WBR0275

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 36-year-old male presents to the physician’s office complaining of night sweats, chest pain, weight loss, and a 2-month history of coughing that has not responded to cough expectorants. He recently moved back to the United States from West Africa, where he lived in a densely populated city for about 5 years. A physical examination, chest X ray, and Sputum AFB confirm Mycobacterium tuberculosis. Which of the following types of necrosis would you likely find in this condition?]]
Answer A	AnswerA::Caseous necrosis
Answer A Explanation	AnswerAExp::Correct- See explanation
Answer B	AnswerB::Coagulation necrosis
Answer B Explanation	[[AnswerBExp::Incorrect. Coagulation necrosis involves the denaturation of enzymes and structural proteins and microscopically, indistinct outlines of cells are seen within dead tissues even though the structural outline of the dead cells is preserved. This type of necrosis is seen mostly in the heart, liver and kidneys]]
Answer C	AnswerC::Liquefactive necrosis
Answer C Explanation	[[AnswerCExp::Incorrect. Liquefactive necrosis is seen in the brain from the autocatalytic effect of hydrolytic/lysosomal enzymes released by neutrophils or necrotic cells. This is seen in the CNS eg Cerebral infarction or caused primarily by an infection e.g. Abscess in a bacterial infection]]
Answer D	AnswerD::Fat necrosis
Answer D Explanation	AnswerDExp::Incorrect. Fat necrosis is peculiar to fatty tissue eg breast tissue as a result of trauma or adipose tissue seen in an acutely inflamed pancreas
Answer E	AnswerE::Fibrinoid necrosis
Answer E Explanation	AnswerEExp::Incorrect. Fibrinoid necrosis is mostly found in blood vessels such as small arteries, arterioles, venules and glomerular capillaries
Right Answer	RightAnswer::A
Explanation	[[Explanation::Caseous necrosis is a form of necrosis in which caseous material is formed by the release of lipid from the cell walls exhibited by Mycobacterium tuberculosis and systemic fungi such as Histoplasma capsulatum, Coccidioides immitis and Blastomyces dermatitidis. It is associated with acellular, cheese-like material in the center of a granuloma which contains activated macrophages, CD4 helper T cells and multinucleated giant cells. Educational Objective: Caseous necrosis is a type of necrosis formed by the release of lipid from the cell walls of Mycobacterium tuberculosis and systemic fungi with an associated acellular cheese-like material in the center of a granuloma containing macrophages, CD4 helper T cells, and multinucleated giant cells. References: Goljan Rapid Review 2nd edition Pgs 17-18, First AID 2011 Pg 220]]
Approved	Approved::Yes
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