma.
  • Multiple myeloma marrow is full of plasma cells.
  • Keratin pearls and intercellular bridges = squamous cell carcinoma.
  • Tense blisters, no oral lesions, negative Nikolsky sign in an older adult = bullous pemphigoid.
  • Aniline dye (beta-naphthylamine) exposure causes bladder cancer.

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