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(Created page with "{{WBRQuestion |QuestionAuthor={{Ochuko}} |ExamType=USMLE Step 1 |MainCategory=Pathology |SubCategory=Pulmonology, General Principles |MainCategory=Pathology |SubCategory=Pulmo...")
 
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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Ochuko}}
|QuestionAuthor={{Ochuko}} {{Alison}}
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pathology
|MainCategory=Pathology
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|MainCategory=Pathology
|MainCategory=Pathology
|SubCategory=Pulmonology, General Principles
|SubCategory=Pulmonology, General Principles
|Prompt=A 34- year old man presents to the physician’s office with a 3-month history of cough, night sweats and weight loss. Past medical history is unremarkable. Physical examination, chest X ray and Sputum AFB confirms Mycobacterium tuberculosis. Which one of the following would be a step in the sequence of formation of a tuberculous granuloma in this patient?
|Prompt=A 34-year-old male presents to the physician’s office with a 3-month history of cough, night sweats, and weight loss. Physical examination, a chest X ray, and Sputum AFB confirm ''Mycobacterium tuberculosis''. Which of the following would be a step in the formation of a tuberculous granuloma in this patient?
|Explanation=Tuberculous granuloma formation is a specialized form of chronic inflammation which is either caused by infections such as Tuberculosis and systemic fungal infections or non-infectious such as Sarcoidosis and Crohn’s disease. The sequence of steps includes:
|Explanation=Tuberculous granuloma formation is a specialized form of chronic inflammation which is either caused by infections such as Tuberculosis or systemic fungal infections or by non-infectious causes such as Sarcoidosis or Crohn’s disease.  
* The tubercle bacillus Mycobacterium tuberculosis undergoes phagocytosis by alveolar macrophages (processing of bacterial antigen)
* Macrophages present antigen to CD4  T cells in association with class II antigen sites
* Macrophages release IL 12 which stimulates the formation of TH1 class cells and IL 1 which causes fever; and activates TH1 cells
* TH1 cells release IL 2, gamma interferon and migration inhibitory factor
* Lipids from killed tubercle bacillus lead to caseous necrosis
* Activated macrophages fuse and become multinucleated giant cells


Reference: Goljan Rapid Review 2nd edition Pg 32
The sequence of [[tuberculous granuloma]] formation:
* Tubercle bacillus ''Mycobacterium tuberculosis'' undergoes phagocytosis by alveolar macrophages (processing of bacterial antigen).
* Macrophages present the antigen to CD4  T cells in association with class II antigen sites.
* Macrophages release IL-12 which stimulates the formation of TH1 class cells and IL-1, which causes fever, and activates TH1 cells.
* TH1 cells release IL-2, gamma interferon, and migration inhibitory factors.
* Lipids from killed tubercle bacillus result in [[caseous necrosis]].
* Activated macrophages fuse and become multinucleated giant cells.
 
|EducationalObjectives= Tuberculous granuloma formation is a specialized form of chronic inflammation which is either caused by infections such as Tuberculosis or systemic fungal infections or by non-infectious causes such as Sarcoidosis or Crohn’s disease.
 
|References= Goljan Rapid Review 2nd edition Pg 32


|AnswerA=The tubercle bacillus undergoes necrosis by alveolar macrophages
|AnswerA=The tubercle bacillus undergoes necrosis by alveolar macrophages
|AnswerAExp=Incorrect. The tubercle bacillus undergoes phagocytosis and not necrosis by alveolar macrophages
|AnswerAExp= The tubercle bacillus undergoes phagocytosis, but not necrosis, by alveolar macrophages
|AnswerB=The tubercle bacillus undergoes phagocytosis by alveolar macrophages
|AnswerB=The tubercle bacillus undergoes phagocytosis by alveolar macrophages
|AnswerBExp=Correct- See explanation
|AnswerBExp= See explanation
|AnswerC=Macrophages release IL-4 and IL 2
|AnswerC=Macrophages release IL-4 and IL-2
|AnswerCExp=Incorrect. IL-12 and not IL 4 stimulate the formation of the TH1 cells and then IL 1 and not IL 2 activates the TH1 cells and causes fever
|AnswerCExp= IL-12, not IL-4, stimulates the formation of the TH1 cells and then IL-1, not IL-2, activates the TH1 cells and leads to fever.
 
 
|AnswerD=Enzymes from killed tubercle bacillus lead to caseous necrosis
|AnswerD=Enzymes from killed tubercle bacillus lead to caseous necrosis
|AnswerDExp=Incorrect. Lipids and not enzymes from the killed bacillus lead to caseous necrosis
|AnswerDExp= Lipids, not enzymes, from the killed bacillus lead to caseous necrosis.
|AnswerE=Activated neutrophils fuse to become multinucleated giant cells
|AnswerE=Activated neutrophils fuse to become multinucleated giant cells
|AnswerEExp=Incorrect. Activated macrophages fuse, not neutrophils to become multinucleated giant cells.
|AnswerEExp= Activated macrophages, not neutrophils, fuse to become multinucleated giant cells.
|RightAnswer=B
|RightAnswer=B
|Approved=Yes
|Approved=Yes
}}
}}

Revision as of 18:34, 8 July 2014
Author [[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1] (Reviewed by Alison Leibowitz)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pathology
Sub Category SubCategory::Pulmonology, SubCategory::General Principles
Prompt [[Prompt::A 34-year-old male presents to the physician’s office with a 3-month history of cough, night sweats, and weight loss. Physical examination, a chest X ray, and Sputum AFB confirm Mycobacterium tuberculosis. Which of the following would be a step in the formation of a tuberculous granuloma in this patient?]]
Answer A AnswerA::The tubercle bacillus undergoes necrosis by alveolar macrophages
Answer A Explanation AnswerAExp::The tubercle bacillus undergoes phagocytosis, but not necrosis, by alveolar macrophages
Answer B AnswerB::The tubercle bacillus undergoes phagocytosis by alveolar macrophages
Answer B Explanation AnswerBExp::See explanation
Answer C AnswerC::Macrophages release IL-4 and IL-2
Answer C Explanation AnswerCExp::IL-12, not IL-4, stimulates the formation of the TH1 cells and then IL-1, not IL-2, activates the TH1 cells and leads to fever.
Answer D AnswerD::Enzymes from killed tubercle bacillus lead to caseous necrosis
Answer D Explanation AnswerDExp::Lipids, not enzymes, from the killed bacillus lead to caseous necrosis.
Answer E AnswerE::Activated neutrophils fuse to become multinucleated giant cells
Answer E Explanation AnswerEExp::Activated macrophages, not neutrophils, fuse to become multinucleated giant cells.
Right Answer RightAnswer::B
Explanation [[Explanation::Tuberculous granuloma formation is a specialized form of chronic inflammation which is either caused by infections such as Tuberculosis or systemic fungal infections or by non-infectious causes such as Sarcoidosis or Crohn’s disease.

The sequence of tuberculous granuloma formation:

  • Tubercle bacillus Mycobacterium tuberculosis undergoes phagocytosis by alveolar macrophages (processing of bacterial antigen).
  • Macrophages present the antigen to CD4 T cells in association with class II antigen sites.
  • Macrophages release IL-12 which stimulates the formation of TH1 class cells and IL-1, which causes fever, and activates TH1 cells.
  • TH1 cells release IL-2, gamma interferon, and migration inhibitory factors.
  • Lipids from killed tubercle bacillus result in caseous necrosis.
  • Activated macrophages fuse and become multinucleated giant cells.

Educational Objective: Tuberculous granuloma formation is a specialized form of chronic inflammation which is either caused by infections such as Tuberculosis or systemic fungal infections or by non-infectious causes such as Sarcoidosis or Crohn’s disease.
References: Goljan Rapid Review 2nd edition Pg 32]]

Approved Approved::Yes
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