13 USMLE Pathology, Hematology and Genetics Quick Review Questions with Answers (Set 7)

These 13 quick USMLE review questions test high-yield facts that show up again and again on the exam: pneumonia organisms, tuberculosis, cystic fibrosis, thalassemia, phenylketonuria, Paget disease, fat necrosis, celiac disease, meningitis, iron deficiency, xeroderma pigmentosum, lupus thrombocytopenia and schistosomiasis. Each question includes the correct answer.

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. Which of the following is the most common bacterium found in community-acquired pneumonia?

A- Chlamydia
B- Mycoplasma
C- Staphylococcus aureus
D- Streptococcus pneumoniae

D- Streptococcus pneumoniae- It is the common bacterium involved in community-acquired pneumonia. Other types of bacteria can cause pneumonia but not as common as pneumococcus.
The correct answer is D

 

Question 2. Which of the following is the reason that secondary tuberculosis often causes cavities in the apex of the lung, rather than the base?

A- Better perfused
B- Higher PO2
C- More acidic
D- More alveolar macrophages

B- Higher PO2- This is a favor environment for Mycobacterium TB leading to reactivation of old TB infection. Apex of the lung is less acidic than the base.
The correct answer is B

 

Question 3. Which one of the following pulmonary conditions is commonly associated with cystic fibrosis?

A- Adenocarcinoma
B- Bronchiectasis
C- Pleural fibrous plaques
D- Pneumothorax

B- Bronchiectasis- Sweat chloride is diagnostic test for cystic fibrosis. CF leads to development of multiple lung infections which lead to inflammation, obstruction, dilation and destruction of bronchi leading to bronchiectasis.
The correct answer is B

 

Question 4. Normal iron studies most likely suggest which one of the following types of anemia?

A- Iron deficiency anemia
B- Sideroblastic anemia
C- Thalassemia

C- Thalassemia- It is a genetic disease that shows normal iron studies. Iron deficiency anemia is characterized by low serum iron level. Sideroblastic anemia is the only type of microcytic anemia that shows high serum iron level.
The correct answer is C

 

Question 5. Phenylketonuria occurs due to a deficiency of which one of the following enzymes?

A- Dopamine B-hydroxylase
B- Phenylalanine decarboxylase
C- Phenylalanine hydroxylase
D- Tyrosine hydroxylase

C- Phenylalanine hydroxylase- Deficiency of this enzyme leads to decreased metabolism of phenylalanine which results in accumulation of this amino acid. It leads to intellectual disabilities and seizures.
The correct answer is C

 

Question 6. Which one of the following conditions is characterized by bone pain, bone enlargement, and arthritis?

A- Osteoarthritis
B- Osteomalacia
C- Paget disease of bone
D- Rickets

C- Paget disease of bone- It is characterized by both osteoblastic and osteoclastic activity. It leads to excessive bone breakdown and disorganized bone formation which results in pain, deformity, and fracture. It commonly affects the skull, lumber vertebra, pelvis, femur, and tibia.
The correct answer is C

 

Question 7. Which one of the following types of necrosis mostly occurs in cases of acute pancreatitis?

A- Caseous necrosis
B- Coagulative necrosis
C- Fat necrosis
D- Fibrinoid necrosis

C- Fat necrosis- Damage of pancreatic cells leads to release of lipase which breaks down tissue triglycerides causing saponification. It is an enzymatic type of fat necrosis.
The correct answer is C

 

Question 8. Which one of the following conditions is characterized by the detection of atrophied villi on an intestinal biopsy?

A- Celiac disease
B- Crohn’s disease
C- Lactose intolerance
D- Ulcerative colitis

The correct answer is A. Celiac disease is a chronic disorder caused by immune reaction to gluten which is found in some foods such as wheat, rye and barley. Symptoms include diarrhea, abdominal pain, weakness, and fatigue. Anti-tissue transglutaminase antibody is diagnostic, but biopsy is needed to confirm it.

 

Question 9. Which of the following is the most common causative organism of bacterial meningitis in elderly patients?

A- Escherichia Coli
B- Listeria monocytogenes
C- Neisseria meningitidis
D- Streptococcus pneumoniae

The correct answer is D- S. pneumonia is the most common cause of meningitis in elderly patients. L. monocytogenes is the most common cause in newborns while N. meningitidis is the most common cause of meningitidis in kids and teens.

 

Question 10. A 30-year-old female presents with fatigue, pale skin, and shortness of breath. Laboratory results reveal a low hemoglobin level, low mean corpuscular volume (MCV), and an elevated red cell distribution width (RDW). Peripheral blood smear shows microcytic, hypochromic red blood cells. Which of the following is the most likely diagnosis?

A- Anemia of chronic disease
B- Folate deficiency anemia
C- Iron-deficiency anemia
D- Thalassemia
E- Vitamin B12 deficiency anemia

C- Iron deficiency anemia- This patient is likely experiencing iron-deficiency anemia. The symptoms include feeling tired, having pale skin, and difficulty breathing. Lab results show low hemoglobin, small red blood cells, and a higher-than-normal red cell distribution width. The appearance of small and pale red blood cells on a blood smear supports the diagnosis. Other types of anemia, caused by vitamin B12 or folate deficiency, may have larger red blood cells. Thalassemia, a genetic condition, and anemia of chronic disease is less likely based on the lab results.
The correct answer is C

 

Question 11. A 7-year-old girl is brought to the clinic by her parents due to severe sunburns after minimal sun exposure. She has also developed freckle-like pigmented lesions on her face and arms. A skin biopsy shows dysplastic keratinocytes and a paucity of melanocytes. What is the most likely diagnosis?

A- Albinism
B- Atopic dermatitis
C- Neurofibromatosis
D- Tuberous sclerosis
E- Xeroderma pigmentosa

E- Xeroderma pigmentosa- It is a rare genetic disorder that causes extreme sensitivity to ultraviolet (UV) light. Patients often experience severe sunburns after minimal sun exposure. Freckle-like pigmented lesions on sun-exposed areas are a characteristic feature. The defect in DNA repair mechanisms, particularly the excision repair enzymes, leads to dysplastic keratinocytes and a paucity of melanocytes.
The correct answer is E

 

Question 12. A 50-year-old woman presents with bleeding gums and joints pain for the last 24 hours. She has a history of systemic lupus erythematosus. Her platelet count is 20,000. Which of the following is the appropriate next step in management?

A- Methotrexate therapy
B- Plasmapheresis
C- Prednisone therapy
D- Splenectomy

C- Prednisone therapy- This is most likely a case of thrombocytopenia related to lupus. The initial treatment of an active episode is prednisone. In cases of refractory episodes of ITP, splenectomy is recommended.
The correct answer is C

 

Question 13. A 30-year-old man presents to the office for progressive pain with urination for 1 year. He also complains of episodes of blood in urine in different occasions. He lived in Egypt until he came to the states 6 months ago. Physical examination reveals suprapubic tenderness. Imaging shows bilateral hydroureter and hydronephrosis and calcification in the region of the bladder. A biopsy of the bladder shows chronic inflammation with fibrosis and granulomas. Which of the following is the most likely diagnosis?

A- Chronic pyelonephritis
B- Interstitial cystitis
C- Schistosomiasis
D- Systemic lupus erythematosus

C- Schistosomiasis- It is endemic in Northern Africa mainly in Egypt. It is associated with chronic cystitis and calcification of the bladder seen in x-ray is pathognomonic.
The correct answer is C

 

High-yield points from this set

  • Streptococcus pneumoniae is the most common cause of community-acquired pneumonia.
  • Secondary TB cavitates in the apices, where oxygen tension is highest.
  • Phenylketonuria = phenylalanine hydroxylase deficiency.
  • Acute pancreatitis causes fat necrosis.

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